Re: [Repeater-Builder] Digital repeater sidebands??

[Burt Lang]

I just realized that we also have another commercial analog repeater in 
the 420-430MHz band, so close in sidebands would also be a concern.

Burt  VE2BMQ

Burt Lang wrote:
> Hi folks
>
> We have a digital repeater in the 420-430 MHz subband that is being
> installed shortly on our site.  I am concerned about the possible
> interference to systems in the 440-450Mhz subband on the same site.
>
> What experience have you folks had with similar systems and
> installations?  What is the typical sideband levels from commercial
> digital repeaters at 10MHz+ spacing?
>
> FYI this site is owned by our club and we have full control over the
> installations on it including the commercial customers who lease space
> on it.  I just want to know what to look for when this new system is
> installed.
>
> Burt  VE2BMQ
>
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>
>

[Repeater-Builder] Digital repeater sidebands??

[Burt Lang]

Hi folks

We have a digital repeater in the 420-430 MHz subband that is being 
installed shortly on our site.  I am concerned about the possible 
interference to systems in the 440-450Mhz subband on the same site.

What experience have you folks had with similar systems and 
installations?  What is the typical sideband levels from commercial 
digital repeaters at 10MHz+ spacing?

FYI this site is owned by our club and we have full control over the 
installations on it including the commercial customers who lease space 
on it.  I just want to know what to look for when this new system is 
installed.

Burt  VE2BMQ

Re: [Repeater-Builder] Re: Invar Rods

[Burt Lang]

What diameter are the rods?  The older Sinclair VHF Hi cans used 5/16in
diameter whereas the newer cans used 1/4 in daiameter.

burkleoj wrote:
> Glenn, I need 6 of them for a Sinclair duplexer that I have.
>
> Someone cut the rods off when it was originally on a commercial
> frequency. The rods in my duplexer are so short that it will not tune
> below 147 MHz before they disappear inside the top of the cavity.

Very common when the frequencies are in the high 160s

>
> I can get some dimensions for you to see if the ones you have may
> work.
>
> Thanks, Joe - WA7JAW

You can buy invar rod material from some metal suppliers but you won't 
like the price. It normally comes in 12ft lengths but the dealers will 
cut it in half in order to ship UPS. The last time I bought some (around 
1990) the price was $30/lb.  The dealer was Diezel (or Diesel) Metals on 
Long Island somewhere.  I still have some left from that order.

FYI Invar is an allow consisting of exactly 35.16% nickel with the 
remainder iron.  It is magnetic and will corrode in a damp environment 
leaving a green "rust" on the surface.

Burt  VE2BMQ

Re: [Repeater-Builder] Sinclair dipole phasing harness

[Burt Lang]

Hi Paul

Did I hear my name mentioned???  Maybe just ESP:-)

Some time ago the ISP I originally used merged with anther. I had files 
on another ISP (rocler.qc.ca) but dropped it due to a dispute concerning 
SPAM filtering.  All my files that I kept have been moved to my own 
domain website (gorum.ca) where I have better control over it.  The old 
NEDA packet files are on another site that I use.

The folded dipole clone info is at:

http://www.gorum.ca/fdipolev.htm  or download fdipolev.gif from the 
gorum.ca site.  (Sometimes the link gets redirected to sedoparking.com 
which I have trouble getting rid of.)

I would suggest that you don't even consider putting the harnass inside 
the mast (unless Harold can tell us how Sinclair does it).  Put the 
harness on the outside of the mast like the SRL210A4.

You do have it right that there is a matching piece of 125 ohm coax 
(RG-63/U) inside the dipole.  This makes the impedance of each dipole 50 
ohms.

To combine the impedances on a 4 bay Sinclair array is simple.  Divide 
the dipoles into pairs and parallel them.  This gives 25 ohms.  Then add 
an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 
100 ohms.  Combine the matching coax from each pair in parallel to give 
50 ohms.  Then you can connect your feedline at any length from this 
latter 50 ohm connection.

That takes care of the impedance but you first must match the phase of 
the rf signal at each dipole.  Failure to consider the phase matching 
will result in a really messed up vertical pattern (unless you are very 
very lucky).

Matching the phase simply means that the electrical wavelength along 
each feedline path to each dipole has to be as close to equal as 
possible.  They don't have to be any particular wavelength, just so long 
as they are all equal electrically.  Saying this is easy, measuring the 
wavelength is not easy and requires some speciallized test equipment.

I don't know how others measure electrical wavelength, possibly using a 
network analyzer (which I don't have).  What I use is an old HP803A VHF 
RF Bridge fed with a signal generator and a spectrum analyzer as a null 
detector.  The other essential component of this setup is a "Z-Theta 
Chart" which looks sort of like a Smith Chart.  See:

http://www.gorum.ca/z-theta-8x11.gif

On the chart, the resistance and reactance components of the impedance 
are plotted on the inside of the chart and a line drawn between them 
will intersect the relative electrical wavelength around the perimeter.
The wavelength can be measured to better than 0.002.  There is an HP 
application note that explains the process in detail.  I could scan it 
if anyone is interested.

The wavelength on the feedlines of each of the dipoles is measured and 
the shortest one selected.  The other feedlines are then shortened by 
the necessary incremental length to make them all electrically equal. Of 
course this has to be done as a first step before paralleling the feedlines.

That is my experience.  Others may have different ways to achieve the 
same end result.

Burt  VE2BMQ

N1BUG wrote:
> Me again. I just got "handed" a potential project.
>
> I am looking for information on the phasing harness for Sinclair VHF
> 4-bay dipole arrays with the coax inside the mast. I want to know
> types of coax and lengths so I can understand the matching. I could
> use info on both the bidirectional and cardioid versions, but
> especially cardioid. The harness lengths must be different in order
> to cram it inside that mast. Burt? Or anyone can shed some light on
> this? (I was thinking Burt had some info on a web site somewhere,
> but I can't seem to find it)
>
> I am aware of the 125 ohm quarter wave section inside Sinclair
> dipoles, but want to know about the rest of the harness.
>
> I am wanting to attempt the difficult or, maybe, impossible... I am
> trying to figure out if it would be possible to use dipoles from an
> SRL235-2 to rebuild what is believed to be and SRL214, and at the
> same time convert the antenna from bidirectional to cardioid
> pattern. I would be constructing my own harness. I think this might
> be possible, if I can find out how the phasing harness for the
> SRL214/cardioid version was made.
>
> Any info out there?
>
> Paul N1BUG
>
>
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>
>

Re: [Repeater-Builder] Sinclair C-Series cable lengths

[Burt Lang]

The units I have seen appear to have a 1/2 wavelength of cable.  The 
loops are typically 1/8 wavelength equivalent and with 2 loops and the 
cable will equal 3/4 wavelength.  I have also seen some of the old 
(rounded top) Sinclair cans with side connectors joined together with 
only a double female adaptor which would be equal to 1/4 wavelength 
connection.

The cable length is not super critical.

Burt VE2BMQ

n...@no6b.com wrote:
> At 4/19/2010 10:24, you wrote:
>
>
>> I have 2 C-Series bandpass cavities, with individual I.L. set at 1.0 db
>> each. When I couple them together and measure, I get a total I.L. of 2.9
>> db. I should see something like 2.1 or 2.2. I have measured the coupling
>> cable and see<  .1 db, so the cable is good. Anyone have an idea why the
>> loss is so high when coupled?
>
> Did you actually measure the individual loss of each can, or are you just
> going by the indicators on the loops?
>
> Try changing the length of cable between the cans.  I think an electrical
> 1/4 wave multiple (1/4, 3/4, 5/4, etc.) is what you want.
>
> Bob NO6B
>
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>
>

Re: [Repeater-Builder] RG21AU CABLE

[Burt Lang]

The "high resistance wire" is nichrome.

As I recall its attenuation is around 20 dB/100ft at 2m.  I built an 
attenuator using it about 35 years ago.  It handled the maximum power 
rating of the coax as long as the first 10 ft from the input was well 
spread out to prevent build up of heat.

There is a more modern version of this cable with the designation of 
RG-221 or RG-222 (sorry I cannot find my Times cable handbook to verify 
the number).  It's attenuation is approximately the same.

Burt  VE2BMQ

Doug wrote:
> At 09:26 PM 24/03/2010, you wrote:
>> Doug,
>>
>>  From what I have found, RG-21A/U cable is 53 ohm impedance, 0.339" outer
>> diameter, double silver-plated copper braid shields, and a solid center
>> conductor of "high resistance wire."  The dielectric is solid polyethylene,
>> and the jacket is black PVC.  If you have a sample of this wire, please
>> reveal what is printed lengthwise on the jacket.
>>
>> 73, Eric Lemmon WB6FLY
> 
> Hi Eric. Well it has Plastoid Corportation RG-21/AU on the black jacket.
> It is stiff coax. You describe it very well. I sort of remember using
> something like this to reduce the power of an old Prog line unit... Here
> in Canada they didn't allow us to turn the power down, you had to use
> an attenuator.
>
> Thanks Eric
>
> Doug
>
>
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>
>

Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)

[Burt Lang]

The low-band loop from Sinclair (SRL 110) was not nearly as wide band as 
the Hi band (SRL210) and UHF models (SRL310).  The latter were designed 
to be mounted either half wave or quarter wave from the tower or mast. 
In the case of the low band loop a half wave would have put the loop 10 
ft from the mast, which would be structually unsound.  The SRL110 were 
normally mounted about 3 ft or so from the mast which is 1/8 wave.  This 
would result in a lower impedance (<200 ohms loop impedance)  requiring 
93 ohm coax as an internal matching transformer (the SRL210 and 310 
series use 125 ohm matching coax).  It also would be much more sensitive 
to spacing from the mast or tower.

At least that has been my experience with the low band loops.

Burt  VE2BMQ

Chuck Kelsey wrote:
> FYI - Sinclair got the extra bandwidth by stager tuning the antenna element 
> from the 1/4-wave matching transformer that is inside the element. The 
> trade-off was a decrease in return loss (higher VSWR).
> 
> Chuck
> WB2EDV
> 
> 
> 
> 
> - Original Message - 
> From: "skipp025" 
> To: 
> Sent: Sunday, November 15, 2009 10:15 AM
> Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
> 
> 
>> If you're building a Low-Band Loop Antenna from scratch...
>> forget the DB-212 and copy the Sinclair Version. The
>> Sinclair Low-Band loop has a lot wider band-width and it's
>> pretty much the same design... if properly done easier to
>> construct hardware wise.
>>
>> s.
>>
>>
>>> "cruizzer77"  wrote:
>>>
>>>
>>>
>>> Thanks for the info. Somewhere else I read that from the mount to the 
>>> outer edge the length should be 51 inches, this will be about the same as 
>>> 52.5 inches from center to outer edge.
>>>
>>> But to build one from scratch I need more info, radius of the loop, 
>>> diameter of the tube, coupling etc. Of course these can be calculated 
>>> from formulas, but as the DB212 seems to be a particular good design it 
>>> would be interesting to know.
>>>
>>>
>>>
>>>
>>>
>>> --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY"  wrote:
 I converted one about 15 years ago for use on 6 meters.  It measured 
 52.5
 inches from center to outer edge.

 -- Original Message --
 Received: Sat, 14 Nov 2009 10:41:05 AM PST
 From: "cruizzer77" 
 To: Repeater-Builder@yahoogroups.com
 Subject: [Repeater-Builder] DB-212 detailed info wanted

> Does anyone have detailed info about the DB-212 antenna (converted to 
> 6m)
 that make it possible to build one from scratch?
> All the measures and info about the mount and feed point are 
> interesting in
 the first place.
> 73 de Martin HB9TZW
>
>
>
>
>>
>>
>>
>> 
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
> 
> 
> 
> 
> 
> 
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.707 / Virus Database: 270.14.66/2504 - Release Date: 11/15/09 
> 02:50:00
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 

Re: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed

[Burt Lang]

John Sehring wrote:
> 
> 
> The only possible problem with this design is feeding a balanced antenna 
> (the folded dipole) with unbalanced feed.  This will lead to some amount 
> of feedline radiation; yes, it is using coax which is shielded but the 
> unwanted RF current in this situation flows on the _outside_ of the 
> coax, on the shield.
> 
> Yes, this is a commercially successful design, but I've got to wonder...

Don't knock success.  There are thousands of such antennas in operation 
and nobody complains about RF currant on the outside of the coax.

> 
> I think a better way would be to use a half-wave section of 50 coax as a 
> combination 4:1 impedance transformer _and_ balun.  Details in almost 
> any ARRL Antenna Handbook.

But can you weatherproof it for commercial usage?


> 
> The only catch to this approach is that the folded dipole element must 
> be designed to yield 200 ohms rather than the more common 300 ohms 
> impedance, so that the 4:1 transform yields 50 ohms.  Again, older 
> versions of the ARRL Ant. Hdbk have details on doing this; it has to do 
> with the element diameter & element spacing.  However, mounting of the 
> antenna on a tower leg or equiv. may reduce the impedance from 300 ohms 
> enough all by itself.

 From my experience, the folded dipole impedance only starts to drop 
when you get closer than 1/4 wavelength from the mounting mast.  1/4 or 
1/2 wave makes no significant difference on the impedance.  Sinclair's 
110C1 low band antenna is however mounted about 1/8 wave from the 
support and has a different matching coax internally (less than 100ohm I 
think).


> 
> When scaling antennas to other frequencies, pay close attention to the 
> physical scaling.  On 1.2 GHz, RF "things" can get quirky.  Do not cut 
> specific-length lines (e.g. phasing lines) using a ruler & the cable's 
> alleged velocity factor, that can be quite a way off.  I use a noise 
> bridge instead or network analyzer.

The design that I showed on the web page was for 2m and 220.  I tried 
making a UHF array with the same 3/4 in diameter tubing and it was 
really flakey.  I found it easier to work with 3/8in tubing at UHF.

I did think about making 900 or higher dipoles with copper tubing type 
hardline like 0.141 in stuff used for microwave lines.  I could not 
figure out how to change the impedance with the normally available 50 
ohm stuff.  It never got beyond the thinking stage.

