from:"Tom"

One solution to the receiving problem when using high current relays may 
be to have dc current (eg 100mA) pass through the contact in RX. This 
would be particularly easy to implement when the antennas are zero ohms at 
DC because the dc current source can then be placed in the shack (with a 
suitable choke to isolate the RF from the supply and capacitor to isolate 
the DC from the rig).


That's a good suggestion, and I looked at it for amplifiers, but it is 
impractical in some cases because of the "pop" it makes when the contacts 
switch. I can live with it for casual operating, but the AGC pump up kills a 
short signal while the AGC recovers. 


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Re: Topband: TX relays


Hi Mike,

The contacts are not gold-flashed, that's just the lighting and 
reflections

that makes it look that way in the photos. They are a cadmium-free silver
alloy. Here's the data sheet.


Silver is a poor material for most environments without wetting currents 
because of sulfidation. It is certainly better than cad contacts, but 
ideally contacts should be gold flash for maximum reliability in receive 
applications. Of course TX power will break down the sulfide, and restore 
receiving.



But, this discussion does not answer Milt's original question, because he
wants a DPDT relay. :-)
He said "I am looking for some 12 VDC units that are capable of handling
full legal limit power to install in a controller for a multi-element
directive array." Maybe we can get back on track here.


To pick a relay, one usually has to understand the system in some depth. 
Milt has an unusual system in that his system has inactive elements that are 
in an area of intense local field levels connected through odd quarter wave 
feedline. The system has to disable the unused elements without having 
excessive voltages across open contacts.


The impedances at the common point are also nowhere near 50 ohms, and we do 
not know the voltage distribution.


Without knowing open circuit voltage levels and operating voltages and 
currents, I couldn't possibly make a suggestion. What works in my system are 
the DXE smaller relays, but my system is entirely different than Milt's.



I have a half-dozen sealed 12VDC DPDT relays that I am going to use (among
other things) to switch the low-Z sections of my remote tuner/band switch.
They're rated at 8A and have 5 kV insulation (and maybe that's
conservative) between coil and contacts. I'm pretty confident they will
handle the legal limit even with a little mismatch. (And these are not for
any receiving application here.)


The dc or hot switch current rating has little to do with how they work at 
30 MHz, and we have no idea what the operating parameters in Milt's system 
are. I know the requirements are different from my directional antennas, but 
that is all I know.


I need a clutch for my home made car. It has four tires. What clutch will 
work? Give me a part number. Same thing, if you see what I am saying.


73 Tom



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Re: Topband: TX relays

Tom still hasnt answered why there is only a $10 price difference between 
the RCS-4 and the -8V yet users of the -8V are getting raped for 
replacement relays.




I don't know why any public forum allows you to post the vitriol nonsense 
you post.


Do you ever do anything in life besides insulting others or picking fights? 


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Re: Topband: TX relays




What would be a better choice for a stack match?

I'm quite sure that in the heat of a contest these things have been hot 
switched on rare occasion with 1500w.  There was one time when I 
intentionally hot switched one of them with 100w because I thought the 
receive signal was down 10dB or so.  Problem went away.  Anyway I've been 
using them for about 6 years or so and only had one that failed after a 
big lightening strike.


Stan, K5GO



Hi Stan,

There is a direct opposition between a contact able to take an intense arc 
in switching and a contact that is low resistance and maintains low 
resistance without "wetting" (wetting is a significant steady voltage that 
burns off the micro-thin sulfide and contaminant layer).


I'm sure there is stuff on line by relay manufacturers. Relay contact issues 
on receive are probably the number one problem manufacturers face. This 
might not show in a stack switch because the receiver will often receive 
through some path, even if the stack connection is not what it is on 
transmit. The same is true for directional arrays, where an element or two 
might drop from the system on receive, and the operator be unaware it is 
even happening.


Receive drop out problems like this might be masked in a stack or 
directional switch, but they are clearly evident in an antenna selector 
switch and in an amplifier antenna transfer relay. Since there are not 
multiple receive paths to some portion of the antenna system, they go 
completely dead. In a stack or directional array, you just lose pattern. The 
operator is just not aware of the problem because it is not hitting him in 
the head with a 2x4.


You really don't want to hot switch anything with RF. It is not only rough 
on the relay, it is rough on gear.


There are two ways to handle most systems. It is possible to build a small 
external box that disallows hot switching. It is also possible in some cases 
to build the relay box in a way that does not permit open contact 
conditions, which is called a "make before break" system.


Most of the control stuff I'm involved with has hot switch protection. The 
DXE 4 square controller, for example, disallows switching while the TX 
control line is low. It switches when the TX line is high, but locks off the 
amplifier relay control line for a preprogrammed time until the relays have 
time to settle. It also cycles the relays repeatedly and rapidly on initial 
power-up to wipe contacts.


The RCS 12 Ameritron does the same for hot switch. The RCS12 not only locks 
out hot switching, it locks out the wrong band. If an RCS12 is connected to 
band data from the radio it could provide automatic band antenna selection 
plus stack selection on one box, and include hot switch lockout.


I load my contest station with RCS12's so operators cannot pick the wrong 
antenna for the band, and so they cannot hot switch. They can actually 
change antennas by stabbing a button during transmit, and the RCS12 holds 
off the transfer until the TX drops. When TX drops it opens the amplifier 
control line, and then transfers the relay. After the relay transfers it 
allows amplifier use again. This way someone cannot pick the wrong antenna, 
and they cannot transfer a relay while the amplifier is on line.


When I design a stack box or any relay system, one of my considerations is 
to try to not permit wiring or contact conditions that allow open transfer 
loads on feeders in the relay box itself. This is called make before break 
operation. Sometimes this complicates the relay system, but it improves life 
in the field. Often it is not possible, but I generally spend some time 
trying to find a way to do this on any new projects. It is sometimes 
possible with a stack box and other switching, but it is impossible with an 
antenna transfer relay without greatly increasing cost.


The end result of this is usually increased cost, which causes people with 
dysthymic disorder to publically vent, but in the long term it is better to 
make a system more difficult to break. It is a bigger PITA for me to have to 
go out and change a board with 10 or 15 relays because of operator error 
than it is to just prevent the problem.


73 Tom 


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Re: Topband: TX relays

I have built four or five "stack matches" using these relays and have been
quite pleased with them.

http://www.mouser.com/ProductDetail/TE-Connectivity/T92S11D22-12/?qs=%2fha2pyFadujQKxyiQ9QJsU9gOmzykpctnwthD3xoZjoJPHbNrun4hw%3d%3d

73...Stan, K5GO

If you look at the contact material, it is the wrong material type for our
applications. Those relays are hot switch relays for high current
applications with Silver Cadmium Oxide. From an engineering bulletin on
selecting relay contact materials:

Silver Cadmium Oxide

Silver cadmium oxide contacts have long been used for switching loads

that produce a high energy arc. Silver cadmium oxide contacts are less

electrically conductive than fine silver contacts, but have superior

resistance to material transfer and material loss due to arcing. They do

exhibit greater interface resistance between mated contacts, and also a

slightly greater contact assembly heat rise. The minimum arc voltagerating

of silver cadmium oxide is 10 volts and, like fine silver contacts, the
silver

in this alloy will oxidize and sulfidate. Therefore, an arc is necessary to

keep these contacts clean.

This doesn't mean they won't work and will go up in smoke. It does mean they
are subject to contact sulfidation which causes intermittent receive. They
have silver, a hard base material, and large contact area that does not wipe
well. They also are the type of relay that is subject to contact derating
from skin effect because of constant resistivity.

73 Tom

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Re: Topband: TX relays




Between contact and coil. I just took 2 photos:
http://www.w0btu.com/files/misc/Omron_relay_G2R-1-E-T130/



This is where dissection helps. We can see, from the pictures, that relay is 
likely a good relay.


1.) It has wide smooth current paths. It does not have wire leads

2.) It has good spacing and insulation from contacts to the coil and metal 
outside the contacts


3.) It appears to be, although I am not certain, a gold flash.

Gold (real gold flash) is ideal for the receiving end as long as it is not 
hot switched or arced. Silver is not. Some silver alloys are worse still, 
and materials that appear in relays designed to be hot switched at high 
current are terrible in our applications (unless we only transmit).


When people burnish contacts, they rub the gold off. This is why a WD40 
wetted hard paper is about the most abrasive thing that should ever be used 
as a cleaning tool.


There is a problem with relays enclosed in plastic, like the picture. The 
plastic can leech contaminants that spoil the connection at low currents. 
Brand new relays exhibit this issue. Usually it clears and eventually stays 
OK once some very small current is passed through the contacts.


This is a frustrating problem for new equipment, because the relay can be OK 
in testing until it sits a while.


73 Tom 


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Re: Topband: TX relays


OK Carl and Jim,

I know you want one-part-number-fits-all answers, but I do not think that is 
possible. There are tens of thousands of relays and dozens of applications.


I am afraid telling people what to do in no uncertain terms by specifying a 
part number often winds up being wrong over time as things change.


For example a few years ago a very good Struthers-Dunn high power relay 
moved to China. The internal wire that used to handle several amperes on ten 
meters now heats and melts at half that current on upper HF. The root of 
this problem is the RF specs we are concerned with as amateurs have little 
or no bearing on the 60Hz or dc relay specs, so they didn't change a thing 
for relay operation in the published low frequency or dc specs, but rendered 
it useless at radio frequencies. When a manufacturing process changes, an 
off-the-shelf relay that had good RF performance can suddenly radically 
change.


This is why manufacturers that actually use relays in large quantity, while 
some of the more "grumpy" among us might think are unfairly making money 
through sinister secrecy, are usually better sources. They do the 
consistency checking for us. Some of the relays are custom. For example, the 
RCS8V uses a custom tooled relay that has a double make double break 
contact, or form X contact. It isn't under a part number at Mouser.


73 Tom



On Thu,10/9/2014 6:46 AM, Tom W8JI wrote:
Because there are many things that go into relay selection that do not 
show on a data sheet, I always dissect and test relays.


Thanks for an excellent exposition of the issues. Now how about the other 
half of the question -- part numbers for relays that meet the need? This 
reflector (and the spirit of ham radio) is about SHARING information.


73, Jim K9YC
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Re: Topband: TX relays

I just popped the cover off a little Omron PCB-mounting relay that I 
forgot

I had, rated at 10 kV. The spacing between the SPDT contacts and the coil
actually looks greater than that open-frame relay. I was thinking of
seriesing the contacts on two of these relays, if necessary.



If you series the contacts the voltages across open contacts divides by the 
capacitances between the contacts and everything around the contacts.


It is like connecting a bunch of unequal value capacitors in series without 
using any equalizing components to force equal voltage division.


I know we can find claims in a few articles of how well that works. In the 
actual world we live in, it does not actually work very well at RF without 
compensation to equalize voltages. 


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Re: Topband: TX relays

Because there are many things that go into relay selection that do not show 
on a data sheet, I always dissect and test relays.

I have found 30 amp power relays that overheat at 5 amps at 28 MHz, and 
relays that have high contact voltage ratings that make the pole inside the 
coil hot with full RF. They wind up with 20-30 pF capacitance from armature 
to coil.

Another issue is resistance and reliability at near zero contact voltage 
when receiving. This is probably the single biggest relay issue in our 
applications. A small bifurcated contact relay is better for receive 
reliability, and a high current hot switch design is by far the worse for 
receive reliability.

One particularly troublesome high power area for current are the relay 
internal leads, and the contact support bar materials. The things that make 
the wires and contact bars last a long time in repeated cycles create very 
high radio frequency resistances. This is why some large 30 amp power relays 
will discolor contacts or melt insulation at several amps on higher 
frequencies.

The same thing applies to contacts. Contact materials and platings that 
optimize hot switching create RF resistance and low level signal connection 
issues.  A gold flash on a soft contact, for example, is excellent for 
receive but will instantly deteriorate if hot switched at more than a few 
hundred milliamperes or with an inductive load. It might handle 20 amps of 
closed contact RF current, but only be rated for a few amps of hot switching 
current. In contrast, a silver cadmium oxide contact can take tons of hot 
switch voltage and current, but is lousy for relay receive pass through.

Contact support bars, and the wires used in some relays, can also be very 
problematic. This is because the materials and any weave in wires is 
designed for flexibility. Alloys and construction that improves mechanical 
cycle life greatly reduces RF performance.

> Mike, I would be concerned about using these small relays for 
non-resonant

antenna switching where the impedance at the switch point may be wildly
away from 50 ohms.

This is the relay I use to switch tuning networks at non-50-ohm points:

http://www.deltrol-controls.com/products/relays/power-relays/900

Deltrol is the brand you get if you order from McMaster-Carr but all the
big relay manufacturers sell these open frame relays.

I also bend the relay contacts for wider spacing as recommended by N6RK in
QST (page 66, May 2009 QST Hints and Kinks, "Increasing Relay Voltage
Handling"). Open contact gap of 0.5 inches is readily achievable.

Tim N3QE

On Thu, Oct 9, 2014 at 6:19 AM, Mike Waters  wrote:

This relay looks exactly what I was looking for to remote-switch my 160m
inverted-L to other bands, because it will withstand a lot of voltage. 
From

the PDF:

High insulation
Insulation distance (between coil and contacts): 10mm min.
Dielectric strength: 5KV
Surge strength: 10KV

73, Mike
www.w0btu.com

On Thu, Oct 9, 2014 at 2:23 AM, Thomas PA1M  wrote:

>  Fujitsu FTR-K1CK012W
>
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Re: Topband: 160M/80M Vertical - Using a capacity hat below a trap

2014-10-01 Thread Tom W8JI


I’m finalizing design for my 160M/80M shortened wire tree-mounted
vertical.  An Unadilla 80M trap will be
placed approx. 65’ feet above the feedpoint; above the trap is another 20 
feet

with a small cap hat.  An autotuner
handles the Z matching for the anticipated 500 watts on both bands.

QUESTION: Can one install a capacitive hat directly below
the 80M trap to help shorten the length of the 80M section?  For example, 
shortening the 80M radiator to
60’ (from 65’) and making up ‘the difference’ with a capacity hat?  Any 
downside?



The only downside of adding capacitance below the trap is the chance of 
increasing capacitance across the trap and changing trap tuning. If you just 
keep the loading hat or wire away from the section above the trap, you 
minimize that effect.


You really want the trap slightly up out of the 80 meter band to minimize 
trap losses.


Almost anything can appear to work OK, but technically a trap of given 
components handles the least power and has the highest loss when it is at or 
very near resonance. If you did the trap resonance for 3.65 MHz, loss would 
peak and power capability would be minimum right around that frequency. The 
trap would have reduced loss and higher power rating as frequency moves away 
from 3.65.


The loading wire or hat below the trap actually can decrease loss and 
increase power rating of the system, so it isn't a bad idea if you also 
minimize coupling to the area above the trap.


73 Tom 


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Re: Topband: 160 GP Choke

2014-09-29 Thread Tom W8JI

If it were my system, I would use an air core choke like you posted and 
ground the feedline where it reaches earth.


The nice thing is you can install the choke right at ground level with no 
ill effects at all.


Cheap, simple, and clean. It will work as well as anything else you can do 
and be very reliable.


73 Tom


- Original Message - 
From: "Cqtestk4xs--- via Topband" 

To: 
Sent: Monday, September 29, 2014 12:49 PM
Subject: Topband: 160 GP Choke



Thanks to all who responded.

One of the suggestions was to wrap about 40-45 turns of RG8X mini  on a 
PVC
core with a diameter of 4 incheslightweight and easy.  Part  two was 
to

ground the braid of the feeder line coax at the point where it  reaches
ground level.

What do you think?

Bill K4XS
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Re: Topband: 160 ground plane choke

2014-09-28 Thread Tom W8JI


Bill,

Models and measurements show, with four full size radials and 1500 watts, 
you can have a few hundred volts RMS between the radial common point and 
earth. That voltage, of course, increases with non-resonant radials.


In an uncontrolled or undefined application, where a person has no idea what 
is really going on, the only choice is to either overkill with extremes or 
just throw something in there and see how it works.   This is a very 
controlled impedance situation, which is great. We have some idea of what is 
on each side of the choke and of voltage driving the choke.


There are two ways to approach this, by grounding or with a choke.

The best way to handle it depends on your resources, what you prefer 
appearance wise, and the physical layout.


1.) If the antenna is out away from noise sources and things it might 
bother, and if the coax is in the air away from things, you can simply 
ground the feedline shield fairly well 1/8th to 1/4 wave from the radial 
common point. This will do exactly what any choke will do. The shield will 
look like a high impedance at the radials, and minimize current flow.


2.) You can ground the coax right below the antenna feedpoint, and insert 
some form of common mode choke between the shield's earthed ground and the 
antenna feedpoint. This choke can be an air core coil of coax at ground 
level, or a ferrite sleeve balun, or something wound on a core. You probably 
have a few hundred volts there driving the choke's impedance, so you have to 
consider that with cores.


This is not a critical system by any stretch of the imagination, and an 
air-core coil will work just fine (as would proper feedline suspension and 
grounding), but what you need really depends on what you want to do and what 
you have available.


It would become progressively more critical if you had fewer radials, no 
matter what magical type of counterpoise it might be. One radial would be 
much worse to decouple, and one short radial could be horrible to decouple. 
You have an easy system with four resonant radials.


If it were mine, I'd just break out the PVC 4" pipe and maybe 50-70 feet of 
RG8X for an air choke, and a few copper pipe ground rods.  I'd do that 
because of lightning around here, and because it would as well or better 
than anything else I could do.


73 Tom






- Original Message - 
From: "Cqtestk4xs--- via Topband" 

To: 
Sent: Saturday, September 27, 2014 9:50 AM
Subject: Topband: 160 ground plane choke



I've been using a 160 GP with 4 radials.  It's a Tee-top  supported with a
rope between two towers, with the top around 165 feet and the  base at 70
feet.  I'm feeding it with RG8X to keep the weight down on  the rope which
supports it.

Although it works well I would like to negate any loading which  might be
taking place on the feed line which drops from straight down from  the 
base.

Any ideas for a cheap, easily made, effective choke on the  feedline?

Bill K4XS/KH7XS
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Re: Topband: Remote pre-amp power source

2014-09-25 Thread Tom W8JI


Something to keep in mind

Even in a quiet location with a -10 dBd gain very directional antenna, the 
preamp can be thousands of feet from the antenna on 160 with no ill effects. 
My eight vertical array, for example, has about 600 feet of F6, then 2000 
feet of F11, then the preamp. It limits on propagated noise even in 
daylight.


Of course there are things that might make a remote amplifier useful, such 
as very lossy feedlines and very low gain antennas, but even 3000 feet of 
F11 type cable between antenna and preamp isn't an issue with normal 
antennas. What might be an issue is a compact loop or other very negative 
gain antenna.




- Original Message - 
From: 

To: "Don Kirk" 
Cc: "Topband" 
Sent: Thursday, September 25, 2014 2:55 PM
Subject: Re: Topband: Remote pre-amp power source




Hi Don,

Pre-amp requires 12-18 volts at 130ma. (low band DXing- nightime use)

This solar charger puts out 20 volts that could be reduced to 15 volts 
with a three legged regulator. I was hoping to find a pre-assembled 
charger & battery, but may have to build one.

http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html

73
Bruce-K1FZ

  What is the operating current and voltage of the preamp you plan to 
use? Since it sounds like the preamp will be powered on all the time this 
information will be key in the selection of the battery capacity and solar 
panel rating.