Burt  VE2BMQ


> 
> 
> --- On *Thu, 8/27/09, Burt Lang //* wrote:
> 
> 
> From: Burt Lang 
> Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay
> design information needed
> To: Repeater-Builder@yahoogroups.com
> Date: Thursday, August 27, 2009, 7:21 AM
> 
>  
> 
> The technique to match the natural 300 ohm impedance of a folded dipole
> to 50 ohms simply uses matching section of an electrical 1/4 wavelength
> of 125 ohm coax (RG-63B). It is usually installing inside the dipole in
> order to be able to weatherproof the dipole easily at the feedpoint but
> I imagine it could be installed external as well. I have a page with a
> pictorial of the design I used some years ago. I made a number of
> arrays for VHF and 220 MHz using this design some time ago.
> 
> http://www.gorum. ca/sinc_ant. html <http://www.gorum.ca/sinc_ant.html>
> 
> (ignore the links at the bottom - I didn't finish the web page set)
> 
> RG-63B is very hard to find and it is not cheap ($3/ft) but I do have a
> quantity left over from when I was making the dipoles 15-20 years ago.
> 
> Burt VE2BMQ
> 
> wd4nmq_1 wrote:
>  > I am looking at building a 2M four bay antenna, But, I have a
>  > question
>  >
>  > My question is the design and construction of folded dipole antennas
>  > used as individual elements in bay type antennas. In doing research
>  > into their construction I came upon a catch. All design info I found
>  > in books, ARRL Antenna Book, etc, says a two element folded dipole
>  > has a nominal input impedance of 300 ohms. But, all sources, DB
>  > Products, Benelec, etc, I see say the nominal input impedance for
>  > each folded dipole element is 50 ohms, 300. I reference WB2EDV's
>  > article on a 440 antenna he built.
>  >
>  > But, the bottom line is can anybody point me to where I can find the
>  > info on designing each element for 50 ohm impedance?
>  >
>  > Jeff wd4nmq
> 
> 
>

Re: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed

[Burt Lang]

Actually 300 ohms is special.  It is the impedance of a folded dipole 
with equal diameter elements, the end result of bending a single piece 
of tubing into a U.  And the impedance is not affected by the spacing 
between the elements (according to the handbook theory).

Burt  VE2BMQ

John Sehring wrote:
> 
> 
> Yes, it does depend on the antenna, to wit, diameter of the elements & 
> spacing between the elements.  Can be made lower or higher than 300 
> ohms.  There's nothing "sacred" about 300 ohm Z.  It was a match for 300 
> ohm TV twinlead in the older daze.
> 
> --John
> 
> --- On *Thu, 8/27/09, Chuck Kelsey //* wrote:
> 
> 
> From: Chuck Kelsey 
> Subject: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay
> design information needed
> To: Repeater-Builder@yahoogroups.com
> Date: Thursday, August 27, 2009, 6:51 AM
> 
>  
> 
> Depends on the antenna.
> 
>   A folded dipole, out in the open, with no matching, is a
> bit less than 300-ohms.
> 
>  
> Chuck
> WB2EDV
>  
> 
> 
> start: -00-00 end: -00-00
> 
> 

Re: [Repeater-Builder] 2 meter folded dipoles for multi bay design information needed

[Burt Lang]

The technique to match the natural 300 ohm impedance of a folded dipole 
to 50 ohms simply uses matching section of an electrical 1/4 wavelength 
of 125 ohm coax (RG-63B).  It is usually installing inside the dipole in 
order to be able to weatherproof the dipole easily at the feedpoint but 
I imagine it could be installed external as well.  I have a page with a 
pictorial of the design I used some years ago.  I made a number of 
arrays for VHF and 220 MHz using this design some time ago.

http://www.gorum.ca/sinc_ant.html

(ignore the links at the bottom - I didn't finish the web page set)

RG-63B is very hard to find and it is not cheap ($3/ft) but I do have a 
quantity left over from when I was making the dipoles 15-20 years ago.

Burt  VE2BMQ


wd4nmq_1 wrote:
> I am looking at building a 2M four bay antenna, But, I have a
> question
> 
> My question is the design and construction of folded dipole antennas
> used as individual elements in bay type antennas. In doing research
> into their construction I came upon a catch. All design info I found
> in books, ARRL Antenna Book, etc, says a two element folded dipole
> has a nominal input impedance of 300 ohms. But, all sources, DB
> Products, Benelec, etc, I see say the nominal input impedance for
> each folded dipole element is 50 ohms, 300. I reference WB2EDV's
> article on a 440 antenna he built.
> 
> But, the bottom line is can anybody point me to where I can find the
> info on designing each element for 50 ohm impedance?
> 
> Jeff wd4nmq

Re: [Repeater-Builder] Sinclair Q202 duplexes (frankenstien series)

[Burt Lang]

Some thoughts from past experience.

Sinclair Q202 cans are not high pass OR low pass, they are both.  They 
have 2 notches, one on either side of the pass, separated by typically 
10 MHz more or less.  The 2 notches move as a pair by varying the series 
capacitance on the loop.  The more capacity the lower they are.  A low 
capacity places the lower of the two notches close to the low side of 
the pass and gives you a high-pass can.  Higher capacity lowers the 
notches until the higher notch is close to the high side of the pass and 
yields a low-pass can.

The value of the capacitance you need for a VHF Hi-band is 1-30 pF, 
adjusted typically to less than 10 pF for a high-pass config and 20-30 
pF for a low-pass config.

One more very important consideration.  The Q of the loop series 
capacitance must be very high (1000+) to get a good deep notch.  Most 
capacitors do not qualify.  The Johanson variable caps (5600 series) 
used in the VHF Q202 cans have a Q of 800+ (at 250MHz), higher at 
150MHz.  The UHF cans use Johanson  1-10pf variable caps (5200 series) 
with a Q or 5000+ (at 250 MHz). If you think about parallelling the 
variable with a fixed cap, the only fixed caps I know of with sufficient 
Q are silver mica units.  The bare uninsulated UNELCO brand transmitting 
caps work well. Other brands may also work but ceramic capacitors 
definitely do not have enough Q for this application.  The other 
alternative I have used at times on VHF cans is to parallel 3 1-10 pF 
Johanson variables.  One advantage of this is that 1-10pf Johanson 
trimmers are common in surplus for 50c-1$ whereas 1-30pf caps are very 
rare in surplus and new cost is upwards of $15 (my Scottish ancestry is 
showing:-)

Good luck in your experiments.

Burt  VE2BMQ



NORM KNAPP wrote:
> Ok, it is official. I have a set of sinclair Q202 duplexers that didn't come 
> as a set. At least two of the cans have different serial numbers and 
> different factory tuned frequncies. DRAT! Ok, so here is the problem. With my 
> trusty Aeroflex 2945 (I think that is the model) I can easily get a -35db 
> notch on each of the hi pass cans at 147.825 pass and 147.225 notch. No 
> problem with that side. Ok, the problem is on the low pass pair (mix-mached I 
> am sure). I can barely get a -30db notch on each can even if I spin the 
> loops. So, just out of (morbid) curiocity, I pulled the loop out of one just 
> to show a fellow ham what was in there. Lo and behold there was a 12pf cap 
> soldered accoss the notch tune cap. H... What would happen if I took this 
> cap off there since to get the -30db notch the tuning cap is almost screwed 
> all the way out (min capacitance). So I got out the soldering iron and 
> removed it. It worked, sort of. I was able to get a -35db notch on my lo pass 
> (147.225 pas
s 147.825 notch) side, but at the expense of some pass loss higher than the 
high pass side. What happend is it seemed to make the low pass can into a high 
pass can. The notch went to the other side of the pass. I spun the loop to get 
the best result and tuned the notch cap near its max capacitance to get the 
notch wher it should be. It worked barely and with a bit more loss in the pass. 
I am thinkin I may need to go back and put a 6pf cap accross the notch tune to 
get it where I want it, but I am not sure. On the second can of the lo pass 
high notch side I tried to remove the cap, but it didn't turn out the same. The 
loop inside it was not silver plated like the previous can, it was just plain 
copper and appeared to be a bit longer. When I removed the cap on this can, the 
notch went to the low side of the pass and I couldn't get it to come back 
around. I will definitly have to try a 6pf cap accross the notch tune cap on 
this one.
> Now, I just replaced the harness with RG-214/U jumpers the length needed to 
> get 14" between centers of the "Tee's". The old ones were RG-142/U and were 
> also apparently the correct lenght as well. Changing the jumpers didn't seem 
> to affect the tuning ability of the cans. It was a waisted effort really, but 
> oh well, they have a really nice new harness on them, makes em look 10 years 
> newer.
> Any suggestions guys. It lookes like I may have a modified pair of cans that 
> are actually high pass instead of low pass. Should I play with the lenght of 
> the loop? What about changing the 12pf caps accross the notch tune caps 
> (parralell) to 6pf or so? Right now, they are working, but the high pass pair 
> look really good and the low pass pair look so-so to kinda oK. The repeater 
> is working very well, but I feel if I get the cans right it will be even 
> better.
> Anu suggestions?
> Call me if you like 251-234-0295.
> 73 de N5NPO
> Norm
> 
>

Re: [Repeater-Builder] Re: DC Ground Lightning Protection / Concrete Electrode

[Burt Lang]

I would suggest anyone interested in this subject should Google "Ufer 
ground" and get the real facts on the subject.  The key to the "concrete 
encased ground electrode" is a properly installed rebar reinforcing in 
the concrete base.

Burt  VE2BMQ

Ed Bathgate wrote:
> 
> 
> 
> I'm going to disagree with the following posting:
> 
> If the tower is bolted to galvanized pipe that is embedded in concrete of
> which a significant amount is in contact with soil, you have a
> "concrete-encased grounding electrode" which is hard to improve upon. It is
> not likely that a ground rod would be worthwhile, since damp concrete
> (concrete in intimate contact with soil at grade level) is a fairly good
> conductor, and such a footing or foundation has hundreds of times the
> surface area of a ground rod.
> 
> I have read Ericsson specs for cellular tower installation in that 
> disagrees with the previous statement.
> 
> Standard concrete without conductive enhancing materials can crack, pop 
> or crumble if subjected to a direct lightning strike if ground rods are 
> not properly installed.   The water contained within the concrete will 
> vaporize instantly causing the concrete to fail.
> 
> There are types of conductive concrete mixes or additives that can be 
> used, but the most common practice is to use a ground rod from each leg 
> with a copper wire bonded to each tower leg.
> 
> Our mfg building at work is made from steel I-Beams into concrete.  I 
> have noticed each I-Beam has its own ground connection.  The strap is 
> bolted to the beam about 1" above the concrete, then disappears into the 
> concrete, and suspect there is a ground rod going into the soil beneath 
> the concrete piling, but that’s just a theory, as I dident see it before 
> the mud was poured.
> 
> Ed N3SDO
> 
> 
> 
> 






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Re: [Repeater-Builder] Re: OT: Value of IC-22A and IC-22U

[Burt Lang]

Keep in mind that the 22S and possible the other variations had a 
problem of intermittant solder joints on the steel pins that were used 
as feedthrus on the circuit boards.

Burt Lang

Greg Beat wrote:
> 
> 
> The Icom IC-22A is crystal-controlled, so has ultimate flexibility (at 
> the price of crystals).
> The Icom IC-22U came after the IC-22S (23 channel with diode matrix 
> board) --
> I had the 22S one in late 1970s (popular unit at the time).
>  
> Generally, I have seen them sell on eBay for ~ $15 to $50 largely based 
> upon condition (if included box, manual, microphone, cosmetic condition, 
> etc.).  Neither unit had CTCSS as a standard option (add-in board, 
> like ComSpec SS-64, required).
>  
> w9gb
> 
> 
> 






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Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)

[Burt Lang]

Paul Kelley N1BUG wrote:
> Hi Burt,

snip

>> You could try using 3/4 wavelength matching pieces to get the extra 
>> length.  That should be equivalent to 1/4 wave but will be more 
>> sensitive to frequency changes.
> 
> I only need to extend them by about a foot to get ideal spacing 
> between dipoles, so 1/4 wavelength with .66 VF would be enough.

Be careful how you splice.  I normally used short pieces of thin wall 
brass tubing of appropriate size to splice the center conductor.  You 
can get this tubing in various sizes (increments of 1/32in diameter up 
to 9/16 OD) (K&S brand) at most hobby shops.  You can also use a piece 
of larger tubing to splice the shields.  The most important step is the 
use of heavy adhesive lined shrink tubing to seal and waterproof the joint.

> 
>> Never having seen one of those antennas (the SD2352) up close, I am not 
>> sure of the harness configuration and how it would compare to the SD214 
>> that I am familiar with.
> 
> Total of 8 dipoles. Impedance at end of coax coming from each dipole 
> approximately 50 ohms. Two dipoles connect to a type N tee, so at 
> the tee center should be about 25 ohms. From there, 1/4 wavelength 
> RG-213 to a a factory harness 'Y' splice, coax should transform the 
> impedance to about 100 ohms, divided by 2 at the Y so we're back to 
> 50 ohms coming out of there. From there, approximately 66 inches 
> RG-213 to the center Y splice of the overall harness. This coax 
> should maintain 50 ohms, divided by two at the center Y splice = 25 
> ohms. There is a 1/4 wavelength of some coax coming out of there, 
> spliced to a length of RG213 running down to the bottom of the mast. 
> I'm assuming the 1/4 wavelength matching section is 35 ohm coax, but 
> cannot confirm that. This description may be "clear as mud"... I can 
> make a diagram of it later if you want.

That is exactly what I would have expected ie same as the SRL210 series. 
  BTW the Wireman may have RG-83 35 ohm coax available - at least he had 
many years ago when I inquired.  When I got my stock of RG-63B I had to 
buy a 500 ft roll at many , which was only practical since I 
intended to make many antennas.  I probably only used 175 ft of the 
roll.  The high cost is due to the fact that the cable was true Mil-Spec 
(complete with compliance records) and small demand/production runs. 
The same would apply to RG-83.

> 
>> Figuring out the failure mode is the most important first step.  Then 
>> you can go from there to possible solutions whether it is harness 
>> replacement, repair or dig into the dipoles.
> 
> I have decided no matter what I'm not putting it back up as an 8 
> dipole bidirectional array so I will take apart the original harness 
> for inspection. I will also test each of the dipoles on the repeater 
> individually to check for noise. If I do not find any problems in 
> either of these processes, then I will have no clue what caused the 
> problem!

Consider the possibility that water has got into the RG-213 and corroded 
the shield.  This would likely give noise when RF is applied but not be 
particularly sensitive to vibration.  Look for green copper shields, it 
is not environmentally friendly :-)

Burt>>

> 
> Paul N1BUG
> 
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 

Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)

[Burt Lang]

Hi Paul

The info I gave you applied to the SD214 series antennas (old SRL210A4 
oe 210C4).  I am guessing that it would also apply to the cheaper SD2352 
series.

Let's hope you don't need to get inside the dipole itself.  BTW what is 
the diameter of the aluminum tubing used on the SD2352?  The SD214 uses 
3/4in OD.

Paul Kelley N1BUG wrote:
> Thanks Burt!
> 
> If all the dipoles seem to be OK (not noisy) I am thinking of making 
> my own harness to use 4 of them. I've constructed several 
> multiple-antenna EME arrays so I understand the concepts and the 
> importance of equal lengths, etc.

I used an old HP RF impedance bridge to match the harness sections on 
the antennas I built.  It allowed me to match actual electrical lengths 
to within .01 wavelength.

> 
> My only concern with making my own harness is that the length of 
> coax attached to each dipole is not long enough to reach a tee 
> connector on the mast and allow sufficient vertical spacing between 
> dipoles. (The original configuration had four bays of two side by 
> side dipoles, so the shorter length was appropriate there.) It will 
> be easy enough to add on some coax but since the impedance at my 147 
> MHz frequency is not exactly 50 ohms and somewhat reactive it will 
> vary somewhat with the coax length. I don't think it will be enough 
> to cause major issues.