Don (wd8dsb)

On Thu, Sep 25, 2014 at 1:30 PM,   wrote:

  Anyone using, or know of a source, for a compact battery with solar 
cell charger, to power a remote antenna pre-amp ?

73 Bruce-K1FZ
www.qsl.net/k1fz/pennantnotes.html

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Topband: BCB Interference

2014-09-23 Thread Tom Boucher

Rather than use a filter capable of handling the transmit power, surely a 
better solution for the K3 would be to use a separate 160m receiving antenna, 
via a small filter on the BNC auxiliary antenna input.

73
Tom G3OLB
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Re: Topband: ROKU 3 QRM

2014-09-19 Thread Tom W8JI

Nearly all lower frequency noise ingress and egress is from differential 
mode of different cables entering and leaving a device.


Any individual cable or wiring by itself might be common mode or 
differential mode, but the nasty stuff that isn't filtered almost always is 
from two or more cables or wire groups that are excited in "push-pull" at 
the device.


This makes external wiring look like a big loop or big antenna system, so 
even small noises can go a long distance.


The very first thing I do is get one of those multiple port lightning 
arrestors or surge protectors and make sure every cable and wire leaving a 
system passes through that common point and everything that can be grounded 
or bonded or bypassed is bypassed with that "protector" as a common point.


73 Tom



- Original Message - 
From: "Dennis W0JX via Topband" 

To: 
Sent: Thursday, September 18, 2014 3:41 PM
Subject: Topband: ROKU 3 QRM



Topbanders:

Within the last 3 to 4 months, I have been plagued with very strong QRN. I 
have a two way beverage that party runs over my garage and next to the 
house but it had always been an excellent performer in the past. However, 
in the reverse direction the QRN was intense, well over S-9 while about 
S-5 in the forward direction.


Today, I decided to track the source down. I though it might be the new 
neighbors who moved in to the south since the beverage points southwest at 
their home. However, I decided to start inside my own home first. I set 
the QRN for S-9 on my K3 and began unplugging devices. It only took three 
attempts! When I pulled the power on the relatively new ROKU 3, the noise 
level on the K3 dropped from S9 to S5, about 24 db!


I then plugged in the ROKU power supply thinking it might be a switcher 
but the noise did not rise so it is coming from the ROKU 3 itself. Our 
previous much older original ROKU did not do this.


Now I'm going to have to deal with the XYL who is addicted to watching TV 
series on the darn thing! Any ideas on how I can shield, isolate, or 
modify this thing without causing a major operational issue?


By the way, the noise output of the ROKU declines with an increase in 
frequency. On 80 meters, there was a slight increase in noise but not 
signficantly so and no effect on 40.


Lesson learned: ALWAYS start your search inside your home first.

73, Dennis W0JX
Milan, Ohio
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Re: Topband: Outdoor rope suggestions

2014-09-17 Thread Tom W8JI


In about 7 years that Dacron stuff starts to dry out and comes apart
slowly, Rots it in water like rain gutters.



Perhaps you are confusing it with something else, or you bought some fake 
Chinese forgery?


Dacron rope (a trade name for a polyester rope derivative with less stretch 
than nylon)  is rated everywhere as being excellent for UV resistance with 
good or excellent chemical resistance, mildew resistant, and good abrasion 
resistance.


It is commonly used as a marine rope. I have some that has been up for 15 
years in Georgia sunshine, and it was used when I installed it!


There are some inferior ropes out there. I bought some Wal-Mart Nylon rope 
that had no UV resistance at all. It lasted less than a year, while other 
Nylons last many years. The Wal-Mart made in China Nylon rope was more like 
polypropylene.



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Re: Topband: WTB: Guy wire stuff

2014-09-05 Thread Tom W8JI

I would expect the regular grip to not fail, as you tested, because it is rated 
at 100% of 1/4 inch EHS breaking strength. Normally companies will not rate it 
that way without a huge safety margin.

The somewhat longer "big grip" styles, according to PLP, were only for added 
protection in cases where the guy lines had twisting or unwrapping issues. It 
was never even available in 1/4 inch until tower companies started selling it.

The real danger is in doing things seriously wrong, like putting the loop over 
something with inadequate radius. I've seen some pretty poor installations. 
Some installers slip the loop over the tower leg, or worse yet, over the leg 
plus a brace rod end. The rod puts a real sharp bump against the grip.


 
  - Original Message - 
  From: Wayne Kline 
  To: Carl ; JI Charles ; low bad reflector 
  Sent: Friday, September 05, 2014 1:16 PM
  Subject: RE: Topband: WTB: Guy wire stuff


   Just my  .02   
   
  Some call them Tomatoes some call them Tomottos  
   
  but even those fruits come in different size and texture  .
   
   
   When I built my station @ this QTH  4 guyed towers  with broken up guys  502 
insulators and
   
  a PRE Formed guy Fasteners . A fellow FRC member had a source for 5000' rolls 
of 1/4  Strand and 502 insulators
  and these  GUY grips  that are used in the Cable industry...  from pole to 
pole to support the cable.
   
  These  grips had the 4 twisted wire with yellow tag
   
  I had access to the Quality  Control Lab @ the Mack  Trucks test lab,
   
  We first tested  Rohn 1/4 EHS.   to facilitate the pull  I installed 3  Press 
furls on each end
   
   all test were repeated 2X
   
  The EHS began to stretch twist and fracture @  9K  and fail @ 10.2K  lb pull
   
  Rohn PLP BIG GRIP (5) strand , with a length of  1/4 EHS   and the same furl 
at the end
  never failed with the EHS stretching and failing at  11 + 
K lb pull
   
  now the  Shorter 4 strand twist yellow tagged  with the same length EHS ( 16" 
exposed if my memory serves me )
   This to never Failed  and the  1/4  EHS  both times 
failing .
   
  We painted layout dye on the 1/4 ehs/grip ends  looking for pull out   NONE 
was found on either  DEAD END
   
   
  the guy grip loop end was around a solid 1 .250  rod to mimic a 502 or Rohn 
tower leg  or HD thimble.
   
  I tried Thimbles  but the press destroyed them in the  clamp down securing  
phase . 
   
  Conclusion  4 towers 180 plus guy grips   All 4 strand DEAD End type
   
  and 25 years and  all A - OK... I even caught a lower level guy on my ROPS 
bolt on my BIG tractor
   
  pulling so hard till I got to stop it Ripped the joint open and bent it 70 
degree on ROHN 25  
   
  AND DID NOT FAIL. It's length was 73' with two 502's attached directly to 
the tower leg and three way equalizer plate.
   
  MY  .02


   

  > From: k...@jeremy.mv.com
  > To: w...@w8ji.com; topband@contesting.com
  > Date: Fri, 5 Sep 2014 10:46:37 -0400
  > Subject: Re: Topband: WTB: Guy wire stuff
  > 
  > > Preform comes from the name of a major grip manufacturer, not from "tower 
  > > apes".
  > > http://www.preformed.com/
  > 
  > ** Which has never been denied by anyone in this discussion. OTOH linemen 
  > and other strand installers use it as a general description thus my tower 
  > ape terminology.
  > 
  > >
  > >
  > > Dead end is the termination style of grip.
  > > 
http://www.preformed.com/index.php?option=com_phocadownload&view=category&id=15&Itemid=145
  > >
  > 
  > ** Also previously discussed
  > 
  > >
  > > The normal "Guy Grip dead end" is typically used on any shorter length 
guy 
  > > line that does not have rotational or twisting forces, and they are 
  > > normally are rated at 100% of stand breaking strength (but you should 
  > > check the catalog specs because some are less).
  > 
  > ** As are the Big Grips rated at strand strength.
  > 
  > 
  > >
  > > The "Big Grip dead end" is the Prefomed Line Products name for the longer 
  > > grips, and are better for longer guy runs that might twist.
  > >
  > > PLP manufactures custom grips that are not cataloged. PLP would probably 
  > > be a better place for application advice than Ham tower parts vendors 
(who 
  > > sell some pretty sketchy stuff at times) or Ham reflectors. :)
  > 
  > 
  > ** PLP marketing is aimed at commercial and industrial applications and not 
  > hobbiests. Their idea of a radio tower starts where most ham versions let 
  > off.
  > 
  > 
  > 
  > > Every tower failure I have seen has come from incorrectly installed guy 
  > > strand, saddle clamps, or anchors. I've seen towers where people splice 
  > > guy lines with dead ends looped through dead ends!
  > 
  > 
  > ** Ive even seen some with RatShak guy wire which is maybe 1/8. Ive never 
  > used an inline splice either.
  > 
  > 
  > It's common to see someone
  > > worry enough to buy extra long grips (which doesn't do mu

Re: Topband: WTB: Guy wire stuff

2014-09-05 Thread Tom W8JI

Preform comes from the name of a major grip manufacturer, not from "tower 
apes".

http://www.preformed.com/


Dead end is the termination style of grip.
http://www.preformed.com/index.php?option=com_phocadownload&view=category&id=15&Itemid=145


The normal "Guy Grip dead end" is typically used on any shorter length guy 
line that does not have rotational or twisting forces, and they are normally 
are rated at 100% of stand breaking strength (but you should check the 
catalog specs because some are less).


The "Big Grip dead end" is the Prefomed Line Products name for the longer 
grips, and are better for longer guy runs that might twist.


PLP manufactures custom grips that are not cataloged. PLP would probably be 
a better place for application advice than Ham tower parts vendors (who sell 
some pretty sketchy stuff at times) or Ham reflectors.  :)


Every tower failure I have seen has come from incorrectly installed guy 
strand, saddle clamps, or anchors. I've seen towers where people splice guy 
lines with dead ends looped through dead ends! It's common to see someone 
worry enough to buy extra long grips (which doesn't do much for strength), 
and then not worry about radius inside the loop (which just kills the 
strength).