You could try using 3/4 wavelength matching pieces to get the extra 
length.  That should be equivalent to 1/4 wave but will be more 
sensitive to frequency changes.

> 
> I see that I will need to use some odd multiple of a quarter 
> wavelength for the 50 ohm coax sections from the array center tee to 
> each of the outer tees feeding pairs of dipoles.

Never having seen one of those antennas (the SD2352) up close, I am not 
sure of the harness configuration and how it would compare to the SD214 
that I am familiar with.

> 
> I need to see if I can figure out what failed and why in the 
> original configuration before I go investing time and money into a 
> rebuild though. Its useful service life before becoming too noisy 
> was less than a year!

Figuring out the failure mode is the most important first step.  Then 
you can go from there to possible solutions whether it is harness 
replacement, repair or dig into the dipoles.

Good luck

Burt>>>
> 
> Paul N1BUG
> 
> 

Re: [Repeater-Builder] Sinclair dipole array premature failure (noisy)

[Burt Lang]

The matching section inside the loop is a 1/4 wavelength of RG-63B 125 
ohm coax.  The overall outside diameter is the same as RG-214 but the 
dielectric is semi-air (like a large version of RG-62 93 ohm coax) and 
the center conductor is quite small, like RG-59.  I have a few hundred 
feet of RG-63B if you want to experiment.

The actual length of the matching section in the commercial loop is not 
however a 1/4 wavelength at the center freq of the dipole but rather on 
the high side.  A Sinclair loop I dismantled had a matching section that 
was 1/4 wave at 182 MHz.  I believe that this is the secret to the extra 
wide bandwidth of the dipole.  Using a matching section that is 1/4 wave 
at the center freq of the dipole (156 MHz) gives a much better return 
loss at 156 MHz but is at least 20% narrower bandwidth.

I have made a number of clones with both the dipole and the matching 
section tuned to 146MHz.  The return loss was very good at 2m (SWR very 
close to 1:1 vs the commercial antenna that was 1.2:1 at its lowest 
point over the 138-174 MHz bandwidth.)  I also used the same design in 
several 4 bay 220MHz versions that have been in service for up to 15 years.

Check the following URL for a diagram of my clone design:

http://www.gorum.ca/fdipolev.gif

One point of warning:  It is very hard to insert the coax into the loop. 
  You have to make as short a splice as possible since it must slide 
past the 180 deg bend in the loop.  Avoid messing with this coax unless 
absolutely necessary.

As for the harness, the key point is that the electrical length of the 
RG-213 from each dipole must be identical.  The actual electrical length 
is unimportant, it just has to be the same for all dipoles.  The actual 
configuration of the harness depends on the number of dipoles.  One and 
4 dipoles can be made entirely with RG-213 whereas 2 and 8 dipoles 
require a 1/4 wave section of RG-83 35 ohm coax. The one mystery I have 
is how Sinclair inserts the harness into the mast for the fully enclosed 
model.  The matching section parts of the harness are completely inside 
the mast and is beyond the means of us amateurs.  However an external 
harness is very practical.

Burt Lang  VE2BMQ

Paul Kelley N1BUG wrote:
> That's what I thought Chuck. Thanks! I haven't yet decided whether I 
> want to rip the heat shrink tubing off an element and disassemble it 
> to see what coax is inside, which is why I asked.
> 
> I was sort of contemplating whether it might be possible to replace 
> all that coax with RG-214 in an attempt to build a noise free 
> harness. But if there's a matching section, I'm sure the return loss 
> without it would be really ugly.
> 
> Paul N1BUG
> 
> 
> Chuck Kelsey wrote:
>> There is a 1/4 wave impedance matching section of coax (125?) inside the 
>> element. The matching section is stagger tuned from the element itself. 
>> That's why it is more boadbanded and why you see two return loss dips.
>>
>> Chuck
>> WB2EDV
>>
>>
>> - Original Message - >
>>
>>> I wonder if anyone knows what (if any) gimmick Sinclair used to get
>>> such broad SWR bandwidth on these dipoles? The exposed portion of
>>> the coax on each dipole is RG-213, 50 ohms... but I'm wondering if
>>> they may use some quarter wavelength (or ???) of some other
>>> impedance on the part hidden inside the dipole, especially since
>>> these things exhibit a clear double dip SWR curve (one dip near the
>>> low end of the design range, 138 MHz, and another dip near the upper
>>> end, 174 MHz, with a somewhat reactive bump in between).
>>>
>>> 73,
>>> Paul N1BUG
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 

Re: [Repeater-Builder] Re: Need supplier for UHF welded yagi

[Burt Lang]

Comprod's main plant is located in Boucherville QC on the Montreal south 
shore.  Like Sinclair, they appear to have a american branch plant to 
supply the "Made in America" demand that was opened in 2005.  It is 
located near Buffalo in Orchard Park, NY.

Burt VE2BMQ


Gran Clark wrote:
> Lee
> 
> Thanks for your input!  I did call them and it looks like a good shot.  
> Their amateur price was in the ball park.  It sounds like a small 
> company in New York.
> 
> Gran
> 
> At 09:57 PM 3/29/2009, you wrote:
> 
>> Sinclair makes decent antennas, but if you really want something to 
>> survive in a harsh environment, check out Comprod Communications.
>>
>> http://www.comprodcom.com/en/antennas/base/pdf/480-70.pdf
>>
>> They make antennas that survive nearly anything. Out here on the West 
>> Coast we routinely get lots of hard rime ice on coastal mountaintop 
>> sites, combined with 100mph+ sustained winds.
>>
>> Sinclair antennas get elements snapped off all the time (inherent 
>> design flaws, even on their HD antennas). The Comprod antennas keep on 
>> going.
>>
>> Regardless, stay away from Bluewave... they may look like a good 
>> antenna (and physically they are strong), but some of their models 
>> have water ingress problems which lead to antenna failure.
>>
>> Lee
>>
>> --- In Repeater-Builder@yahoogroups.com 
>> , Gran Clark  wrote:
>> >
>> > Chuck
>> >
>> > I will call Sinclair. They don't list a welded antenna. On the
>> > beam I have the elements are mounted on the outside of the boom
>> > which I would think would be hard to make a good weld if I went that 
>> way.
>> >
>> > Gran
>> >
>> >
>>
> 
> 
> 

[Repeater-Builder] Re: simplex repeater

[Burt Lang]

Somewhere in my pile of data books I have an application note that 
refers to a "simplex repeater" being used in commercial applications. 
The booklet was from either dB Products or Pye as I recall.  The purpose 
of their "simplex repeater" was to fill local coverage holes.  The 
equipment described consisted of 2 beam antennas, one pointed at the 
source and the other pointed at the hole  with an amplifier and filter 
between them.  The antennas were adjusted for maximum isolation and the 
amplifier gain was set to be considerably less than the isolation 
between the antennas.

Similar setups were used in the early days of television to give 
coverage in behind mountains.

These setups would simultaneously transmit on the same frequency.

Has anyone else seen such application notes or booklets???

Burt  VE2BMQ

MCH wrote:
> Just because you call something a repeater doesn't mean it is.
> 
> A "simplex repeater" is not a repeater due to two things: 1. It does not 
> simultaneously retransmit, and 2. It transmits on the same frequency. 
> Point #1 was just clarified by the FCC Monday, but point #2 has never 
> been misinterpreted in the FCC definition, AFAIK.
> 
> Joe M.
> 
> Dave Gomberg wrote:
>> At 16:34 3/24/2009, Jeff Condit wrote:
>>> What do you call it when messages are recorded and then 
>>> retransmission begins right after reception ends?  By this 
>>> definition it would not constitute a "simplex repeater", right?
>> That is exactly m y understanding of what "simplex repeater" means
>>
>>> Jeff Condit
>>
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 

Re: [Repeater-Builder] exec I vs exec II

[Burt Lang]

The MASTR Exec (1) came in two flavors (at least here in Canada), the 
Exec with a tube final and the Royal Exec with a solid state final.  The 
receivers in both cases was very similar.  The receivers are very 
sensitive and also quite tough.  I saw one where the input trace on the 
circuit board had evaporated  due to an arc (from induced lightning) to 
the case 1/8 inch away.  Jumpered the trace and the RX sensitivity came 
back to normal.

BTW the Exec receiver makes a very good 220 receiver.  The majority of 
220 repeaters here in the Montreal area use them.

Burt  VE2BMQ

John J. Riddell wrote:
> Correct.The exec 1 had totally different innardsthe exec II is 
> similar to the Mastr II
> 
> The exec 1 had three tubes8106, x 2and 7984 PA
> 
> John VE3AMZ
> 
> 
> - Original Message - 
> From: "Thomas Oliver" 
> To: 
> Sent: Tuesday, March 03, 2009 5:29 PM
> Subject: RE: [Repeater-Builder] exec I vs exec II
> 
> 
>> I think the exec I had a tube final RX was solid state looks nothing like
>> an exec II so I would say no.
>>
>> tom
>>
>>
>>> [Original Message]
>>> From: Chris Curtis 
>>> To: 
>>> Date: 3/3/2009 5:06:57 PM
>>> Subject: [Repeater-Builder] exec I vs exec II
>>>
>>> Anyone have a "short version" of the differences between an exec I 
>>> station
>>> and an exec II station?
>>> Are the innards swappable?
>>>
>>> Thanks for your time.
>>>
>>> Chris
>>> Kb0wlf
>>>
>>>
>>>
>>> 
>>>
>>>
>>>
>>> Yahoo! Groups Links
>>>
>>>
>>>
>>
>>
>> 
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 

Re: [Repeater-Builder] Six Meter Repeater Noise Issues

[Burt Lang]

I have found a simple way to verify if noise is coming from a power line 
arc-over.  Any such noise generated by a power line will only occur as 
the voltage on the line approaches peak and it will be synchronized to 
120 Hz.  Put an oscilloscope on the audio while feeding an unmodulated 
carrier into the receiver and set the time base trigger to 60Hz.  If the 
noise is pulsing and stays solid on the scope display, you have power 
line noise.  If it is steady (not pulsed) and not synchronized to 120 
Hz, the power line is not the culprit.

Burt  VE2BMQ


Chuck Kelsey wrote:
> If it's power line noise you can check by keeping your TX off and have 
> someone with a noisy signal key up on the repeater input while you 
> listen on the local receiver. You could use your signal generator into a 
> whip antenna. You'll know if there's something in there. You won't hear 
> it without an incoming signal, by the way.
>  
> Chuck
> WB2EDV
>  
>  
>  
> 
> - Original Message -
> *From:* Scott 
> *To:* Repeater-Builder@yahoogroups.com
> 
> *Cc:* Scott Overstreet 
> *Sent:* Thursday, December 25, 2008 12:18 PM
> *Subject:* Re: [Repeater-Builder] Six Meter Repeater Noise Issues
> 
> Tom
>  
> I think you have a corrosion problem in your antenna system.
>  
> I had a similar if not identical problem in a 2 meter repeater
> hereyears of good performance and then serious desense. I ran
> the same tests as you have with same results.
>  
> The fix here was an overhaul of the Hustler 144-G7 if I remember the
> numbers right. Corrosion was found in several places-fix was to
> clean down to bare metal to bare metal and reassemble with no-ox in
> the joint and more under several layers of shrink tubing over the
> top for weather protection. The antenna is still in service with no
> trouble.
>  
> Corrosion in the antenna results in transmitter signal rectification
> within the antenna which produces noise of sufficient bandwidth to
> cover your receive frequency and this of course comes back down your
> feedline and properly goes right through your duplexer into your
> receiver. The curious thing is that under most conditions, this wide
> band noise results in desense without changing the audio noise
> output from your repeater receiver when your repeater transmitter is
> switched off.
>  
> The fact that desense goes away when the antenna is replaced with a
> dummy---I assume that you are injecting your test signal into you
> receiver using an attenuating "T"I think your problem is your
> antenna or something very close by that it is exciting.
>  
> Scott
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
> 
> - Original Message -
> *From:* Tom Elmore 
> *To:* Repeater-Builder@yahoogroups.com
> 
> *Sent:* Tuesday, December 23, 2008 10:03 AM
> *Subject:* [Repeater-Builder] Six Meter Repeater Noise Issues
> 
> Several months ago I put a six meter machine on the air in
> my area. It  is a GE Master Pro tuned for 52.810 out and
> 51.110 in.  One of the things still nagging me is some sort
> of desense or RF phase noise, let me explain.  After tuning
> up the duplexers into a dummy load and running some tests I
> experienced no desense all the way down to about .15uV.  I
> moved  the dummy load to the end of the transmission line
> just to be sure and again the same results. When I put the
> antenna in line and run the same tests this is what occurs.
> When I key the transmitter and set the output of the signal
> generator from a starting point of say 100 uV I hear what
> sounds like phase noise or just plain static just slightly
> in the background. As I bring the signal generator output
> down the background noise gets louder but it never wipes out
> or overloads the receiver altogether as I can still hear the
> generator and the background noise and this is down to the
> same squelch threshold I get when on the dummy load. I am
> hesitant to call this desense as say when one of the
> duplexer cavities isn't tuned correctly. Then it is obvious
> because the transmitter totally wipes out the signal I am
> feeding it from the signal generator. I thought perhaps the
> preamp was the culprit so I took it out of line but sill
> experience the same issue. I am thinking that possibly the
> repeater output from the antenna is getting ba

Re: [Repeater-Builder] Re: fan timer circuit

[Burt Lang]

One more thing to be careful of when using fans on remote equipment. 
Make sure there are guards on both sides of the fan.  We had a muffin 
fan on a 100wt 220 amp that failed when a mouse tried to get closer to 
the warm heatsink.  His carcass jammed the fan blades and got dessicated 
with the heat.

Burt Lang  VE2BMQ

Re: [Repeater-Builder] Modification on old Q202

[Burt Lang]

30pF Johanson trimmer #5602

Burt VE2BMQ

Eric wrote:
> Hi group,
>
> I have an old duplexer Q202 without harness and I want to transform the 
> pass cavite into Q Filter, with a piston capacitor in serial with the 
> loop.
>
> Maybe someone in the group know the range in pF of this capacitor for 
> VHF ham band?
>
> My freq. are TX 147.165 and RX 147.165
>
> Thank you for your help.
> Eric
>
>
> 
>
>
>
> Yahoo! Groups Links
>
>
>
>
>   

Re: [Repeater-Builder] Re: antenna question - Dip It and Scotch Kote

[Burt Lang]

Sorry Joe, I misunderstood the original procedure.  I can see the 
purpose of the water now although I still don't believe that an empty 
oven will burn out easily.  If that was true, most of the ovens in the 
country would now be dead because most everyone is guilty of turning on 
one with little or nothing in it.

Burt>>>

MCH wrote:
> You don't care if the cup of water heats up - you are looking to see if 
> the painted cup heats up. The water is only there to prevent burning out 
> the microwave.
> 
> Joe M.
> 
> Burt Lang wrote:
>> Fine except for one problem.  Water is an excellant absorber of the 
>> microwaves used in the microwave ovens (2.45 GHz)  So your water will 
>> heat up quickly irregardless of the coating.  The only substances that 
>> are better absorbers of that frequency are animal or vegetable fats 
>> because they contain 9 times the molecular bonds (the O-H bond) that 
>> actually do the absorbing.
>>
>> Burt  VE2BMQ  (who used to be a professional chemist)
>>
>> IM Ashford wrote:
>>> Paint a polythene cup with your favourite antenna covering. Let it dry 
>>> and put it into the microwave oven along  with a cup of water (to act as 
>>> a dummy load)
>>> Cook for 1 min on max power.
>>> If it gets even slightly warm its no good for antennas.
>>>  
>>> er.. can I please have an award for the first cooking recipe to get past 
>>> the moderator on repeater-builder
>>>  
>>> Ian
>>> G8PWE
>>>  
>>>
>>> - Original Message -
>>> *From:* skipp025 <mailto:[EMAIL PROTECTED]>
>>> *To:* Repeater-Builder@yahoogroups.com
>>> <mailto:Repeater-Builder@yahoogroups.com>
>>> *Sent:* Sunday, May 04, 2008 2:44 PM
>>> *Subject:* [Repeater-Builder] Re: antenna question - Dip It and
>>> Scotch Kote
>>>
>>> I constructed a 6 meter beam some years back, worked like a bomb
>>> even at 25ft above ground elevation. To ensure my pride and joy
>>> would last a long time I sprayed it with clear Krylon brand spray
>>> paint.
>>>
>>> The antenna was instantly unusable regardless of my efforts to
>>> remove the paint, re-tune or otherwise modify the antenna. I later
>>> learned that type of paint contained materials with a horible
>>> D-Factor. I was never able to use the antenna again, although it
>>> remains in my back yard as a reminder.
>>>
>>> cheers,
>>> s.
>>>
>>>  > "Chuck Kelsey" <[EMAIL PROTECTED]> wrote:
>>>  > Boy, you took a gamble. I'd have been afraid that this action
>>>  > could have either messed up the VSWR or shifted the resonant
>>>  > point of the antenna. Then again, maybe it did and either
>>>  > you don't know that or it wasn't significant.
>>>  >
>>>  > Chuck
>>>  > WB2EDV
>>>  >
>>>  >
>>>  > - Original Message -
>>>  > From: "skipp025" <[EMAIL PROTECTED]>
>>>  > To: >> <mailto:Repeater-Builder%40yahoogroups.com>>
>>>  > Sent: Sunday, May 04, 2008 12:19 AM
>>>  > Subject: [Repeater-Builder] Re: antenna question - Dip It and Scotch
>>> Kote
>>>  >
>>>  >
>>>  > > Hi Robert,
>>>  > >
>>>  > > You might get lucky... because they might also have advertised
>>>  > > the dip-it as an insulator material, which means someone was
>>>  > > hopefully looking at the dissipation factor (aka D-Factor) when
>>>  > > the compound was engineered. Time will tell...
>>>  > >
>>>  > > cheers,
>>>  > > skipp
>>>  > >
>>>  > >> "georgiaskywarn"  wrote:
>>>  > >> Someone else told me that after I had put a whole can of dip
>>>  > >> it on the db408 I showed you. I went back and covered every
>>>  > >> inch of it with liquid electrical tape. I have had good
>>>  > >> results in the GA sun with it.
>>>  > >> 73,
>>>  > >> Robert
>>>  > >> KD4YDC
>>>  > >>
>>>  >
>>>
>>>
>> 
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Re: antenna question - Dip It and Scotch Kote

[Burt Lang]

Think about it.  If you expect the water to act as a heatsink, it would 
require the cup to transfer heat thru its material.  Heat can go both 
ways and you will never know if heat generated on the outside is heating 
the water or vice versa, the water is passing thru the cup to the 
outside.  Put a coffee cup of water into your microwave and see how hot 
the outside of the cup gets when the water is heated.

Even if you use a foam cup to isolate the outside from the inside and 
are using the water to provide a load on the magnatron (which it doesn't 
need), there will be enough moisture in the foam for it to heat up and 
probably melt leaving a real mess to cleanup.

Burt>>>

MCH wrote:
> You don't care if the cup of water heats up - you are looking to see if 
> the painted cup heats up. The water is only there to prevent burning out 
> the microwave.
> 
> Joe M.
> 
> Burt Lang wrote:
>> Fine except for one problem.  Water is an excellant absorber of the 
>> microwaves used in the microwave ovens (2.45 GHz)  So your water will 
>> heat up quickly irregardless of the coating.  The only substances that 
>> are better absorbers of that frequency are animal or vegetable fats 
>> because they contain 9 times the molecular bonds (the O-H bond) that 
>> actually do the absorbing.
>>
>> Burt  VE2BMQ  (who used to be a professional chemist)
>>
>> IM Ashford wrote:
>>> Paint a polythene cup with your favourite antenna covering. Let it dry 
>>> and put it into the microwave oven along  with a cup of water (to act as 
>>> a dummy load)
>>> Cook for 1 min on max power.
>>> If it gets even slightly warm its no good for antennas.
>>>  
>>> er.. can I please have an award for the first cooking recipe to get past 
>>> the moderator on repeater-builder
>>>  
>>> Ian
>>> G8PWE
>>>  
>>>
>>> - Original Message -
>>> *From:* skipp025 <mailto:[EMAIL PROTECTED]>
>>> *To:* Repeater-Builder@yahoogroups.com
>>> <mailto:Repeater-Builder@yahoogroups.com>
>>> *Sent:* Sunday, May 04, 2008 2:44 PM
>>> *Subject:* [Repeater-Builder] Re: antenna question - Dip It and
>>> Scotch Kote
>>>
>>> I constructed a 6 meter beam some years back, worked like a bomb
>>> even at 25ft above ground elevation. To ensure my pride and joy
>>> would last a long time I sprayed it with clear Krylon brand spray
>>> paint.
>>>
>>> The antenna was instantly unusable regardless of my efforts to
>>> remove the paint, re-tune or otherwise modify the antenna. I later
>>> learned that type of paint contained materials with a horible
>>> D-Factor. I was never able to use the antenna again, although it
>>> remains in my back yard as a reminder.
>>>
>>> cheers,
>>> s.
>>>
>>>  > "Chuck Kelsey" <[EMAIL PROTECTED]> wrote:
>>>  > Boy, you took a gamble. I'd have been afraid that this action
>>>  > could have either messed up the VSWR or shifted the resonant
>>>  > point of the antenna. Then again, maybe it did and either
>>>  > you don't know that or it wasn't significant.
>>>  >
>>>  > Chuck
>>>  > WB2EDV
>>>  >
>>>  >
>>>  > - Original Message -
>>>  > From: "skipp025" <[EMAIL PROTECTED]>
>>>  > To: >> <mailto:Repeater-Builder%40yahoogroups.com>>
>>>  > Sent: Sunday, May 04, 2008 12:19 AM
>>>  > Subject: [Repeater-Builder] Re: antenna question - Dip It and Scotch
>>> Kote
>>>  >
>>>  >
>>>  > > Hi Robert,
>>>  > >
>>>  > > You might get lucky... because they might also have advertised
>>>  > > the dip-it as an insulator material, which means someone was
>>>  > > hopefully looking at the dissipation factor (aka D-Factor) when
>>>  > > the compound was engineered. Time will tell...
>>>  > >
>>>  > > cheers,
>>>  > > skipp
>>>  > >
>>>  > >> "georgiaskywarn"  wrote:
>>>  > >> Someone else told me that after I had put a whole can of dip
>>>  > >> it on the db408 I showed you. I went back and covered every
>>>  > >> inch of it with liquid electrical tape. I have had good
>>>  > >> results in the GA sun with it.
>>>  > >> 73,
>>>  > >> Robert
>>>  > >> KD4YDC
>>>  > >>
>>>  >
>>>
>>>
>> 
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Re: antenna question - Dip It and Scotch Kote

[Burt Lang]

Fine except for one problem.  Water is an excellant absorber of the 
microwaves used in the microwave ovens (2.45 GHz)  So your water will 
heat up quickly irregardless of the coating.  The only substances that 
are better absorbers of that frequency are animal or vegetable fats 
because they contain 9 times the molecular bonds (the O-H bond) that 
actually do the absorbing.

Burt  VE2BMQ  (who used to be a professional chemist)

IM Ashford wrote:
> Paint a polythene cup with your favourite antenna covering. Let it dry 
> and put it into the microwave oven along  with a cup of water (to act as 
> a dummy load)
> Cook for 1 min on max power.
> If it gets even slightly warm its no good for antennas.
>  
> er.. can I please have an award for the first cooking recipe to get past 
> the moderator on repeater-builder
>  
> Ian
> G8PWE
>  
> 
> - Original Message -
> *From:* skipp025 
> *To:* Repeater-Builder@yahoogroups.com
> 
> *Sent:* Sunday, May 04, 2008 2:44 PM
> *Subject:* [Repeater-Builder] Re: antenna question - Dip It and
> Scotch Kote
> 
> I constructed a 6 meter beam some years back, worked like a bomb
> even at 25ft above ground elevation. To ensure my pride and joy
> would last a long time I sprayed it with clear Krylon brand spray
> paint.
> 
> The antenna was instantly unusable regardless of my efforts to
> remove the paint, re-tune or otherwise modify the antenna. I later
> learned that type of paint contained materials with a horible
> D-Factor. I was never able to use the antenna again, although it
> remains in my back yard as a reminder.
> 
> cheers,
> s.
> 
>  > "Chuck Kelsey" <[EMAIL PROTECTED]> wrote:
>  > Boy, you took a gamble. I'd have been afraid that this action
>  > could have either messed up the VSWR or shifted the resonant
>  > point of the antenna. Then again, maybe it did and either
>  > you don't know that or it wasn't significant.
>  >
>  > Chuck
>  > WB2EDV
>  >
>  >
>  > - Original Message -
>  > From: "skipp025" <[EMAIL PROTECTED]>
>  > To:  >
>  > Sent: Sunday, May 04, 2008 12:19 AM
>  > Subject: [Repeater-Builder] Re: antenna question - Dip It and Scotch
> Kote
>  >
>  >
>  > > Hi Robert,
>  > >
>  > > You might get lucky... because they might also have advertised
>  > > the dip-it as an insulator material, which means someone was
>  > > hopefully looking at the dissipation factor (aka D-Factor) when
>  > > the compound was engineered. Time will tell...
>  > >
>  > > cheers,
>  > > skipp
>  > >
>  > >> "georgiaskywarn"  wrote:
>  > >> Someone else told me that after I had put a whole can of dip
>  > >> it on the db408 I showed you. I went back and covered every
>  > >> inch of it with liquid electrical tape. I have had good
>  > >> results in the GA sun with it.
>  > >> 73,
>  > >> Robert
>  > >> KD4YDC
>  > >>
>  >
> 
> 

Re: [Repeater-Builder] Cooling fan

[Burt Lang]

I have found that adding a resistor in series with the fan and a 
capacitor across the fan will do the same job as an inductor and 
capacitor without taking up as much space.  The value of resistor I use 
is just enough to drop the voltage by about 1/2 volt.  For a fan drawing 
0.5A, use a 1 ohm 1W resistor. For other current draws adjust 
accordingly. It is not critical.  The fan speed will not change much - 
12vdc fans will run as low as 6-7v normally.

Burt  VE2BMQ

Captainlance wrote:
> *We have found that 12v. fans do cause interference with our link 
> transmitters for the NYC voting network. The solution we found is taking 
> one of the 2 power supply chokes from an old Micor mobile radio and 
> using it in series with the 12v. lead to the fan, add a cap. 2000 mfd or 
> larger from fan to ground and the level of AC imposed on the power lead 
> drops from nearly 4 VOLTS to less than 10 millivolts...Resulting in a 
> totally clean carrier. *
> *lance N2HBA*
> 
> - Original Message -
> *From:* Doug Hutchison 
> *To:* Repeater-Builder@yahoogroups.com
> 
> *Sent:* Saturday, April 26, 2008 4:48 AM
> *Subject:* [Repeater-Builder] Cooling fan
> 
> Hi,
> 
> Have tried a few ex equipment and CPU cooler fans on a p/a heatsink
> but all generate a noise (light buzz) on the transmitted signal.
> 
> Can anyone suggest the correct choice of fan (or what I am missing) to
> stop the buzz on the transmitted signal?
> 
> RF choke? Tried cap up to 4700uf little change?
> 
> Thank you,
> Doug - GM7SVK
> 
>

Re: [Repeater-Builder] Re: question about motorola t1500 series cans

[Burt Lang]

Delrin (polyacetal) is a bad choice for RF applications.  Its 
dissipation factor is too high.  It is a great "engineering plastic" 
meaning it is strong physically but it is too lossy.  Teflon (tm) is the 
best, also rexolite for RF.  Also most any ceramics.  Corning has a line 
of "machinable" ceramic if you can find it that works great for RF.

A good test for RF suitable plastics is to put them in a microwave oven 
and run it for 10-30 seconds.  If the plastic gets hot or even warm, it 
is unsuitable or a poor choice for RF.

Burt VE2BMQ

skipp025 wrote:
> Re: question about motorola t1500 series cans
> 
> The melting was probably done by high circulating current within 
> the duplexer cavity. Typical for this type operation. Replace the 
> plastic parts with a better (non-plastic) insulator with the proper 
> D-factor and you'd be able to rock and roll again using the same 
> bottle.  Delrin and certain grades of teflon are popular internal 
> insulators. 
> 
> Relative to the same size and types of T-1500 bottles, there 
> shouldnot be a lot of other things to go wrong inside the cavity. 
> 
> cheers, 
> skipp 
> 
> ps: don't forget to replace any plastic SO-239 coax connectors with 
> better quality parts. 
> 
>  
>> "Phil" <[EMAIL PROTECTED]> wrote:
>>
>> I have a set of t1500 series cans that i need to know if they are 250 
>> watt or 60 watt. How can i tell? Was wondering because i ended up with 
>> melted notch coupling insulators. I was running 75 watts to the 
>> duplexers.
>>
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Sinclair Q202G duplexer Conversion

[Burt Lang]

wpp3 wrote:
> Read the posts here already and wish to clarify a few things. First I
> am in the process of converting a Q202G from the 160mhz range down
> into the 2m band, specifically 144.7500/145.3500Mhz.  I have found
> that I will need to replace the harness to do this as it will not tune
> down that far.  
> 
> 1.  I Understand I must make the harnesses at 1/4 wavelength each
> between the cavities and from the cavities to the antenna "T"
> connector.   What is the formula for the exact cable length?  i.e. 1/4
> wavelength of freq * velocity factor of cable = cable segment length?

That is the proper formula but don't get too hung up on exact lengths.

> 
> 2. Are the lengths exactly the same for the low and the high sides or
> are they dependent on individual frequency for each side.

The lengths are not highly critical.  AFAIK Sinclair only had 2 standard 
harnesses, one for the low part of the band and one for the high part. 
The low split harness cables were about 1 inch longer each.

> 
> 3. Where is the measurement taken? From tip-to-tip of cable or from
> center-of-T to center-of-T, etc?