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Re: Topband: Bias Tee Measurements (Test Data)

2014-08-24 Thread Tom W8JI


Tom, you said "Any test is meaningless", and I don't understand where you
are coming from on that statement.  If you look at my test, I tested with
and without the bias Tee, and I tested with a well regulated bench top
linear power supply, and the results are similar so I don't see how you 
can

say you can't do that.  I then went and tested with a wall wart power
supply that produced 1.5 volts peak to peak ripple when under my 100 ohm
load on the Bias Tee DC port, and it did indeed produce noisy data as you
said would happen.  I believe my test shows that you can indeed make valid
measurements as long as you are using a well regulated supply.


I understood your test to be an indictment of using an unregulated supply, 
and that a well regulated supply cures issues. Of course what you intended 
to convey and what I thought you intended to convey might be two different 
things. If you only meant the filtered dc (unrelated to regulation or lack 
of regulation) allowed a reading in that case, I agree. It allows a reading 
in that case, BUT it is still dangerous to use a low voltage diode test 
device on that line to test things.


Because it can damage test equipment, I do not think it is a valid public 
test protocol for the general population.


The issue is not regulation. The issue is noise or ripple making it into the 
analyzer port. We can run well regulated dc with ripple, or even unfiltered 
unregulated dc into the line and just clean it up at the relay end so the 
relay does not chatter, and get a valid dc test as long as test equipment is 
not sensitive to low frequency noise.


We could never test ac, irrespective of filtering, regulation, or waveform, 
without skewing measurements. This means testing a four-way system with a 
bias T and ac, or rippled + or - dc, or with cable ground loop ac voltage 
offsets on the shield, can result in false readings. It won't affect the 
receiver at all, but we might think the system has a problem or damage our 
test gear.


The best way to improve the test method and increase reliability is to make 
the measurement device insensitive to offset on the output. It is better to 
remove ground loop low frequency bias or coupling through the capacitor by 
making it a highpass filter for low frequencies, although I probably still 
would not switch the relays with my test equipment connected unless I 
confirmed no transients first. :-)


The problem actually comes from the reactance of the series coupling 
capacitor and the sensitivity of many cheap measuring devices to out of band 
voltages. A solution that reduces low frequency offset from external ground 
loops and allows ac or unfiltered dc operation, is adding a shunting choke 
on the RX port.


So to clarify, I am saying:

1.)  the problem is not regulation, it is noise or ripple
2.) a filtered or regulated supply does not solve the ac mode test issue
3.) switching can result in a high voltage transient that can damage test 
gear
4.) low frequency ground loops might still inject ripple on long cable runs, 
or with poor shield connections

5.) regulation will still not allow an ac switch test

There is a second caveat I have about switching high impedance lines. We 
have to be very careful about relay contact and wiring capacitance. Just 10 
pF of contact capacitance is 8k ohms on 160 meters. We only have a coupled 
load to leakage path ratio of 10 times if we switch an 800 ohm line. That 
same leakage path to load becomes a 100 ratio if we use a transformer to 80 
ohms at the switch point.


Now I absolutely understand we will see an empirical "good F/B ratio" with 
some pretty dismal relay isolation, and of course it will not show as an SWR 
issue at all. I'm not disputing switching high Z lines will still make many 
people happy. When I build a system, I probably look at it differently. If I 
could have 15-20 dB of relay isolation when switching or 30-60 dB of relay 
isolation, and the difference only costs a couple dollars, I'd probably give 
up a cheeseburger and buy the piece of mind from switching low impedance 
points. If the transformers were $25 dollars each, I might not do that. My 
cheapness might take over. :-)


Simplicity is a wonderful thing as long as the saving a few pennies does not 
cost us dollars of joy over time.  When all the little mistakes we don't 
notice are added, we might be worse off than we assume. I'm simply offering 
a more reliable or accurate way to do things.


73 Tom 


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Re: Topband: Bias Tee Measurements (Test Data)

2014-08-23 Thread Tom W8JI

We cannot test impedance that way with a DC coupled impedance meter and get 
good data with any noise in the supply. Any test is meaningless. The .1 
capacitor will just couple any distortion or ripple in the AC to the 
analyzer, where it would show as jitter or false readings.


It would be a valid test if a moderately low resistance 200-500 uH RF choke 
shunted the analyzer (receiver) port.




- Original Message - 
From: "Don Kirk" 

To: "topband" 
Sent: Saturday, August 23, 2014 10:48 PM
Subject: Topband: Bias Tee Measurements (Test Data)



Late last year Pete (N4ZR) reported problems with his home brew Bias Tee
that included radical shifts in measured impedance when DC voltage was
applied to his Bias Tee.  Today I decided to make impedance measurements 
on

a simple Bias Tee circuit I recently proposed for Dwight (NS9I) who was
looking for a method of switching pennants via the feedline.

I was not able to duplicate the problems that Pete reported, but I did
notice unstable (noisy) impedance measurements when using a DC power 
supply

on the Bias Tee that had a lot of ripple when under load, and below is my
test data.  My proposed Bias Tee schematic for NS9I is on my Pennant
website at http://sites.google.com/site/pennantflagantennas/

--
*Test Data Using Resistor as the RF load *
66 foot of RG58U coax (measured Zo = 56 ohms)
Test Frequency = 4.545 Mhz (frequency where the coax was an electrical 1/2
wavelength)
RF Load = 50 ohm resistor

No Bias Tee (Bias Tee bypassed) :
R = 49, X = 0

Bias Tee (with 100 ohm 10 watt resistor connected to the Bias Tee DC 
output
port = 120mA load when 12 volts is applied), and well regulated DC supply 
:

0 Vdc R = 51, X = 0
+12 Vdc R = 51, X =0
-12 Vdc R = 51, X = 0

Note : when using a DC supply that had 1.5 volts peak to peak ripple the
measured R was jumping around between 46 and 53 ohms
-

*Test Data Using Transformer with the RF resistive load *66 foot of RG58U
coax (measured Zo = 56 ohms)
Test Frequency = 4.545 Mhz (frequency where the coax was an electrical 1/2
wavelength)
RF Load : Transformer BN-73-202 Binocular core (Primary = 3 turns,
Secondary = 12 turns) with 1K resistor connected to secondary

Bias Tee (with 100 ohm 10 watt resistor connected to the Bias Tee DC 
output
port = 120mA load when 12 volts is applied), and well regulated DC supply 
:

0 Vdc R = 55, X = 0
+12 Vdc R = 55, X =0
-12 Vdc R = 55, X = 0

Note : when using a DC supply that had 1.5 volts peak to peak ripple the
measured R was jumping around between 49 and 58 ohms

Note : For the above tests I was using an antenna analyzer that I designed
and built last year, and the detector is based on the VK5JST antenna
analyzer.  The diodes used in the detector are germanium which have a high
enough voltage rating to allow impedance measurements on the Bias Tee
without the concern that W8JI had about detector diodes being damaged due
to high voltage exposure when measuring Bias Tees.

I repeated the 1st test shown above (Resistor as the RF load) between 1.4
and 12.5 Mhz and the results were similar (no change in measured impedance
between 0, -12, and + 12 Vdc applied Bias Tee voltage).
-

*Conclusion*
The Bias Tee (concept based on an AD5X Bias Tee design) measured impedance
does not change between an applied voltage of 0 and +/-12 volts DC when
using a well regulated supply (based on the 120 mA load used in my test)
when tested between 1.4 and 12.5 Mhz.

Just FYI,
Don (wd8dsb)
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Re: Topband: Skimmer calibration

2014-08-20 Thread Tom W8JI


I said:

That just isn't factual at all. Radials under the vertical antenna have 
virtually no effect on wave angle unless they are sparse and grossly 
unbalanced, allowing them to radiate like a low horizontal antenna.


Radials change the efficiency, not the pattern, unless the radials 
radiate like a dipole.


73 Tom



Note that I didnt say anything about changing the pattern, just the energy 
included at low angles and where the efficiency starts at the base and at 
the often poorly understood Fresnel Zone if you really want more power in 
those low angles and not heating worms or sand granules.


That, by definition, is a pattern change.

You said it improves groundwave. What you think happen just does not happen.

It improves efficiency. It does not change elevation pattern, it does not 
change Fresnel zone losses significantly. It does not improve groundwave any 
significant amount more than it changes sky wave.


This is because the "often poorly understood" Fresnel zone extends far 
beyond practical radial field area, and virtually all of the ground wave 
attenuation from soil losses is miles from the antenna over the entire long 
length of a path. It is not localized loss.


73 Tom


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Re: Topband: Skimmer calibration

BC antennas have the elaborate radial system in order to get that 
groundwave while the typical on ground ham vertical loses a lot of the 
0-10 degree (or more) radiation. Go to the beach to get it back.or go 
with elevated radials.





That just isn't factual at all. Radials under the vertical antenna have 
virtually no effect on wave angle unless they are sparse and grossly 
unbalanced, allowing them to radiate like a low horizontal antenna.


Radials change the efficiency, not the pattern, unless the radials radiate 
like a dipole.


73 Tom


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Re: Topband: Switching Pennants


I would not switch high impedance lines without very special precautions.

I really do not think it is worth the small parts savings. 



- Original Message - 
From: "DGB" 

To: 
Sent: Tuesday, August 19, 2014 4:38 PM
Subject: Topband: Switching Pennants



I am wanting a simple way of switching 3 or 4 pennants. Anyone done this?