Between center of Tees.

> 
> 4. In relation to #3 I will be using a N-Male/UHF-Female adapter on
> each can. Then connecting the "T" to that adapter.  Will this affect
> the cable harness length calculations and if so how?

Maybe or maybe not the length of the cables.  However anything that will 
lengthen the distance between the center of the Tee and the loop will 
affect the tuning and depth of the notches.

Now the key question.  Why would anyone want to use a pitifully 
inadequate so-called UHF adapter or connector on a well designed system 
that is intended to have N type connectors.  Throw out all your UHF 
connectors and adaptors and go with the proper type N connectors.  Save 
yourself a lot a hassle later with problems related to the UHF connector 
series.

That is just my opinion based on past experience.  Others may differ.

Burt  VE2BMQ

Re: [Repeater-Builder] Remote power monitoring

[Burt Lang]

There is an another option.  PacComm had a 4 channel A-D converter board 
for their Tiny-2 TNCs.  It operated with the TheNet X1JR4 node software. 
Each of the channels had adjustable scaling to yield whatever numbers 
you wanted on the output.  It has been a while since I have been 
involved with packet but as I recall it would send out the info as part 
of a bulletin packet or possibly on request.  You would need a packet 
terminal to display the result.

I am not sure if the AD-4 is still available (it is mentioned on their 
website but not shown as a current product) but the actual circuit was 
quite simple and a diagram was available as I recall with the X1JR4 info.

Burt VE2BMQ

Mike Besemer (WM4B) wrote:
> I’m interested in remotely monitoring the power/SWR at the repeater site 
> and having the ability to have a macro poll the device and report status 
> over the repeater output.  I see that LDG makes a power meter with a 
> voice output that I could probably interface, but is there something 
> designed more specifically for the application I have in mind?  The 
> controller is a CAT-1000.
> 
> Ideas?
> 
> Mike
> 
> WM4B
> 
>  
> 
> 




 
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Re: [Repeater-Builder] Doubling Power Output On UHF Repeater

[Burt Lang]

I would halve the power, tell the users that you have doubled the power 
and watch the glowing reports of greatly improved performance roll in. :-)

That was the results I got 15 years ago when I tried the experiment.

Burt VE2BMQ

Tony L. wrote:
> I've asked this question before, but will ask it again just to see if 
> there are any new twists that I'm unaware of:
> 
> Our UHF repeater is currently equipped with a 50 watt PA.  We have an 
> opportunity to install a 100 watt PA at moderate cost.  Our site is 
> excellent and we are already using good radios, quality hardline, 
> excellent filtering, and a commercial grade antenna.
> 
> Will the difference between 50 & 100 watts be worth a moderate 
> expenditure?
> 
> What would you do?
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Sinclair Q-2B05D duplexer

[Burt Lang]

According to an old Sinclair datasheet, the 2B indicates a frequency 
range of 132-150 MHz, the trailing D indicates 3 in cans and the O5 is 
an engineering number.  Looking at Q-203D specs shows 3 MHz min spacing, 
0.6dB insertion loss and 65 dB isolation.

Hope that helps.

Burt Lang  VE2BMQ>>>

[EMAIL PROTECTED] wrote:
> Trying to find specs of the above. It appears to be abt. 20 yrs. old., 5 mhz 
> spacing ?? 
> 
> Any further info is appreciated. 
> 
> Jerry VE3 EXT
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] E.F. Johnson/Dataradio DL-3410 info needed.

[Burt Lang]

You might try Dataradio Inc.  They took over the EF Johnson data radio 
line as I recall.

www.dataradio.com/

Burt  VE2BMQ

kb4mdz wrote:
> Anyone have any info on alignment, etc. on a E.F. Johnson DL-3410 
> radio, Receiver or  Transmitter?   Got one of RX, two of TX, and am 
> trying to decide on suitability for  little g-job idea.
> 
> Thanks,
> Chuk G.
> kb4mdz
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Sinclair duplexer notches

[Burt Lang]

lpcoates wrote:
> Hi
> 
> I'm helping a friend who wants to convert a Sinclair Res-Lok 4 cavity 
> combiner into a duplexer.  Basically turning it into a Q2220E I 
> think).  As far as I can tell, it should be possible by simply adding a 
> vatialbe cap to the coupling loops.  I still haven't found the answers 
> to to two questions.
> 
> 
> 2. What determines the location of the notch?  two cavities will have 
> the notch above the pass band and the other two will have the notch 
> below the pass band.  I suspect there's something different about the 
> coupling loops but I don't know what.

There is no difference between the loops for hi side or lo side notches. 
  A loop with series capacitor will have 2 notches, one above and one 
below the pass frequency. On VHF they are separated by about 10 MHz. The 
capacitor shifts the pair of notches relative to the pass frequency. 
More capacity, lower notch freqs. A low pass notch needs typically 10-12 
pf and a high side 20-25 pf. You will need to use very hi Q capacitors. 
  On VHF the value of the capacitor should be 30 pf.  Sinclair use 
Johanson 5600 (or 5602) 1-30pf trimmers.  They are costly, typically 
12-15$ each and not readily available surplus.  An alternative is to use 
1-10 pf trimmers (Johanson 5200 series) in parallel. They are readily 
available surplus for $1 or less each. You would need two for a low pass 
notch and 3 for a high pass notch.

Warning:  Never use any trimmer that has a sliding or rotating contact 
in the RF circuit.  From experience they are almost guaranteed to cause 
noise problems. The Johanson trimmers use a bellows to make solid 
contact to the movable element.

Good luck in your project

Burt VE2BMQ>>

> 
> Thanks
> 
> Bruce
> VE5BNC

Re: [Repeater-Builder] Thanks, Alum Tape and Antenna...Tape part#?

[Burt Lang]

3M (or Scotch) 425 on 2 rolls of aluminum tape I have of different widths.

Burt VE2BMQ

Jeff DePolo wrote:
> I bought my last rolls of filament tape and aluminum tape from Tessco.  They
> were OEM'ed by 3M but sold as Decibel products.  If you can't find them,
> I'll see if I can get a 3M part number off them.
> 
>   --- Jeff
>  
> 
>> -Original Message-
>> From: Repeater-Builder@yahoogroups.com 
>> [mailto:[EMAIL PROTECTED] On Behalf Of Paul Finch
>> Sent: Friday, June 01, 2007 12:34 PM
>> To: Repeater-Builder@yahoogroups.com
>> Subject: RE: [Repeater-Builder] Thanks, Alum Tape and 
>> Antenna...Tape part#?
>>
>> 3M for the aluminum tape, bet it's on their website and you 
>> can fine a local
>> vendor from there.  The fiberglass tape you can get just 
>> about anywhere, the
>> tape DB used was like 1/2 inch wide so it would fit 
>> completely under the
>> aluminum tape.  I have used regular 3/4 inch fiberglass tape with no
>> problems though.
>>
>> Paul
>>  
>>
>> -Original Message-
>> From: Repeater-Builder@yahoogroups.com
>> [mailto:[EMAIL PROTECTED] On Behalf Of Preston Moore
>> Sent: Friday, June 01, 2007 11:25 AM
>> To: Repeater-Builder@yahoogroups.com
>> Subject: RE: [Repeater-Builder] Thanks, Alum Tape and 
>> Antenna...Tape part#?
>>
>> While on this subject.  Can someone please advise on the 3M 
>> part number for
>> the aluminum and the fiberglass tape?  I found the Decibel 
>> part numbers for
>> the tape, but would rather find another source.  I have a 420 
>> that needs the
>> harness reattached.  Also, any suggestions on a general 
>> cleaning of the
>> antenna?  I was thinking of steel wool or the like.  Anyone?
>>
>> Thanks
>> Preston Moore, N5YIZ
>>
>>
>>
>> __
>> __
>> 
>> Boardwalk for $500? In 2007? Ha! Play Monopoly Here and Now 
>> (it's updated
>> for today's economy) at Yahoo! Games.
>> http://get.games.yahoo.com/proddesc?gamekey=monopolyherenow  
>>
>>
>>
>>
>>  
>> Yahoo! Groups Links
>>
>>
>>
>>
>> No virus found in this incoming message.
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>> Version: 7.5.472 / Virus Database: 269.8.6/828 - Release 
>> Date: 6/1/2007
>> 11:22 AM
>>  
>>
>> No virus found in this outgoing message.
>> Checked by AVG Free Edition. 
>> Version: 7.5.472 / Virus Database: 269.8.6/828 - Release 
>> Date: 6/1/2007
>> 11:22 AM
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>>
>>
>>
>>
>>
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>>
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>> No virus found in this incoming message.
>> Checked by AVG Free Edition. 
>> Version: 7.5.472 / Virus Database: 269.8.6/828 - Release 
>> Date: 6/1/2007 11:22 AM
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> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Repeater to TNC

[Burt Lang]

I have not done it myself but a repeater in Montreal did hook up a 
Paccomm Tiny-2 TNC to do that application.  The TNC was loaded with 
TheNET X1JR4 node software and had an option to output the data on the 
serial port.  It also had the ability to control that function with a 
password to turn it on or off.

I used to be the packet Guru but it has been a while since I looked at 
the X1J documentation.  If you are interested, I could look it up.

Burt Lang  VE2BMQ
Past Tech chairman of the late NEDA (North East Digital Assoc).

knightdriver54 wrote:
> I was wondering if anyone in the group has ever configured a packet tnc 
> to a repeater controller for the ability to program it over the air via 
> a remote tnc. I have put the repeater tnc to transparent mode but it 
> does not seem to respond. Are there other setting that I need to set. 
> 
> Thanks to the group..
> 
> Until Next Time
> Steve
> N7hzs
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Sinclair Q202 tuning problem

[Burt Lang]

Keep in mind that there are two notches, one on each side of the pass. 
They are spaced about 10-15 MHz apart. When the low notch is at 146MHz, 
you will find the upper notch in the 154-156MHz area roughly. The reject 
coaxial capacitor (or the piston cap in the newer version) adjusts both 
notches in tandem.  To get a low pass can, you have to move the high 
notch down close to the pass band.  This takes more capacity in the 
reject capacitor.  You may even have to lengthen the center conductor in 
that capacitor to get it to tune low enough.

The proper length of cable harness may also help to lower the maximum 
capacity needed on the reject adjustment.

Good luck in your tuning

Burt  VE2BMQ>>>

kk2ed wrote:

snipped
> 
> The pass (146.200) tunes just fine, with 1.5db or so of insertion 
> loss, but reject is an issue. The cavities on the low side act as if 
> they are another set of high-side cans.  The reject rods appear to 
> tune properly, and I can get 80+db of rejection 600KHz low of 
> 146.200, but no matter what I do, the reject will never go ABOVE the 
> pass frequency. 
> 
> I doubt the cable harness lengths would cause this, no? From the past 
> posts I read, it sounds like if I were running out of room on the 
> reject rods, then the cable lenghts might be the issue. But my issue 
> is that the low side's reject is sitting below the pass, not above 
> the pass where it needs to be. 
> 

Re: [Repeater-Builder] Re: Duplexer cavity repair

[Burt Lang]

Burt Lang wrote:
> The 10pf would probably work for the cans where the notch is on the low 
> side of the pass ie hi-pass BpBr.  The capacity required for the notch 
> on the high side is 20-30 pf.  I have paralleled 3 of the 10pf caps 
> (which can be had surplus for $1 or so each) to replace the 30pf caps. 
> It does help when modifying it in this manner to have the proper tap for 
> the threads (15/64x64tpi).  It is not exactly easy or cheap to find such 
> a tap.
> 
> To explain the action of the capacitors, look at the wide response (+/- 
> 15MHz) of the can.  You will see that there are two notches, one on each 
> side of the pass peak. The notches are at least 10 MHz apart. The two 
> notches move in tandom with changing capacity. The more capacity the 
> lower the notches are.  With low capacity the lower notch will cosy up 
> to the peak.  In order to lower the upper notch down close to the peak 
> requires a lot more capacity.
> 
> Good luck with your tuning.
> 
> Burt VE2BMQ>>
> 
> tomnevue wrote:
>> snipped
> 
>> Now for general information, the nut is just a locking device and the 
>> capacitor is screwed into the threaded mounting plate. Also it was 
>> pretty easy to find Johanson hi-Q piston caps at 0-10pf which are about 
>> 1/4 inch shorter. I was curious to see if this was enough capacitance 
>> to resonate the loop at the right frequency, so I temporairly installed 
>> one of these. I added a strip of copper to take up the added length. 
>> With the 10pf capacitor it resonated well into the Ham band, but I'm 
>> sure it wouldn't make it down to the cavity lower spec of 137MHz. So in 
>> a pinch, I think the shorter 10pf version would probably useable for 2 
>> meters.
>>
>> Thanks again.  Tom
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] Re: Duplexer cavity repair

[Burt Lang]

The 10pf would probably work for the cans where the notch is on the low 
side of the pass ie hi-pass BpBr.  The capacity required for the notch 
on the high side is 20-30 pf.  I have paralleled 3 of the 10pf caps 
(which can be had surplus for $1 or so each) to replace the 30pf caps. 
It does help when modifying it in this manner to have the proper tap for 
the threads (15/64x64tpi).  It is not exactly easy or cheap to find such 
a tap.

To explain the action of the capacitors, look at the wide response (+/- 
15MHz) of the can.  You will see that there are two notches, one on each 
side of the pass peak. The notches are at least 10 MHz apart. The two 
notches move in tandom with changing capacity. The more capacity the 
lower the notches are.  With low capacity the lower notch will cosy up 
to the peak.  In order to lower the upper notch down close to the peak 
requires a lot more capacity.

Good luck with your tuning.

Burt VE2BMQ>>

tomnevue wrote:
>snipped

> Now for general information, the nut is just a locking device and the 
> capacitor is screwed into the threaded mounting plate. Also it was 
> pretty easy to find Johanson hi-Q piston caps at 0-10pf which are about 
> 1/4 inch shorter. I was curious to see if this was enough capacitance 
> to resonate the loop at the right frequency, so I temporairly installed 
> one of these. I added a strip of copper to take up the added length. 
> With the 10pf capacitor it resonated well into the Ham band, but I'm 
> sure it wouldn't make it down to the cavity lower spec of 137MHz. So in 
> a pinch, I think the shorter 10pf version would probably useable for 2 
> meters.
> 
> Thanks again.  Tom

Re: [Repeater-Builder] Re: need app note MC145158 for R100

[Burt Lang]

Barry, I sent you a note off-line about the AN980 note I found but no 
response. Maybe your anti-spam ate it.  So I will repeat it here.



I found my copy of AN980 but its title is "VHF Narrowband FM Receiver 
Design Using the MC3362 and the MC3363 Dual Conversion Receivers" dated 
1988.  It does not sound like what you were asking for.  Are you sure 
about the number?

I have an index of Ap Notes and bulletins dated 1989 and I don't see any 
reference to an "R100 PLL".  Can you give me a Motorola MCxxxxxx device 
number?

Burt Lang>>>

Barry Buelow wrote:
> The data sheet I have lists only AN980.
> 980 may cross ref others..
> 
> Barry
> 
> 
> 
> 
> 
> 
> --- In Repeater-Builder@yahoogroups.com, Burt Lang <[EMAIL PROTECTED]> wrote:
>> Do you by chance have an AN- number?  in the 1980s I used to 
>> subscribe to all the Motorola documents and still have most of them
> in a 
>> box.
>>
>> Burt  VE2BMQ>>>
>>
>> Barry Buelow wrote:
>>> Hello
>>>
>>> Does anyone have a copy of the Motorola App NOtes for PLL from about
>>> 15+ years ago?  I'm looking for some info on the R100 PLL.  I have a
>>> data sheet but the App Notes had much more useful info.
>>>
>>> I'd take a scanned pdf, paper, whatever..
>>>
>>> Thanks,
>>> Barry  w0iy

Re: [Repeater-Builder] need app note MC145158 for R100

[Burt Lang]

Do you by chance have an AN- number?  in the 1980s I used to 
subscribe to all the Motorola documents and still have most of them in a 
box.

Burt  VE2BMQ>>>

Barry Buelow wrote:
> Hello
> 
> Does anyone have a copy of the Motorola App NOtes for PLL from about
> 15+ years ago?  I'm looking for some info on the R100 PLL.  I have a
> data sheet but the App Notes had much more useful info.
> 
> I'd take a scanned pdf, paper, whatever..
> 
> Thanks,
> Barry  w0iy
> 
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 

Re: [Repeater-Builder] LMR feedline revisited and revised!

[Burt Lang]

Hi folks

I have heard that the military will not allow BNCs on RF connections 
because the bayonet connection on the outside shell allows the ground 
side of the cable to vary (wiggle) and be noisy.  BNCs appear to be used 
for data and low freq but TNCs are specified for RF use.

Some years ago a local club was having trouble with their homebuilt 
duplexor that used BNC connectors on the cable connections.  The 
duplexor became noisy intermittantly.  Move the cables and it would 
quiet down for a few days but would always return.  I suppled them with 
equivalent TNC connectors for the duplexor and they never had trouble 
again from that source.

The standard PL259/SO239 combo has an impedance of approximately 35 
ohms.  If the insulation is removed from the SO239, the impedance is 
close to 50 ohms.  I did see a Japanese wattmeter (I think it was Yaesu) 
that had insulatorless SO239s on it.

One problem with the PL259 that I have not seen mentioned is that it is 
not weatherproof and the ground connection is problematic at best. It is 
very easy to tighten the shell and then find it loose because the 
"teeth" on the PL259 were not bottomed into the notches in the SO-239.

Just my 2c for what it is worth.

Burt  VE2BMQ>>

Eric Lemmon wrote:
> Allan,
> 
> That's a good question!  Both "N" and "BNC" connectors vary the dielectric
> thickness, and the spacing and diameter of the center and shield elements,
> so that the swept impedance seen by a Time-Domain Spectrometer (TDR Test
> Set) shows no variation in characteristic impedance through the connector.
> When a "Constant-Impedance" connector is installed  in a
> transmission line, its presence will not be revealed when swept with a TDR
> Test Set.
> 
> The infamous PL-259 plug, when mated with the matching SO-239 jack, is far
> from constant impedance.  Even the most basic TDR Test Set can detect the
> impedance "bump" where UHF connectors are used.  Where the impedance is not
> constant, unwanted parasitic oscillations can occur, which means that
> intermodulation and spurious signals have a fertile breeding ground.
> 
> Moreover, the ideal RF transmission system comprises cable and connectors
> that present a uniform 50-ohm impedance, without any significant bumps or
> dips.  This cannot be achieved with RF connectors that do not have constant
> impedance.
> 
> 73, Eric Lemmon WB6FLY
> 
> 
> -Original Message-
> From: Repeater-Builder@yahoogroups.com
> [mailto:[EMAIL PROTECTED] On Behalf Of allan crites
> Sent: Thursday, March 22, 2007 7:57 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: RE: [Repeater-Builder] LMR feedline revisited and revised!
> 
> I sure would like to hear what you all mean by " constant impedance ".
> Allan Crites, WA9ZZU
> 
> 

Re: [Repeater-Builder] DC Power Supply Test Load

[Burt Lang]

Another possibility are 12v RV incandescent lamps.  A 50w lamp will draw 
4 amps.  Hook a bunch of sockets in parallel and screw in the number of 
lamps necessary for the desired load.  The light will remind you that 
the load is still connected and you don't need a cooling fan.

Another advantage of this arrangment is the more stable current vs 
voltage curve.  When the tungsten filament cools at lower voltage, the 
resistance drops and it allows more current to flow than if it was a 
pure resistor.  The current change with voltage is about half as much as 
with a pure resistor ie 10% lower voltage will drop the current by 5%. 
Just like the old Amperite ballast tubes that were used on some radios 
like the R390 to stabilize filament voltage.

Burt  VE2BMQ

Re: [Repeater-Builder] Effects of doubling RF output on UHF repeater?

[Burt Lang]

If you ever do install the amp, I would suggest lying to the users when 
it goes on line.  Tell them that it is on low power when it is on high 
and vice versa but don't announce it the instant you change. Wait a 
while before announcing it.  You will very quickly find out who can 
actually tell the difference.  At least that is what we found about 20 
years ago when we did a major rearrangement of antennas and lowering 
power.  Nobody honestly could tell the difference and those who agreed 
with our false conditions were shown to not have a clue (I never did 
tell them what the experimental results were :-)

Burt VE2BMQ>>>

Tony L. wrote:
> 
> 
> One of our 70cm Amateur Radio repeaters is currently outputting 50
> watts into the duplexer. We're considering replacing the existing RF
> power amp with a 100 watt model.
> 
> Current draw on the 50 watt unit is 8 amps. The 100 watt unit will
> draw 20 amps. Our power supply is rated at 36 amps continuous, and
> the duplexer is rated at 250 watts.
> 
> Half of our users believe that the repeater's output power is
> perfectly matched to its receiver. That is, users of high powered
> mobile radios generally lose repeater reception at about the same
> time the repeater's receiver loses them.
> 
> However, the other half of our users believe doubling the repeater's
> power output would generate increased activity since the repeater
> could be heard more "comfortably."
> 
> We could upgrade without changing any of our other infrastructure.
> However, these questions arise: 1) Will the hundreds we pay to
> upgrade actually translate into significantly increased range? 2)
> Will we risk generating additional receiver noise by doubling our
> output power, thus losing coverage in the process? 3) Will using a
> higher power level shorten the life of other system components over
> time (e.g., power supply)?
> 
> By the way, our frequency coordination would be valid even if we
> doubled our output power.
> 
> 

Re: [Repeater-Builder] Re: Power Supplies going up in smoke (non filtered)

[Burt Lang]

Hi guys

I have bought a number of the Lambda modules at fleamarkets usually for 
a dollar each or so.  There are two sizes, a low power one designed to 
fit onto the 5-7 amp supplies and a high power one designed for the 24+ 
Amp supplies.  The differences are mainly in the size of the SCR.

I have the datasheet including schematic for the Lambda OVP adjustable 
modules.  If you want a scan or pdf, I could probably supply it for the 
files.

Burt VE2BMQ>>>

skipp025 wrote:
> 
> 
>  > [EMAIL PROTECTED] wrote:
>  > Unfortunately, I got a reply from Samlex saying the OVP is
>  > of a feedback type, not a crowbar, which explains Jeff's experience
>  > with the SEC-1212.
> 
> Not so good...
> 
>  > A long time ago I happened to find a crowbar "bar" made by Lambda
>  > at the local TRW swap meet. I added it to a supply without built-in
>  > OVP to add said protection to the equipment.
> 
> I have seen a number of small crow-bar pc daughter boards tacked
> onto various "Power One" (a brand name) type power supplies. They
> are easily copied or even lifted off the original supply for use
> in other locations.
> 
>  > I wonder if similar devices are commonly available somewhere?
> 
> They are but nothing comes to mind right away... You might check
> with Kitsrus, Jameco, Electronics Rainbow, Marlin P. Jones and a
> few other kit mfgr/retailers to see what they offer. If not I can
> and would share some of my notes if you want to "roll your own".
> 
>  > That & a fuse on the output of an SEC-1223 & I think
>  > I'd feel comfy using it at one of my sites.
>  > Bob NO6B
> 
> The key points are location, function & size. Where will the crowbar
> be placed? What will the crowbar do to everything on the dc bus at
> a fault condition? What happens after the fault condition goes
> away and or remains? Does the crow-bar device/circuit have a
> large enough capacity.
> 
> Astron designed their crowbar circuit to short the supply output.
> The shorted output protects the user equipment and tries to
> force the AC Mains fuse to open through excessive transformer
> primary current draw.
> 
> The bad news is found when modest size power supply - ac mains
> fuses are replaced with excessive large current values (the trusty
> 25 or 30 amp 3ag fuse everyone seems to have a lot of...). Not
> enough current draw through the faulted secondary side of the
> supply to open the wrong size installed ac mains fuse.
> 
> Somethings got to give... and it's often very hot when it does.
> 
> cheers,
> s.
> 
> 

Re: [Repeater-Builder] Re: Sinclair Q2B05D Duplexer

[Burt Lang]

 From the length of the cans, they cannot be straight 1/4 wave 
resonators. That length is more like the length for UHF cans. They must 
be either heavily capacitively loaded or helical resonators.  Either way 
they will not be suitable for narrow split.  The specs on a Q-205D 
standard model show a overall length of 22in and they have a 3 MHz min 
spacing and 65 dB attenuation.

Burt Lang VE2BMQ


Laryn Lohman wrote:
> 
> 
> --- In Repeater-Builder@yahoogroups.com 
> <mailto:Repeater-Builder%40yahoogroups.com>, Burt Lang <[EMAIL PROTECTED]> 
> wrote:
>  >
>  > What length are the cans? According to Sinclair's old "Duplexor
>  > nomenclature" from a 1973 datasheet, that the 2B indicates a 132-150
> MHz
>  > range. The O5 are "Engineering numbers" and the D = 3in cavity size.
>  > Does any of that make sense?
>  >
>  > Burt VE2BMQ>>
> 
> The cans are 11in long and 3in square. (The 4in cavity size
> originally posted wasn't correct.) The nameplate indicates it was
> tuned to TX 142.770 143.085, and RX 138.750 139.005. Yes, apparently
> a range of frequencies for each.
> 
> Any ideas on tuning and specs?
> 
> Laryn K8TVZ
> 
> 

Re: [Repeater-Builder] Sinclair Q2B05D Duplexer

[Burt Lang]

What length are the cans?  According to Sinclair's old "Duplexor 
nomenclature" from a 1973 datasheet, that the 2B indicates a 132-150 MHz 
range.  The O5 are "Engineering numbers" and the D = 3in cavity size. 
Does any of that make sense?

Burt VE2BMQ>>


Laryn Lohman wrote:
> 
> 
> I am looking for specs and tuning info for this unit. I have searched
> the RB site but I have not found the info needed. This unit consists
> of 4 cavities about 4in square. It is VHF. Can anyone help?
> 
> Laryn K8TVZ
> 
> 

Re: [Repeater-Builder] Stuck cores - Back on Topic

[Burt Lang]

One technique that I have used occasionally has not been mentioned yet.

Assuming the the core has a hex hole in it, you choose an metal hex key 
(allan wrench) of the right size to fit the core and heat it very hot 
with a torch.  Then place the key in the core and let the heat transfer 
to the core.  After a few minutes, very carefully and gently try to turn 
the core.  If it turns, then remove the metal key  and use the normal 
plastic tool to remove it.  If that does not free it, then try something 
else.  If it is already cracked, the metal key with slip in the core in 
which case drill it out or replace the whole coil.

Burt  VE2BMQ>>>

Eric Lemmon wrote:
> 
> 
> 
> Since many coil forms have a waxy surface, it often helps to direct a flow
> of very warm air around the form while applying slight torque with the
> proper tuning tool. I made an adapter nozzle for my Weller heat gun that
> allows me to direct the hot air to a small area, without heating adjacent
> components. This usually works, but I then must use a wire brush to clean
> the threads of the core, which now have melted wax in them.
> 
> 73, Eric Lemmon WB6FLY
> 

Re: [Repeater-Builder] Whale Tale for late November

[Burt Lang]

or a 22 caliber cartridge!!!  According to the Darwin Awards, someone 
actually tried that.  It didn't kill him but his ability to transfer 
genes in the future was severely limited :-)

Burt  VE2BMQ>>

Chuck Kelsey wrote:
> 
> 
> How about an aluminum foil gum wrapper wrapped over a fuse. I've seen that.
> 
> Chuck
> 
> - Original Message -
> From: "Mike Morris WA6ILQ" <[EMAIL PROTECTED] 
> >
> To:  >
> Sent: Thursday, November 30, 2006 4:04 PM
> Subject: Re: [Repeater-Builder] Whale Tale for late November
> 
>  > At 11:43 AM 11/30/06, you wrote:
>  >
>  >>The question is... who's time and money should it be?
>  >
>  > Time and materials - you had to diagnose and repair
>  > the customer's incompetent "repair" - they need to
>  > replace the fuse with an identical one, not a
>  > "better" one.
>  >
>  > They are paying for your demonstrated competence,
>  > and if slow-blow fuses were better you would have
>  > used them... You used a fast blow fuse to protect
>  > their investment.
>  > If they don't value the equipment they purchased from
>  > you, and paid you to install, they can put a piece of
>  > copper rod in place of the fuse (and yes, I've found
>  > two of them).
>  >
>  > Mike
>  >
> 
> 

Re: [Repeater-Builder] White Noise on Two Meters.....

[Burt Lang]

Any spread spectrum systems nearby??

Burt VE2BMQ

Gary wrote:
> I have an interesting thing happening on our two meter repeater.  We 
> have what appears to be a blanking white noise that is present on the 
> input.  The repeater is a split site system with a 440 link from the 
> two meter receiver site over to the transmitter site about 2000ft 
> away.  There are no duplexers in the system to cause problems.
> 
> The link on 440 is clean of any noise, so we are quite confident the 
> link is not a problem.
> 
> On two meters, when a signal is anything less than full quiteing, we 
> get a white noise that will almost mask the audio.  We have tried 
> different receivers such as the GE MVS and now a GE Master II.  We 
> have removed the preamplifier with minimal results.  The receivers 
> have excellent sensitivity and the tuning process of the receivers is 
> correct.  We have also tried putting pass cavities ahead of the 
> receiver with no appreciable change.  The antenna is a DB-224 mounted 
> on a broadcast tower just below the bays of an FM broadcast 
> commercial transmitter.  We have turned OFF the fm broadcast 
> transmitter at times to check if perhaps this was the problem but no 
> change was noted.
> 
> ANY IDEAS from anyone???
> 
> THANKS!
> Gary - W5GNB




 
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Re: [Repeater-Builder] Sinclair Q 202G Tuning Problem

[Burt Lang]

What you are experiencing is the symptioms of insufficient capacity to 
pull the notch down low enough on the low pass side.  The capacity range 
of those "tuning stubs" is determined by the length of the center rod 
inside the plastic stub. They are 3/16 (I think) diameter brass rod with 
a threaded end. Sinclair had several lengths available, the longest one 
being about 6in long. There is probably nobody left at Sinclair that 
even remembers that part as that design dates back to the 1950s or 60s 
and was superseded by the Johanson trimmer design in the late 1960s. You 
should be able to get a local machinist to make you a longer one using 
the one you have as an example.