Quote From K6SEE ... All four Pennants would be installed with their 
points all adjacent to each other.  Only one feedline would be necessary 
and only one
transformer would be necessary, with the high impedance winding of the 
transformer being switched to the feedpoint of the Pennant in the desired

direction ... 73, de Earl, K6SE

73 Dwight NS9I
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Re: Topband: Skimmer calibration


Do we really care that skimmers aren't hooked up to antennas with
pattern and gain?  One of the things in using VOACAP is knowing the
pattern of the RX antenna as well as TX. Omni pattern at RX removes RX
antenna bias.  Why shouldn't we specifically use omni on RX, so that
any enhancement is from the sender or the propagation/environment?



If I wanted to know what antenna was better, I would use a short vertical or 
vertically polarized antenna for most applications.


Ideally, you want a broad elevation pattern with no nulls. A 2 foot vertical 
has about the same pattern as a 130 ft vert for elevation on 160, so the 
only issue is sensitivity falling into RX internal noise.


I think people live on the false notion that verticals have a null at near 
zero, which patterns on Ham models will show, but that is a program display 
shortfall causing that error. If they really were zero, all broadcast 
stations would be dark for groundwave. :)





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Re: Topband: New 3 el 160m yagi at 7J4AAL


On Tue,8/19/2014 10:03 AM, Doug Renwick wrote:
I thought the consensus now is yagi antennas on 160 don't perform well 
(i.e. OH8X) when compared to vertical arrays.


That is STRONGLY dependent on the height of the Yagi and soil conductivity 
around the vertical antenna.  A horizontal antenna lower than about a half 
wave is a "low" antenna, so the vertical pattern is compromised. On the 
other hand, verticals are strongly affected by soil conductivity -- as 
much as 6 dB between very poor and very good -- while horizontal antennas 
are not.  This Yagi is at almost 3/8 wavelength on 160, pretty good, but 
still not great. I'd guess the gain to be no better than 5 dB over a 
dipole at the same height.


It also depends on the earth's magnetic field and how it affects the 
ionosphere, apparently.


From my location, at one point in time, I had phased full-size wire dipoles 
(droopy Inverted Vee dipoles) at about 300 feet apex height, with the leg 
ends at least around 250 feet. It was averaged over thousands of reports a 
little less than the optimized phase and current (NOT a hybrid) four square 
I have. It never was significantly stronger.


But that is just here at this location.

When I was young and in Ohio I had a dipole on an FM tower at 330 feet over 
a black sandy loam soil marsh. I remembered how well it worked. That was why 
I installed a 300 ft tower here. Once I installed the 300 ft tower, which 
was on an insulator, my memory cleared and I got real. I remembered the few 
times I A-B tested a 130 ft vertical at my house a few miles away and 
couldn't see much actual difference.


80 meters is a different story with horizontal polarization.

It's like those fast muscle cars we all had in the 1960's that we remember 
as being fast and wonderful, but were actually slower, handled much worse, 
were far less comfortable and reliable, and had terrible fuel mileage than 
our modern showroom cars. 


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Re: Topband: Modeling the proverbial "vertical on a beach"

Definitely, as I'd mentioned, less site-to-site variability would be shown 
with a full-size efficient transmitting type antenna, whether a vertical 
over a good ground system or a high (>150 ft. elevation) horizontal dipole 
/ yagi.


Smaller receiving loops and active whips exhibit the greatest influence 
due to surrounding ground conductivity and elevation profiles.  This is 
particularly the case on groundwave or very low angle skip.  High angle 
skip is largely unaffected by the nature of the surrounding landscape; 
certainly by the time you get to Near Vertical Incidence, that can work 
even if you are surrounded by tall buildings or mountains.




Why would it matter?

The receiving antenna does not matter, provided it responds to the wave 
angle at the receive site. It doesn't matter if it is loop, a 10 foot 
vertical, or a 200 foot vertical so long as the antenna does not null the 
primary wave angle for the incoming signal. It does not matter if it is a 
large receiving array or a whip, provided each are not nulling the primary 
signal arrival.


When broadcast station are measured, the engineer walks around with a hand 
held loop. The loop is calibrated in volts. If someone changes TX antenna 
pattern or power or efficiency, it shows as exactly the same change no 
matter what the soil under the test meter. As a matter of fact, as long as 
you don't need to know absolute levels (which Hams virtually never need to 
know) the meter does not need to be calibrated to any voltage reference. 
You can throw a 20 dB pad in the system, and as long as the internal 
sensitivity and noise does not limit the reading, the change would still be 
linear.


The only critical thing is the transmitting reference signal we are 
comparing with, and filtering out QSB and selective fading with a lot of 
averaging. Any of us who grew up in the AM days are likely to remember all 
about frequency selective fading.  :)


73 Tom 


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Re: Topband: Skimmer calibration

2014-08-18 Thread Tom W8JI

Since no one likely knows the gain of a reference antenna within a dB or so, 
splitting hairs doesn't matter.


Ten dB would jump right out, while 3 dB might get lost in the QSB.

When I was comparing high dipoles to verticals on 160, I collected reports 
for about a year. It was thousands of reports.


I probably could have done it in a week or two with skimmer, but then I 
would have had to repeat it for seasonal changes. I'm sure a good test 
protocol using skimmer could be worked out.



- Original Message - 
From: "Jim Brown" 

To: 
Sent: Monday, August 18, 2014 12:47 PM
Subject: Re: Topband: Skimmer calibration



On Mon,8/18/2014 4:53 AM, Tom W8JI wrote:
A live comparison of S/N ratio or relative level over time is with very 
few exceptions an excellent comparative test. It is much more accurate 
than S meters or absolute levels without a comparison reference. As such, 
the RBN is a great tool for evaluating systems.


Yes. BUT -- my experience has been that I must average hundreds of data 
points to get meaningful data. The reasons are simple -- we must contend 
with QSB, and as Tom noted in another post, nulls in the patterns of 
antennas at both ends. A few years ago, I tried to compare two 160M 
antennas using JT65 and W6CQZ's JT65 RBN. On a good night, I would see 
reports from 3-4 stations east of the Mississippi. I alternated between 
the two antennas for hours, putting the reports in a spreadsheet, and 
studying the data. Modelling predicted differences of a few dB, and I 
never found that the data was good enough to confirm the models.  The 
antennas are passive arrays of fairly tall verticals of a quarter wave or 
less, so there are no vertical nulls in their pattern. I can clearly hear 
their directivity on RX, but their gain is what I was trying to confirm.


73, Jim K9YC


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Re: Topband: Skimmer calibration

2014-08-18 Thread Tom W8JI

This is why some time and multiple skimmers must be involved in the 
statisticsotherwise data doesn't mean much.


Without skimmer I never settled on antennas until many dozens of blind AB 
test reports. I think skimmer is a more accurate way, because the human at 
the RX end is out of the picture.





There's a lot of scatter in the dB measurements from skimmers. If I see
dozens of spots graphed on the reversebeacon "spots comparison tool" then 
I

can believe systemic differences like 3-5dB. But I could never draw that
conclusion over a single pair of spots.

Any given skimmer will spot a given station on a given frequency at most
once every ten minutes. But when the geographic density of skimmers is
large enough (e.g. East coast US or Western Europe) just raw quantities or
breadth of spots starts being more interesting than exact dB level. Even
with the paucity of skimmers on west coast of US, I can still see who has 
a

4-square for transmit and how they steer it during the contest.

Tim N3QE



On Mon, Aug 18, 2014 at 7:53 AM, Tom W8JI  wrote:




I am not a Skimmer expert, and am just asking. Question:  Are all the
Skimmers individually(and collectively) calibrated in concert? Can one 
rely
on them for comparing scientific data and conclusion to prove or 
ascertain

a point?Val>>>>

Val,

A live comparison of S/N ratio or relative level over time is with very
few exceptions an excellent comparative test. It is much more accurate 
than

S meters or absolute levels without a comparison reference. As such, the
RBN is a great tool for evaluating systems.

The problems are:

1.)  For determining small differences, less than around 5 dB, you have 
to

know the performance level of the reference antenna or station. (For that
reason, I use a simple dipole reference.)

2.) The reference and AUT (antenna under test) have to be reasonably 
close

together to eliminate propagation variances, but not so close as to
interact, and they have to be in the clear. For example, it would be
foolish for me to plant a dipole in the middle of a bunch of Yagi 
antennas

and call it a reference, or put the antenna being evaluated in an
obstructed area.

3.) On skywave, there has to be some time involved with readings averaged
over time. This is somewhat true if there is more than a few wavelengths
distance between antennas, and especially true (almost critical) when
comparing different polarization antennas.

4.) Ideally the reference and AUT should be the same polarization, unless
we simply want to know which is louder overall.

5.) Antennas have sweet and sour heights for a given set of conditions. 
We
have to be very careful of this. This is especially true when antennas 
are
more than a half wavelength high above ground, because the antenna 
pattern

will be a series of deep nulls that selectively "notch out" a given wave
angle.

The RBN is an excellent tool. It does not need to be calibrated in
absolute level, only in dB, and dB to noise is just fine provided the 
noise

level of the receive site is steady.

One thing I hope we all can do is stop acting so "American" (we are now
what, 30th or 40th in math and science?) and get back to constructive
exchanges of information. If we stop learning and just pick a position 
and
fight, which is our trend today, this becomes a useless hobby and there 
is

no reason to communicate.

73 Tom
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Topband: Skimmer calibration

2014-08-18 Thread Tom W8JI




I am not a Skimmer expert, and am just asking. Question:  Are all the 
Skimmers individually(and collectively) calibrated in concert? Can one rely 
on them for comparing scientific data and conclusion to prove or ascertain a 
point?Val>>>>


Val,

A live comparison of S/N ratio or relative level over time is with very few 
exceptions an excellent comparative test. It is much more accurate than S 
meters or absolute levels without a comparison reference. As such, the RBN 
is a great tool for evaluating systems.