Burt VE2BMQ>>>



Jim Brown wrote:

> I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz 
> range and have run into a problem on the notch tuning.  The high pass 
> tuning works like a charm and has a good pass and notch characteristic.  
> The low pass side is another story.  The pass tuning works fine, but I 
> can't get a notch.  With the tuning rods all the way in, it is starting 
> to notch, but only about 20 db.
> 
> Here is the strange thing - I took the coupling loop out of the high 
> pass side and compared it to the low pass side, and they are identical.  
> The tuning rod varies the capacitance across the single loop connector 
> and there is no inductance in the circuit for either high pass or low 
> pass side.  How does the same hookup work to allow a notch on the low 
> side as well as the high side?
> 
> I am tempted to add a small fixed capacitance across the loop to see if 
> that helps the tuning for the low pass side..
> 
> Any comments on which way to go?
> 
> 73 - Jim W5ZIT
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 




 
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Re: [Repeater-Builder] Harris mobile unit

[Burt Lang]

You say a drawer??  I have a manual on a "Harris CT-1555 VHF/FM car 
telephone".  According to the spec sheet the FCC approvals on the RX and 
TX modules are the same 1555A1.  If it is in a drawer, maybe it is some 
kind of a remote base or something operating in the same MTS or RCC 
phone system with the same modules as the mobile.

Burt  VE2BMQ>>>

wa8ili wrote:

> Have a Harris drawer with tag: FCC tx/rx 1555A1. Can anyone id this 
> unit, vhf/uhf? Thank,Bernie
> 
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 




 
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Re: [Repeater-Builder] A sad story

[Burt Lang]

Is it the interconnect cable that is heating or is it the can that is 
heating and transferring heat to the cable?

I had one case of a Sinclair duplexor where one can was heating at least 
20 deg warmer than the remaining 3 cans.  It turned out to be a lossy 
ground connection where the center resonator attaches to the end of the 
can.  Cleaning the mating surfaces solved the problem completely.  That 
part of a can is where the RF current is maximum (voltage is minimum) 
and any resistance will cause excessive loss and heat.

Just a possibility to consider.

Burt VE2BMQ>>


Dave VanHorn wrote:
> It all started when we went up to replace a failing antenna, and a 
> mess of adaptors..
> 
> The antenna is a GP-9 that had some water in it, and was slowly 
> turning into a dummy load.  I'd had the UHF system running into it 
> through the band coupler with the VHF system, but I could see the 
> output on both systems getting weaker, and I was worried about SWR 
> into the UHF amp, so I commanded that system offline a couple weeks 
> ago.
> 
> Then I got the flu, and the weather was nasty..
> 
> Friday, with clearing weather and head, we went up, thinking that 
> after we replaced the antenna and adaptor mess, we could put the uhf 
> system online.
> 
> Antenna replacement went well, and then I replaced the adaptor mess 
> with the 6" cable I made from BNC male to N male, replacing a handful 
> of adaptors that I'd kludged into the system originally, to make the 
> distance and two 90 degree bends that were required.  This is the 
> adaptor mess that was getting hot.
> 
> Now the new cable is in place, and that power that was getting turned 
> into heat is getting delivered to the cans. But, something smells 
> funny, and the interconnect cables between the cans are noticably 
> warm.
> 
> I need to go back up there, and pull the amp and cans, and see what's 
> going on.. 
> 
> I'm just kind of disgusted.
> These are Wacoms, I don't have the exact model number in front of me, 
> but if I remember right, they were rated for 150W or thereabouts. I 
> had tuned them before, and everything was looking good, but it 
> appears that when the adaptor chain wasn't in the picture sucking up 
> power, I crossed some threshold and damaged the cans.
> 
> Anyone seen something like this?  What are my prospects of repairing 
> these cans?
> 
> 
> 




 
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Re: [Repeater-Builder] Re: Best broadband VHF antenna

[Burt Lang]

The SRL235 series with its double dipoles side by side on each side of 
the mast doesn't have any connection with the SRL210 series unless it is 
in the way that the feedline is terminated at the element (the picture I 
see in their catalogue looks like an internal termination like the 210 
dipole).  I would not trust any antenna with the side by side dipoles to 
give a good smooth pattern.  Our experience with SRL210 and 310 antennas 
has been excellant.

The SRL222/224 lines appear to be a cheap version to compete with the dB 
222/224 antennas.

Burt  VE2BMQ>>>

Chuck Kelsey wrote:

> Nope, the 235 is in the same family as the 210. The 210 family is a good 
> line.
> 
> The 222/224 does not have a boom that holds the element away from the 
> mast. Instead, the element is attached right at the mounting mast and 
> has some sort of funky hairpin type matching configuration.
> 
> Chuck
> WB2EDV
> 





 
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Re: [Repeater-Builder] Best broadband VHF antenna

[Burt Lang]

Sinclair 210C4 speced at 138-174<1.5:1  They are the standard antenna 
used in multicoupled systems here in Canada.  I have seen one with as 
many as 28 frequencies coupled into it.

Burt  VE2BMQ>>

[EMAIL PROTECTED] wrote:
> 
> Have a question for the list.  Is there an antenna (VHF) that will cover a 
> 30mhz bandwith?  (Reasonably)  
> 
> There is a system in Georgia incompassing the entire state using various tall 
> towers.  On the towers will be antennas that will be used for VHF Repeaters 
> and VHF digital. (in the ham band)  T
> 
> he NWS is hoping to use the same antennas on a "Mesonet". (like this one 
> http://www.mesonet.ou.edu/)  They are looking at the government freq.s right 
> now but thinks there may be something in the 175mhz band.  
> 
> 
> Will this work?  I suggested the db224, but I see it's bandwith is only 
> 10mhz.  I do realize these will work out of band pretty well (using a db224 
> for a remote base antenna and a db420 on a repeater now)...but just wasn't 
> sure if there was a better choice.
> 
> Thanks,
> Robert Burton
> DEC NWS in Peachtree City,GA
> www.georgiaskywarn.com
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 




 
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Re: [Repeater-Builder] Sinclair Duplexer Replacement Capacitor

[Burt Lang]

It is a Johanson model 5602 1-30pF.  They are not easy to find and 
expect to pay 10-15$ for one.

At times when I needed a replacement, I modified the disk to take 3 
Johanson 5202 1-10pF trimmers in parallel which are much easier to find 
cheap.  They may even be higher Q than the single unit but I have not 
been able to prove it.

Burt  VE2BMQ>>

Bill Ockert wrote:
> Good Afternoon,
> 
> I have a Sinclair Model 202G duplexer in which one of the insertion 
> loops has a bad (cracked) piston capacitor.  Has anyone had occasion 
> to replace one of these and if so what did you replace it with?  
> 




 
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Re: [Repeater-Builder] Mystery 2M cans

[Burt Lang]

They are definitely Sinclair, welded top, side loop BpBr cans.  They are 
an intermediate design between the old rounded top, spun aluminum cans 
with side loop and the welded top, top adjustable loop design of the 
modern Sinclair cans.  They date from the late 50s or early 60s (by 1964 
or so the top adjustable loop design had been adopted).

The stub hanging down is a coaxial capacitor that tunes the notch.  The 
cable going up would connect to the side of a Tee connector with the 
signal path going thru the Tee connector.  That cable will be an 
electrical 1/4 wave at the pass frequency although it is not super 
critical.  They could also be part of a hybrid ring design although the 
can is the same regardless of the type of filter.

Try them on the tracking generator over a much wider range (like 
130-160MHz)  You should see two notches, one above and one below the 
pass.  If you want a HPLR you will have to reduce the capacity of the 
coaxial capacitor stub considerably.  That will move the low side notch 
up closer to the pass.

Good luck in your experiments.

Burt  VE2BMQ>>>
Scott Zimmerman wrote:
> Fellows,
>  
> I bought these cans at Dayton last year. I have no information on them. 
> The interconnecting harness is butchered pretty badly, so I'm not sure 
> of the correct lengths. I'm hoping that someone can recognize these and 
> has some documentation and / or a set that we can use as a pattern.
>  
> I think these are Sinclair, but I'm not sure. Kevin and I have put them 
> on the tracking generator and have been able to get LPHR response out of 
> them, but not HPLR. I think this is due to not having the correct cable 
> lengths.
>  
> Thanks in advance for any info and to you dial-up subscribers, sorry for 
> sending pictures you may not need.
>  
> Scott Zimmerman
> Repeater-Builder (the company)
>  
> Scott Zimmerman
> Amateur Radio Call N3XCC
> 612 Barnett Rd
> Boswell, PA 15531
> 




 
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Re: [Repeater-Builder] Generator question

[Burt Lang]

Yes, it is the same as 5W-30 except that in extreme low temps it does 
not thicken up nearly as much. All synthetic oils have a much flatter 
viscosity vs temp curve.  I have used full synthetic 5W-30 in my truck 
ever since I got it and it would start easily at -40(F or C) without any 
block heater. On a small generator with a tecumsuh motor, I could hardly 
turn it over at 10F using regular 10W-30.  With the synthetic 0W-30 it 
would turn over with not much difference in effort on the pull cord than 
if it was at summer temps.

Burt>>>

Chuck Kelsey wrote:
> Is it safe to use in the summer?
> 
> Chuck
> 
> Burt Lang wrote:
> 
>>Try using 0W-30 fully synthetic oil in the crankcase.  I find that that 
>>does not thicken nearly as much as regular 5W-30 oil in my generator.  I 
>>can normally spin it easily even at -20.
>>
>>0W-30 synthetic is not easy to find but I did find some at Wal-Mart in 
>>the past and Esso has some called ZERO oil that the farmers around here 
>>use on their tractors in the winter.
>>
>>Burt  VE2BMQ>>>
>>
>>Chuck Kelsey wrote:
>> 
>>
>>
>>>Guys,
>>>
>>>I have a 5KW natural gas generator at my house to serve as backup power 
>>>to not only the house, but it keeps a repeater and my ham shack up and 
>>>running.
>>>
>>>During  cold weather, it doesn't like to start (manual start, pull 
>>>cord). I fund that if I place a halogen work light pointed at it for 
>>>about 10 minutes, it warms it up enough so it will start OK.
>>>
>>>My question is -- does anyone know of a small engine block heater out 
>>>there? I've done Google searches and don't really find anything 
>>>worthwhile. No, I don't what to use a light bulb. I want something 
>>>that's safe, economical to operate and UL approved.
>>>
>>>Chuck
>>>WB2EDV
>>>
>>>
>>>
>>>
>>>
>>>
>>>Yahoo! Groups Links
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>   
>>>
>>
>>
>>
>>
>>
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>>
>>
>> 
>>
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 




 
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Re: [Repeater-Builder] Generator question

[Burt Lang]

Try using 0W-30 fully synthetic oil in the crankcase.  I find that that 
does not thicken nearly as much as regular 5W-30 oil in my generator.  I 
can normally spin it easily even at -20.

0W-30 synthetic is not easy to find but I did find some at Wal-Mart in 
the past and Esso has some called ZERO oil that the farmers around here 
use on their tractors in the winter.

Burt  VE2BMQ>>>

Chuck Kelsey wrote:
> Guys,
> 
> I have a 5KW natural gas generator at my house to serve as backup power 
> to not only the house, but it keeps a repeater and my ham shack up and 
> running.
> 
> During  cold weather, it doesn't like to start (manual start, pull 
> cord). I fund that if I place a halogen work light pointed at it for 
> about 10 minutes, it warms it up enough so it will start OK.
> 
> My question is -- does anyone know of a small engine block heater out 
> there? I've done Google searches and don't really find anything 
> worthwhile. No, I don't what to use a light bulb. I want something 
> that's safe, economical to operate and UL approved.
> 
> Chuck
> WB2EDV
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 




 
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Re: [Repeater-Builder] Re: [Tower-pro] Gensets stolen

[Burt Lang]

A few years ago a couple of large gensets were stolen from a 
construction site here in Quebec.  6 months later the police raided a 
farm a couple of miles from me and took down a marijuana grow-op.  Seems 
the gensets had been equipped with what is locally known as a 
"Boomerang" system, a commercial vehicle theft alert system using GPS 
and cellphones.  As soon as the operators turned one of the gensets on 
to power the lights in the greenhouse, it phoned home and told its 
owners where it was.  They found the second one in the barn - a spare 
backup I presume. :-)

Burt  VE2BMQ>>>

skipp025 wrote:
> In California... construction crews will chain up 
> a genset and hoist it into the air 60 feet when 
> the crew isn't working.  The crane is disabled so 
> the load can't be lowered. 
> 
> You drive by on the freeway and do the classic 
> double take to see a few tons of portable genset 
> at the end of the crane cable up some 60 feet. 
> But the equipment is there when the crew gets 
> back to work on Monday (most of the time). 
> 
> cheers, 
> skipp 
> 
> www.radiowrench.com/sonic 
> 
> 
>>Neil McKie <[EMAIL PROTECTED]> wrote:
>>
>>
>>  ... forwarded ... 
>>
>>Blake Bowers wrote:  ( [EMAIL PROTECTED] ) 
>>
>>>"The Radio Shop" in Seminole OK has had two
>>>gensets stolen, one 36kw Generac, in a Microvan
>>>shelter (Shelter stolen also) and a second genset,
>>>make unknown, with no shelter but an outdoor
>>>enclosure.
>>>
>>>Gensets were stolen from Pauls Valley OK, and
>>>Wayne OK.  (Pauls Valley had its waveguide stolen
>>>in early 2002)
>>>
>>>At the Wayne site, they drug the shelter out of the
>>>compound, down the driveway of the neighbor, before
>>>picking it up.
>>>
>>>For any information, or if you have any information,
>>>please email.
>>>
>>
> 
> 
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 




 
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Re: [Repeater-Builder] Air Variable Capacitors for DB4060

[Burt Lang]

The Johanson 30 pf trimmer is very rare in surplus but the 10 pf 
trimmers are very common and cheap (as little as 50c-$1 each) in 
surplus. I have bought a few hundred over the years, mostly at 
fleamarkets. I have used 3 10pf trimmers in parallel to replace the 30 
pf trimmers in Sinclair cans.  Depending on the mounting arrangement 
that may also work with the DB cans.  Also the 10pf unit has a much 
higher Q than the 30pf trimmer and paralleling them MAY give a higher Q 
than the single 30pf unit.  From experience it is certainly no worse.

Richardson Electronics also sell Johanson but their minimum qty is 100 
pces.  Electrosonic in Toronto used to distribute them but no longer 
have the account.  The single unit price for the 5602 should be in the 
$15 range.