The problems are:

1.)  For determining small differences, less than around 5 dB, you have to 
know the performance level of the reference antenna or station. (For that 
reason, I use a simple dipole reference.)


2.) The reference and AUT (antenna under test) have to be reasonably close 
together to eliminate propagation variances, but not so close as to 
interact, and they have to be in the clear. For example, it would be foolish 
for me to plant a dipole in the middle of a bunch of Yagi antennas and call 
it a reference, or put the antenna being evaluated in an obstructed area.


3.) On skywave, there has to be some time involved with readings averaged 
over time. This is somewhat true if there is more than a few wavelengths 
distance between antennas, and especially true (almost critical) when 
comparing different polarization antennas.


4.) Ideally the reference and AUT should be the same polarization, unless we 
simply want to know which is louder overall.


5.) Antennas have sweet and sour heights for a given set of conditions. We 
have to be very careful of this. This is especially true when antennas are 
more than a half wavelength high above ground, because the antenna pattern 
will be a series of deep nulls that selectively "notch out" a given wave 
angle.


The RBN is an excellent tool. It does not need to be calibrated in absolute 
level, only in dB, and dB to noise is just fine provided the noise level of 
the receive site is steady.


One thing I hope we all can do is stop acting so "American" (we are now 
what, 30th or 40th in math and science?) and get back to constructive 
exchanges of information. If we stop learning and just pick a position and 
fight, which is our trend today, this becomes a useless hobby and there is 
no reason to communicate.


73 Tom 


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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-15 Thread Tom W8JI

That makes no sense at all. What are you trying to say?

- Original Message - 
From: "Carl" 

To: "Tom W8JI" ; "'TopBand List'" 
Sent: Friday, August 15, 2014 12:39 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

A 3CX15000B7 or similar makes up for a lot of things and especially to 
those who always want to be on top in a pileup or contest.

Carl
KM1H

- Original Message - 
From: "Tom W8JI" 

To: "'TopBand List'" 
Sent: Friday, August 15, 2014 9:51 AM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

For receiving, an absence of noise sources in the path is all the 
difference in the world. As an example of this look at what N7JW and K7CA 
did from the Utah desert area. Utah desert is like the anti-saltwater, 
and they are located much further from Europe than the east coast with a 
worse polar area path, yet they had outstanding results. Saltwater has 
the same advantage, as do freshwater bodies, of a lack of noise sources 
in what might be a desired direction.

For efficiency (which only affects transmitting), the advantage is 
primarily concentrated at low angles and primarily affects vertically 
polarized systems. The question then becomes one of wave angle and 
polarization.

Then there is distance as a factor, and path loss related to the magnetic 
poles, which are factors.

A good station has a combination of everything going for it, but there is 
no magic and there certainly isn't any 10 dB or more involved just from 
being near saltwater. A few dB here and there from multiple factors are 
what make the difference. Move 25% or 50% closer, get rid of noise 
sources in the path, increase vertical antenna performance at low angles 
a few dB, and get away from going past the magnetic poles and it is a 
winner. It isn't from magic, and it isn't all from the presence of 
saltwater, and it is not 10-20 dB by any stretch of the imagination.

73 Tom
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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-15 Thread Tom W8JI



For receiving, an absence of noise sources in the path is all the difference 
in the world. As an example of this look at what N7JW and K7CA did from the 
Utah desert area. Utah desert is like the anti-saltwater, and they are 
located much further from Europe than the east coast with a worse polar area 
path, yet they had outstanding results. Saltwater has the same advantage, as 
do freshwater bodies, of a lack of noise sources in what might be a desired 
direction.


For efficiency (which only affects transmitting), the advantage is primarily 
concentrated at low angles and primarily affects vertically polarized 
systems. The question then becomes one of wave angle and polarization.


Then there is distance as a factor, and path loss related to the magnetic 
poles, which are factors.


A good station has a combination of everything going for it, but there is no 
magic and there certainly isn't any 10 dB or more involved just from being 
near saltwater. A few dB here and there from multiple factors are what make 
the difference. Move 25% or 50% closer, get rid of noise sources in the 
path, increase vertical antenna performance at low angles a few dB, and get 
away from going past the magnetic poles and it is a winner. It isn't from 
magic, and it isn't all from the presence of saltwater, and it is not 10-20 
dB by any stretch of the imagination.


73 Tom 


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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-15 Thread Tom W8JI


The signals showing the most change were not the loudest. They were
the ones on the edge of the developing band opening. The stronger or
peak signals from these stations would occur later as (presumably) the
angle of arrival moved up. The advantage to the water's edge I was
hearing would only last from first hearing to full band opening. To
the extent that the opening was very marginal, the advantage could
persist.



One of the big things in any experiment is to think about all the factors 
that can cause a feeling or impression, and just look at the meaningful 
numbers.


1.) If you had a non-linear effect based on loss it was probably the common 
effect of small changes in threshold signals being most noticeable. This 
effect is just a fact of life. We see it without realizing it. Linear loss, 
and we know the loss is linear with level, change weak signals exactly the 
same as strong signals. They change noise exactly the same as signals.


2.) If you were observing a wave angle effect, you would have had to sort 
the signals by wave angle. The irony of this is the most vocal advocates of 
high angle propagation, where salt water has no advantage (except a small 
one on bounce) over a localized very modest copper screen, are the same 
people who claim enhancement.


All of this is measureable if we do a correct and reasonable test. It is not 
measureable or observable with poor methods, or by human emotionometers.


It is, on the surface, illogical to claim weak signals are changed in a way 
that does not occur on stronger signals. Nowhere in anything except 
non-linear circuits will that occur.


When people come up with numbers or observations exceeding the change 
possible by moving an antenna from over soil to over an infinite copper 
sheet, or invoke some sort of non-linearity based on level, something is 
obviously wrong with the observation or reporting.


73 Tom 


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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-14 Thread Tom W8JI


I looked at comparative data from four or five contests.

I'm too far out of the path and in distance (approaching 1000 miles 
different) to compare, but I was still interested in how others in the NE 
compared.


If it was really 10-20 dB, shore locations would stand out like a sore thumb 
compared to inland locations. Everyone from around New England is about the 
same. Heck, K3LR is on the Ohio/PA border and does just as well or better 
than coastal stations in signal levels.


10 dB is completely undoable with antenna systems, once someone is at the 10 
dB threshold of gain over a dipole at optimal height (except on 160 where 
polarization is a player, and we have to compare vertical to vertical). 20 
dB would be beyond the world of magic.


Understand I'm not saying there isn't a difference. I'm just saying it isn't 
an exaggerated difference that jumps out in the ways we use our systems.


Watch skimmer yourself. It is entertaining to watch.

73 Tom







- Original Message - 
From: "Michael Tope" 

To: 
Sent: Thursday, August 14, 2014 5:03 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"



On 8/13/2014 6:28 PM, Tom W8JI wrote:




But skimmer, which displays a relative level, does not show the level 
difference.


Skimmer shows about the same peak levels, but the stations closer or over 
salt water paths (not localized salt water) have longer openings but no 
more level for peak level. Anyone can look at that.


K3LR is about as strong into Europe, when I look at skimmer levels, as 
someone on the coast.


The exceptions are people right next door to Europe (like VY1).


73 Tom


Tom,

How much skimmer data did you mine before establishing a firm conclusion 
that the advantages of saltwater proximity are exaggerated?


Myself, I think of how well AA7JV and HA7RY have done at various locations 
using antennas that were very close to or in some cases literally in the 
saltwater. The consistency of their topband signals compared to 
Dxpeditions who were confined to inland locations seems to point to a big 
advantage. I'll admit, however, that this hypotheses comes about from 
anecdotal observations filtered through a mental lens that is biased 
towards believing saltwater is a huge advantage.


I think using skimmer is an excellent approach to this question provided 
of course that you have mined enough data to filter out the statistical 
noise.


73, Mike W4EF...

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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-13 Thread Tom W8JI

One would think if there was a 10-20 db penalty, it would show on
skimmers
and that W2GD would be unbeatable being on the water. I'm sure I'm
missing

something. What is it I am missing?

A contest certainly is not only about transmit signal strength, nor is
the lowest angle propagation always the most productive. There is
always the 27 dB gain between the operator's ears (or lack of it) to
be reckoned with.

But skimmer, which displays a relative level, does not show the level
difference.

Skimmer shows about the same peak levels, but the stations closer or over
salt water paths (not localized salt water) have longer openings but no more
level for peak level. Anyone can look at that.

K3LR is about as strong into Europe, when I look at skimmer levels, as
someone on the coast.

The exceptions are people right next door to Europe (like VY1).

VOA relocated in NC to improve signals from the old New Jersey/New York
stations.

http://en.wikipedia.org/wiki/International_Broadcasting_Bureau_Greenville_Transmitting_Station

35.697429, -77.150056 is about 30 miles from Swan Bay, and maybe 60 from the
ocean.

https://www.google.com/maps/@36.1126131,-76.4678737,10z

Now understand I'm not saying salt water does not help groundwave
tremendously, but people inland needn't fear being competitive. I can't find
any supporting data for 10-20 dB, or longer propagation time, other than
being significantly closer to the target area or perhaps having saltwater
path at the first hop out.

It also can be quieter when directional antennas beam out over water, which
lacks urban noise.

If we compare K3LR's signal to someone from the black hole, when the path is
near the north magnetic pole (and distance is similar), there is a world of
difference. Not so between inland and the east coast at similar path angles
and distance, other than darkness times.

It would be interesting to see real data of the differences, because it is
tough to see on skimmer watching signal levels.

This should be an interesting thing to look at objectively and maturely.