Don't be tempted to use trimmers that have a sliding or rotating 
connection to the rotor such as the Johnson air trimmers.  I tried that 
one time and the rf currant thru the joint caused noise and instability 
reflected back to the transmitter.  The Johanson trimmer uses a bellows 
connection from the moveable element to ground that is a solid but 
flexable connection.

Just some hints from years of modifying and making cans in my shop.

Burt  VE2BMQ

Mike Besemer (WM4B) wrote:
> Greetings all,
> 
> I need two air variable capacitors for our DB4060 cans.  I contacted the
> company who bought out DB Products and was informed that they don't sell
> parts... but if they did, the price would be $41 each for the caps!
> 
> The caps are Johanson 5602 (www.johansonmfg.com) 1 - 30 pf air variables.  I
> requested a quote from Arizona Components Company and one other place, but
> expect the get the 'we don't sell in small quantity' response.  Google
> hasn't been much help either. 
> 
> Does anybody have a couple of these in your pocket or know where I can get
> my hands on a couple of them.  What about ideas for suitable subs?  
> 
> -- de WM4B
> Mike
> Kathleen, GA
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 




 
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Re: [Repeater-Builder] 6 M Gain Antenna

[Burt Lang]

Hi guys

With all this talk about 6m antennas, can I mention that I have a pair 
of Sinclair SRL-110 dipoles to dispose of.  They were used in a 
commercial system at 48/49 MHz.  I have not tested them at 52/53 MHz but 
the SRL-x10 series antennas are usually quite broadband.

The catch is that they are large and I don't want to ship them anywhere. 
  So pick-up only - near Montreal, Quebec.  If interested, contact me 
off-list.

Burt  VE2BMQ>>>






 
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Re: [Repeater-Builder] Re: Various Cooling Methods

[Burt Lang]

Some years ago I acquired some multiplex telephone linking equipment 
made by SR Telecom Inc. here in Canada.  It operated around 1400 MHz as 
I recall but that is not important.  These units were installed in 
completely sealed, cast aluminum outdoor enclosures.  To remove the heat 
from the final stages, they used a heat pipe.  It consisted of a length 
of copper tube sealed at both ends and about one half of its length 
partially flattened.  The other half had a large number of copper fins 
attached to the tube.  There was a gasketed disk attached to the center 
that searved to seal the connection where the heat pipe passed thru the 
wall of the enclosure.  The flattened end of the heat pipe was clamped 
against the bottom of the final amp assembly with some heatsink compound 
to ensure good thermal contact.

I don't know what the working fluid in the heat pipe was but someone 
suggested it was just water operating in a partial vacuum to lower the 
boiling point.  It could be any liquid with a suitable boiling point and 
a high latent heat of vaporization.

For those who don't know the principles of operation of heat pipes, let 
me explain briefly.  A heat pipe is just a sealed tube partially filled 
with a working fluid, and containing a wick that passes from one end to 
the other. There may also be an expansion chamber to relieve the 
increased pressure when the fluid is heated. When one end is heated, the 
working fluid is vaporized  and the vapor flows to the cold end where it 
condenses.  The liquid is then forced back to the hot end with the wick. 
  No moving parts to wear out, it can never get colder than the ambiant 
air of the cold end (hence no condensation), it is totally silent and is 
quite inexpensive.

It is far more efficient than an equivalent length of solid copper. 
Tests using infra-red photography shows that when heat is applied to one 
end, the whole length of the tube rapidly becomes warm, 10 to 100 times 
faster than a solid copper bar of the same diameter.

There endith the lesson for today :-)  Have fun with your experiments.

Burt VE2BMQ>>>

Dave VanHorn wrote:
> At 01:35 PM 6/4/2005, Alexander Tubonjic wrote:
> 
> 
>The first thing that comes to mind is how to dealing with the
>condensation created during the heating and cooling of the
>>
>>refridgerant.
>>
>>  What if you were to place the radio vertical with the heatsink
>>facing the ground and place a drip pan under the radio? Condensation
>>on the heatsink shouldnt effect the performance of the radio? Same for
>>the power supply, just mount it upside down with the heatsink facing
>>the ground.




 
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Re: [Repeater-Builder] OT- Cushman CE5

[Burt Lang]

Is the scope in the CE5 a plug-in model 301 module?  If so, the CRT is a 
3RP1A tube.  If not that module, please disregard.

Burt  VE2BMQ>>>


hwingate wrote:
> 
> The CRT display in my old CE5 has gotten so dim that I have to turn
> the lights off to use it. Does anyone know the CRT tube number used in
> it so I can start looking for one? (It is much easier asking than
> taking it apart and looking !!)
> 
> 
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 




 
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Re: [Repeater-Builder] db 4001 to 220

[Burt Lang]

As a general rule, the outer can has to be at least a can radius longer 
than the center resonator  ie a 6 in can must be at least 3 inches 
longer than the resonator.  There is no maximum length requirement on 
the outer can.

Burt  VE2BMQ>>

Jeff DePolo wrote:

> Probably not.  You would run into problems if you were extending the center 
> conductor; as you get closer and closer to the "bottom" of the cavity you 
> get more and more capacitance off the end of the center conductor as its 
> lengthened.  But obviously that's not the case here.
> 
> If you haven't modified the loops yet, you may find that you need to.  
> 
> --- Jeff
> 
> 
> 
> On Fri, 18 Feb 2005 01:01:22 -0500, Thomas Oliver wrote
> 
>>Needed a bandpass cavity for 220 not having one I modified one by 
>>shortening the inner plunger and the outer conductor. My question is 
>>do I need to shorten the outer cavity?  I don't think it makes any 
>>difference what do ya think? I would like to know before I rivet it 
>>back together.
>>
>>tom n8ies
> 
> 
> 
> 
> 
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 




 
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Re: [Repeater-Builder] Converting a Pass filter

[Burt Lang]

I don't know what a 74-70 is - my old TXRX catalogue does not list it. 
But I have converted a TXRX 4 can multicoupler to a 2m BpBr Duplexor for 
a local club quite successfully.  I will discuss it with you off-list if 
you are interested.

Burt  VE2BMQ

wa9ba wrote:
> 
> I was wondering if anyone has had any luck converting a TX RX 74-70 
> Pass filter to a Reject? I tryed looking in the archives but is so 
> time consuming.
> Bill
> 
>




 
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Re: [Repeater-Builder] Sinclair Q2330E tuning problems

[Burt Lang]

Per Molund wrote:
> 
> I am trying to retune an Sinclair Q2330E duplex filter to 145 MHz 
> (145.1375/145.7375) from it's factory configuration of 150 MHz 
> (150.83/149.80), however the notch atenuation is strongly reduced. 
> There is also impossible to set ut the proper bandpass/notch 
> separation. 

What you are describing has all the symptoms of too much coupling in the 
loops.  Try reducing the coupling of the loop in one can and see if it 
makes it easier to tune the notch closer to the pass and if the notch is 
deeper.  If so, keep reducing the coupling until the notch depth is 
optimized.  Repeat on all the cans.

> I noticed fron the Q2330E specification sheet that the duplexer can 
> be ordered for 132-150MHz og 148-174MHz, anyone know how I can 
> determine which version I have on hand? I would assume the high 
> frequency version can give this problem if I try to adjust it to 145 
> MHz?  

There should be no problem tuning the 148 version to 145 MHz.  The main 
difference between the two versions would be a longer resonator (and 
possibly a longer outside can to accommodate it) and slightly longer 
cables.  The cables are not highly critical as to frequency from my 
experience.

> Can I assume the difference between the two versions are the cavity 
> loops and the cable harness? 
> 
> best regards,
> 
> ---per
> LA9XKA
> 

Good luck in your project.

Burt  VE2BMQ>>>




 
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Re: [Repeater-Builder] Outlet for RG214/U

[Burt Lang]

How much do you need?  Does anyone know what it is worth on the market 
as I have 600-700 ft that may be surplus to my needs.  I will have to 
hunt it up and check the type number.

Burt  VE2BMQ

DCFluX wrote:

> Anyone know where I can get 1/4" hardline? Either Super Flex or Regular?
> 
> 





 
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Re: [Repeater-Builder] Sinclair

[Burt Lang]

I assume that this duplexor is the model with rotatable loops on the 
flat welded end of the cans (as opposed to an earlier model with side 
loops and rounded can ends).  From my experience, if the loops are too 
tightly couplied, it is difficult to get the notch close to the pass. 
Try reducing the coupling by rotating the loop.

Burt  VE2BMQ>>>

[EMAIL PROTECTED] wrote:
> Has any in the group had any experience with tuning Sinclair duplexers 
> model Q-202C?  The problem we are having with them is tuning them for a 
> 600 KC split,  146.775 and 146.175. We can get one side to tune up to 
> 146.775 and the other only to 145.800. The specs for these duplexers 
> show that they should go to a 500 KC split without any problems. The 
> person tuning these has the experience and the lab equipment to the job.
> Thanks for any help in advance
> Mike





 
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[Repeater-Builder] Ignition Noise suppression

[Burt Lang]

Someone asked about suppressing ignition noise in the fuel pump noise 
thread.  There was a discussion of this subject in one of the repeater 
groups back some years ago.  One poster indicated that he had excellant 
results with Magnacor CN series ignition wire sets.  They are pricey 
like 150-200$ a set but apparently work better than anything else on the 
market.  See their web page at:

http://www.magnecor.com/magnecor1/main.htm

and look for the CN series info.

Note: I have no experience with them - I am just reporting what I 
remember was shared with the group at that time.  I believe the poster 
had a GM truck that was particularly bad for ignition noise and the 
Magnacor wires cured it completely.

Burt VE2BMQ>>>





 
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Re: [Repeater-Builder] VHF repeater and APRS on same antenna?

[Burt Lang]

Hi Adi

At VE2RM (Rigaud, QC) we have been doing that since 1986 with a 145.01 
digi on the same antenna as our 146.400TX/147.000RX repeater.  Spacing 
is similar to what you want to do.  We are using a clone of a Sinclair 
C-series multicoupler (3 6in pass cans and one notch can) that is 
installed in the feedline between the antenna and the duplexer.  There 
is about 65dB isolation on 146.40 and a lot more on 147.00 with about 
0.5dB insertion loss thru the multicoupler to the repeater.  In your 
system your receiver would be closer to the digi than ours but I think 
it is do-able although you have to be careful of the skirts on the notch 
can.  I configured ours with a non-symetrical skirt on the passband to 
avoid interfering with the 146.400 TX power.

Contact me off-line if you need further info.

Burt VE2BMQ>>>

Adi Linden wrote:

> Hi Eric,
> 
> The VHf repeater is 146.850 TX and 146.250 RX. The simplex APRS frequency 
> is 144.390. There is just a single duplexer installed. Six round cans from 
> Sinclair. Power output of the repeater transmitter is 25W.
> 
> Running a digi on 144.390 would be the preferred option. However, if that 
> is not easily possible, how about just running a 144.390 receiver on the 
> same antenna? There is a good possibility that site may have network 
> access later this year.
> 
> Adi




 

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Re: [Repeater-Builder] Off topic questions

[Burt Lang]

I think the original question was about a Jones  or Cinch-Jones plug.  I 
have a large number of various sizes.  Which one was being looked for?

Burt VE2BMQ>>>





 

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Re: [Repeater-Builder] Looking for a 2 meter cavity Duplexer.

[Burt Lang]

The name INVAR was coined by the man who discovered it, a Mr Guillaume,
and is not a tradename.  The main manufacturer of INVAR is Carpenter
Steel Co.

I just checked with the Metals Handbook, 8th Ed, published by the
American Society of Metals, Volume 1, chapter on low expansion alloys
and Inconel is not mentioned anywhere in the discussion which is quite
extensive and complete.  Inconel is discussed in the chapter on High
Temperature alloys and no mention is made of any unusually low
temperature coefficient of expansion.  Just because it contains nickel
does not make it like invar.  Stainless contains nickel and its
expansion is almost identical to common steel, brass and other common
metals.  INVAR is an anomoly with low expansion that occurs only at one
specific concentration of nickel.  The low coefficient is affected by
almost any other metal added to the alloy.  In INVAR the total
concentration of all other metals (besides iron and nickel) is less than
1%.

There are some other low expansion alloys that contain some cobalt (a
very expensive alloying component) such as Super Nilvar, Kovar, Fernico,
Fernichrome and Elinvar but they are usually used for special
applications that can tolerate the higher cost.

So be very careful about recommending substitutes for INVAR.  If you
want low expansion, there is no effective substitute.

Burt VE2BMQ>>

Virden Clark Beckman wrote:
> 
> If you can find an outfit in your area that does heat treating, see if
> they can find a product called inconel, it is a nickel rich low carbon
> alloy - you will find it works almost as good as invar, which I think
> was trade-named by the db company, back ??
> 
> Matt Krick wrote:
> >
> > On a related note, Does anyone know where I can get 1/2" solid Invar 36 rod 
> > in 24" long segments?
> >
> >
> >
> > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> 
> --
> 73...Clark Beckman N8PZD
> 
> 
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/



 

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Re: [Repeater-Builder] Looking for a 2 meter cavity Duplexer.

[Burt Lang]

I have used Advanced Alloys in Deer Park, NY in the past to get Invar.

http://www.advancedalloys.com/

Look under Corrosion Resistant and High Temp Alloys - Rod  for Invar36
(Invar is 36.15% nickel, remainder iron)

Normally rod is stocked in 12 ft lengths but they cut my orders to 6ft
so that it could be shipped UPS.  I am sure they would cut it to
whatever you want - for a charge.

But be prepared to pay $20/lb or more (maybe a lot more as I was buying
back in the 80s).  Why do you need 1/2in rod.  All the cavitys I have
seen have used 5/16 or 1/4 in dia rod except low band that used 3/8 dia.

Burt  VE2BMQ>>>


Matt Krick wrote:
> 
> On a related note, Does anyone know where I can get 1/2" solid Invar 36 rod 
> in 24" long segments?
>



 

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Re: [Repeater-Builder] Re: crystal alignment (how accurate is accurate)

[Burt Lang]

You don't even need an S-meter.  The background noise level will vary
inversely with the signal level and as you approach zero beat, the noise
will flutter slower until it rises and falls very slowly. It is just as
accurate as using an S-meter. I have used that technique many times on
my freq counter timebase.

Burt VE2BMQ>>

"Robert D. Mantell" wrote:
> 
> It never fails - pose a simple question, and you get a series of overly
> complicated answers involving
> expensive equipment.  To calibrate a local frequency standard, one needs
> a short wave rx with an
> s meter (mechanical type), and a means of balancing the local standard
> signal level with that of WWV
> at 10 MHz.  All you need to do is adjust the local standard while
> watching the s meter.  As it is
> adjusted, you will notice the s meter flutter at a decreasing rate as
> you reach 10 Mhz.  When you
> are dead on, the s meter will drift slower and finally stop.  You are
> there.  And please, do not argue
> about doppler, selective fading, etc.  Sure you will be able to see
> these effects, but they will not affect
> the accuracy of this operation.  Just watch for the response when the
> WWV or whatever signal is steady.
> 
> I hope this helps
> 
> Bob - W3TGG
>



 

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