73 Tom

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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-13 Thread Tom W8JI


this brings back a lot of memories..i arrived on rarotonga a week
after a French Dxpidition did, who was set up in the K2KW motel room with
vertical antennas on the beach just as you would imagine. the motel
management said she was sorry, and set me up in a cottage (from the same
motel) on the other side of the island for me and my venerable HW-16, now
connected to a 400 foot long wire to a 100(?) foot high palm tree. i was
across a road to the beach (75 feet from the shore?), but could on 160m
easily hear the USA 579 two hours before sunset


Receiving is virtually always a matter of signal-to-noise ratio in the space 
around the antenna. The only cases where more antenna efficiency helps is 
when the external signal **and external noise** is so weak it is near system 
internal noise.


High conductivity earth can actually hurt S/N ratio because it extends 
ground wave far more than it changes higher angle signals.


Transmitting is a different story, if lower angles are used. I doubt, 
however, it is ever close to 10-20 dB unless it is groundwave propagation. 
I'm sure people somewhere have actual numbers on that.


73 Tom 


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Re: Topband: Ferrites and verticals

2014-08-13 Thread Tom W8JI

The answer below by Sinisa is one of the best and most factual I have ever 
seen.


I would only add that when the coupling through air greatly exceeds the 
coupling through common mode, there is no reason to increase the choke 
impedance. Elevated radials are a different story, because common mode 
coupling to lossy ground increases losses.


I have many cases where just 20-50 ohms is more than enough, and in a very 
few others proper impedance is nearly impossible. In that case, changing 
cable lengths or modifying grounding corrects things.



The purpose of a choke is to prevent the coax shield
from becoming a part of your antenna.

Do you want to connect directly to your antenna
a long conductor with random length and position,
connected directly to your household appliances and
to other innumerable sources of noise?'

If not, place a "good enough choke" at antenna feed terminals.
Additional chokes may have to be placed elsewhere, but that's another 
story.


What constitues a "good enough choke" depends on circumstances.
In general, a choke with common mode impedance of at least 500 Ohm
is required for well behaved antennas such as symmetrical dipoles and 
beams.

Off-center fed antennas may require tens of kOhms.

A resonant vertical (not necessarily full size) with large full-size 
radials

has a very mild requirements on choke common mode impedance.
But an elevated "ground plane" antenna with 3 or 4 radials needs a very 
good choke, or several of them.
And a vertical having a few very short "counterpoises" needs an extremely 
good choke.
Such an antenna is essentially an off-center fed dipole, placed 
vertically.


So, one either studies in detail the electromagnetics of his own antenna,
and determines the necessary common mode impedance of the choke by 
calculation,

or just puts in a very good choke (with measured common mode impedance)
on the operating frequency, and hopes for the best.

A choke with unknown common mode impedance
can be likened to a screw of unknown diameter and pitch.
It may fit your purpose, but it also may completely fail to do so.


73,

Sinisa  YT1NT, VE3EA
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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-12 Thread Tom W8JI

- Original Message - 
From: "Yuri Blanarovich" 

To: 
Sent: Tuesday, August 12, 2014 4:50 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

Oh, here comes the "guru" again. :-)

Is that immature stuff really necessary?

Unnecessary debate? We are talking about experiences and RESULTS of 
comparing normal in land "ground" effect vs. salt water beach or marshes. 
We are commenting on the benefit of immediate proximity of salt water to 
antenna performance, especially on low angles.
K3BU and others found out that it is not "feeling," but S-meter readings 
in order of 10 - 20 dB (RX and TX!) in favor of salty beach. It is like 
driving inside into the amplifier

Perhaps you can explain why VOA and others willingly gave up that 10-20 dB, 
and how K3LR and W3LPL do so well inland, when they pay a 10-20 dB penalty 
for communications?

One would think if there was a 10-20 db penalty, it would show on skimmers 
and that W2GD would be unbeatable being on the water. I'm sure I'm missing 
something. What is it I am missing?

Thanks, Tom

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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-12 Thread Tom W8JI

By the way, my intention is not to make anyone feel bad, but to just to 
remind people that an impression or feeling is not confirmation. Impressions 
really get us off track, and lead to unnecessary debates and arguments.




- Original Message - 
From: "Tom W8JI" 

To: 
Sent: Tuesday, August 12, 2014 11:01 AM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


Just to set the record straight, I have no doubt saltwater helps 
propagation at most angles.


I probably did not make my point very well. My point is, with no 
comparison, an "impression" or "feeling" is not convincing data. It 
doesn't mean a thing.


I think this is a pretty simple concept. Not having proper comparative 
data is what allows all sorts of misplaced voodoo nonsense, like 360 
radials is worth 6 dB.


There is a huge  difference between the validity of an A-B comparison and 
running away with a feeling.





- Original Message - 
From: "Carl" 

To: "Yuri Blanarovich" ; 
Sent: Monday, August 11, 2014 9:51 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


There have been reports of verticals and salt water almost as long as 
there has been radio. It helps horizontal antennas also.


Ive operated for enough years aboard USN ships to know it is often a band 
opener and have to laugh at a couple of petty comments. The difference 
between operating shipboard and MARS/ham club stations was often a couple 
of hours and even with big yagis there was no comparison. Go back to the 
ship tied up at the pier or at anchor and the band was wide open again 
and again, and again.


After awhile you learn to ignore the nattering nabobs of negativism.

Carl
KM1H



- Original Message - 
From: "Yuri Blanarovich" 

To: 
Sent: Monday, August 11, 2014 9:30 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


One pony needs to get into one drag radio car and drive around the ocean 
front, over the bridges, back over the land and watch the S-meter and 
listen to the bands. Observant would see 10 - 20 dB difference in signal 
levels in "lousy" mobile, especially on low angle propagation.


Examples: Driving around Sydney, NS and listening to Disney 1670 AM in 
NJ - no signals over land, full quieting solid signal while driving on 
bridge over salt water.
While contesting as N2EE from Cape Hatteras, NC on 10m in contest, was 
told by ZS6EZ to be the first NA he heard, with vertical on the beach.

Results of "Team Vertical" speak for themselves.
Some of us do know. The reverse beacons testing can verify or legitimize 
modeling program's "calculated guessing".


Yuri, K3BU.us



On Sun, Aug 10, 2014 at 11:02 PM, Tom W8JI wrote:

> My point is if no one else is on, we really don't how other signals
would be. It's like a drag race with just one car, or a pony show with 
one horse.



- Original Message - From: "Hardy Landskov" To: "Tom W8JI" ; 
"TopBand List" Sent: Sunday, August 10, 2014 9:08 PM

Subject: Re: Topband: Modeling the proverbial "vertical on a beach"



Tom,
I was totallly not expecting any station from that direction, just 
thought I'd work a few locals with high incident angles before Sunset 
here. Then I heard the 6Y2 guys and it was amazing. He was the only 
station--no KV4FZ, NP4A, etc and certainly no EU at our time. Made me 
a believer in beach verticals.

73 N7RT

- Original Message - From: "Tom W8JI" To: "TopBand List" Sent: 
Sunday, August 10, 2014 5:20 PM

Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


How was his signal compared to someone from a similar heading and 
distance at the same time who was not on the beach?



- Original Message - From: "Hardy Landskov" To: "Guy Olinger 
K2AV" ; "Richard Fry"

Cc: "TopBand List" Sent: Sunday, August 10, 2014 7:35 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"



Just an observation to all:
When Tom, N6BT went to Jaimaca and operated 6Y2J (I think was the 
call) with verticals on the beach I was blown away. I heard them 2 
hours before Sunset here on 160nuff said. The proof is in the 
pudding.

73 N7RT

- Original Message - From: "Guy Olinger K2AV" To: "Richard 
Fry" Cc: "TopBand List" Sent: Saturday, August 09, 2014 8:35 PM

Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


Just to mention that the prior opinion is controversial and not 
universally
agreed upon. Nor to date has anyone surfaced with actual 
measurements made
at the distances (25 to 50 km) and with span of altitudes (0 to 10 
km) to

either prove or disprove either side.

It remains unproven modelling from NEC at those distances either

Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-12 Thread Tom W8JI

Just to set the record straight, I have no doubt saltwater helps propagation 
at most angles.


I probably did not make my point very well. My point is, with no comparison, 
an "impression" or "feeling" is not convincing data. It doesn't mean a 
thing.


I think this is a pretty simple concept. Not having proper comparative data 
is what allows all sorts of misplaced voodoo nonsense, like 360 radials is 
worth 6 dB.


There is a huge  difference between the validity of an A-B comparison and 
running away with a feeling.





- Original Message - 
From: "Carl" 

To: "Yuri Blanarovich" ; 
Sent: Monday, August 11, 2014 9:51 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


There have been reports of verticals and salt water almost as long as 
there has been radio. It helps horizontal antennas also.


Ive operated for enough years aboard USN ships to know it is often a band 
opener and have to laugh at a couple of petty comments. The difference 
between operating shipboard and MARS/ham club stations was often a couple 
of hours and even with big yagis there was no comparison. Go back to the 
ship tied up at the pier or at anchor and the band was wide open again and 
again, and again.


After awhile you learn to ignore the nattering nabobs of negativism.

Carl
KM1H



- Original Message - 
From: "Yuri Blanarovich" 

To: 
Sent: Monday, August 11, 2014 9:30 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


One pony needs to get into one drag radio car and drive around the ocean 
front, over the bridges, back over the land and watch the S-meter and 
listen to the bands. Observant would see 10 - 20 dB difference in signal 
levels in "lousy" mobile, especially on low angle propagation.


Examples: Driving around Sydney, NS and listening to Disney 1670 AM in 
NJ - no signals over land, full quieting solid signal while driving on 
bridge over salt water.
While contesting as N2EE from Cape Hatteras, NC on 10m in contest, was 
told by ZS6EZ to be the first NA he heard, with vertical on the beach.

Results of "Team Vertical" speak for themselves.
Some of us do know. The reverse beacons testing can verify or legitimize 
modeling program's "calculated guessing".


Yuri, K3BU.us



On Sun, Aug 10, 2014 at 11:02 PM, Tom W8JI wrote:

> My point is if no one else is on, we really don't how other signals
would be. It's like a drag race with just one car, or a pony show with 
one horse.



- Original Message - From: "Hardy Landskov" To: "Tom W8JI" ; 
"TopBand List" Sent: Sunday, August 10, 2014 9:08 PM

Subject: Re: Topband: Modeling the proverbial "vertical on a beach"



Tom,
I was totallly not expecting any station from that direction, just 
thought I'd work a few locals with high incident angles before Sunset 
here. Then I heard the 6Y2 guys and it was amazing. He was the only 
station--no KV4FZ, NP4A, etc and certainly no EU at our time. Made me a 
believer in beach verticals.

73 N7RT

- Original Message - From: "Tom W8JI" To: "TopBand List" Sent: 
Sunday, August 10, 2014 5:20 PM

Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


How was his signal compared to someone from a similar heading and 
distance at the same time who was not on the beach?



- Original Message - From: "Hardy Landskov" To: "Guy Olinger 
K2AV" ; "Richard Fry"

Cc: "TopBand List" Sent: Sunday, August 10, 2014 7:35 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"



Just an observation to all:
When Tom, N6BT went to Jaimaca and operated 6Y2J (I think was the 
call) with verticals on the beach I was blown away. I heard them 2 
hours before Sunset here on 160nuff said. The proof is in the 
pudding.

73 N7RT

- Original Message - From: "Guy Olinger K2AV" To: "Richard 
Fry" Cc: "TopBand List" Sent: Saturday, August 09, 2014 8:35 PM

Subject: Re: Topband: Modeling the proverbial "vertical on a beach"


Just to mention that the prior opinion is controversial and not 
universally
agreed upon. Nor to date has anyone surfaced with actual 
measurements made
at the distances (25 to 50 km) and with span of altitudes (0 to 10 
km) to

either prove or disprove either side.

It remains unproven modelling from NEC at those distances either 
way. This

situation may, alas, persist this way, because the precise subject
resolution appears to be without benefit to any commercial interest 
and
therefore without funds to pay for some pretty expensive 
experimenting

involving precision measurements from aircraft.

Additionally, there is considerable suspicion that moving from LF to 
MF in
this general subject involves a ground modal change of some so

Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-10 Thread Tom W8JI

My point is if no one else is on, we really don't how other signals would 
be. It's like a drag race with just one car, or a pony show with one horse.

- Original Message - 
From: "Hardy Landskov" 

To: "Tom W8JI" ; "TopBand List" 
Sent: Sunday, August 10, 2014 9:08 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

Tom,
I was totallly not expecting any station from that direction, just thought 
I'd work a few locals with high incident angles before Sunset here. Then I 
heard the 6Y2 guys and it was amazing. He was the only station--no KV4FZ, 
NP4A, etc and certainly no EU at our time. Made me a believer in beach 
verticals.

73 N7RT

- Original Message - 
From: "Tom W8JI" 

To: "TopBand List" 
Sent: Sunday, August 10, 2014 5:20 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

How was his signal compared to someone from a similar heading and 
distance at the same time who was not on the beach?

- Original Message - 
From: "Hardy Landskov" 
To: "Guy Olinger K2AV" ; "Richard Fry" 

Cc: "TopBand List" 
Sent: Sunday, August 10, 2014 7:35 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

Just an observation to all:
When Tom, N6BT went to Jaimaca and operated 6Y2J (I think was the call) 
with verticals on the beach I was blown away. I heard them 2 hours 
before Sunset here on 160nuff said. The proof is in the pudding.

73 N7RT

- Original Message - 
From: "Guy Olinger K2AV" 

To: "Richard Fry" 
Cc: "TopBand List" 
Sent: Saturday, August 09, 2014 8:35 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

Just to mention that the prior opinion is controversial and not 
universally
agreed upon. Nor to date has anyone surfaced with actual measurements 
made
at the distances (25 to 50 km) and with span of altitudes (0 to 10 km) 
to

either prove or disprove either side.

It remains unproven modelling from NEC at those distances either way. 
This

situation may, alas, persist this way, because the precise subject
resolution appears to be without benefit to any commercial interest and
therefore without funds to pay for some pretty expensive experimenting
involving precision measurements from aircraft.

Additionally, there is considerable suspicion that moving from LF to MF 
in
this general subject involves a ground modal change of some sort that 
would

render 50x10 km measurments at 0.5 or 1 MHz unlike those at 2 MHz,
rendering commercial measurements at low and possibly high BC of no 
value

for extrapolation to ham use.

Arguments on both sides remain basically intuitive. I have "reasonable"
arguments to BOTH concur with Richard AND to not. NEC near field
calculations over sea water at 50 km follow Richard's assertions, and 
the
same over "average" ground does not. The model clearly thinks that 50 
km

over most types of ground slowly dissipates low angles resulting in the
controversial "notch" in low angle elevation patterns.

So NEC based modelling cannot be used as a proof text to decide an 
argument

NEC has with itself.

73, Guy K2AV.

On Sat, Aug 9, 2014 at 7:23 PM, Richard Fry  wrote:

Just to note that the low-angle radiation produced by monopoles is not
accurately shown by a NEC model/study that does not include the 
surface
wave, regardless of whether one or two ground-plane media are 
specified in

the model.

Below is a link to a NEC study of the low-angle fields of a monopole
__including the surface wave__ for three values of earth conductivity
ranging from extremely good to very poor.

The curves there all show maximum relative field in the horizontal 
plane.

If the surface wave had not been included in these studies then all of
those fields would have a zero value in the horizontal plane, and 
reduced

fields at low angles just above the horizontal plane.

Reality is that radiation leaving the monopole at elevation angles of 
at
least 5 degrees decays at a 1/r rate.  Therefore that radiation is a 
space
wave which propagates in a ~ straight line to reach the ionosphere, 
where

(with suitable conditions) it can return to the earth as a skywave.

NEC analyses of a vertical monopole of 5/8-lambda and less, and not
including the fields of the NEC surface wave do not recognize the 
radiation
sector capable of producing the greatest single-hop skywave service 
range

that can be provided by that monopole.

http://s20.postimg.org/9xqgzu9d9/Monopole_Low_Angle_Radiation.jpg

R. Fry
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Re: Topband: Modeling the proverbial "vertical on a beach"

2014-08-10 Thread Tom W8JI

How was his signal compared to someone from a similar heading and distance 
at the same time who was not on the beach?

- Original Message - 
From: "Hardy Landskov" 

To: "Guy Olinger K2AV" ; "Richard Fry" 
Cc: "TopBand List" 
Sent: Sunday, August 10, 2014 7:35 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

Just an observation to all:
When Tom, N6BT went to Jaimaca and operated 6Y2J (I think was the call) 
with verticals on the beach I was blown away. I heard them 2 hours before 
Sunset here on 160nuff said. The proof is in the pudding.

73 N7RT

- Original Message - 
From: "Guy Olinger K2AV" 

To: "Richard Fry" 
Cc: "TopBand List" 
Sent: Saturday, August 09, 2014 8:35 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

Just to mention that the prior opinion is controversial and not 
universally
agreed upon. Nor to date has anyone surfaced with actual measurements 
made

at the distances (25 to 50 km) and with span of altitudes (0 to 10 km) to
either prove or disprove either side.

It remains unproven modelling from NEC at those distances either way. 
This

situation may, alas, persist this way, because the precise subject
resolution appears to be without benefit to any commercial interest and
therefore without funds to pay for some pretty expensive experimenting
involving precision measurements from aircraft.

Additionally, there is considerable suspicion that moving from LF to MF 
in
this general subject involves a ground modal change of some sort that 
would

render 50x10 km measurments at 0.5 or 1 MHz unlike those at 2 MHz,
rendering commercial measurements at low and possibly high BC of no value
for extrapolation to ham use.

Arguments on both sides remain basically intuitive. I have "reasonable"
arguments to BOTH concur with Richard AND to not. NEC near field
calculations over sea water at 50 km follow Richard's assertions, and the
same over "average" ground does not. The model clearly thinks that 50 km
over most types of ground slowly dissipates low angles resulting in the
controversial "notch" in low angle elevation patterns.

So NEC based modelling cannot be used as a proof text to decide an 
argument

NEC has with itself.

73, Guy K2AV.

On Sat, Aug 9, 2014 at 7:23 PM, Richard Fry  wrote:

Just to note that the low-angle radiation produced by monopoles is not
accurately shown by a NEC model/study that does not include the surface
wave, regardless of whether one or two ground-plane media are specified 
in

the model.

Below is a link to a NEC study of the low-angle fields of a monopole
__including the surface wave__ for three values of earth conductivity
ranging from extremely good to very poor.

The curves there all show maximum relative field in the horizontal 
plane.

If the surface wave had not been included in these studies then all of
those fields would have a zero value in the horizontal plane, and 
reduced

fields at low angles just above the horizontal plane.

Reality is that radiation leaving the monopole at elevation angles of at
least 5 degrees decays at a 1/r rate.  Therefore that radiation is a 
space
wave which propagates in a ~ straight line to reach the ionosphere, 
where

(with suitable conditions) it can return to the earth as a skywave.

NEC analyses of a vertical monopole of 5/8-lambda and less, and not
including the fields of the NEC surface wave do not recognize the 
radiation
sector capable of producing the greatest single-hop skywave service 
range

that can be provided by that monopole.

http://s20.postimg.org/9xqgzu9d9/Monopole_Low_Angle_Radiation.jpg

R. Fry
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Re: Topband: Ferrite Cores

2014-08-06 Thread Tom W8JI



In this discussion two different ferrite mixes are mentioned: #31 and #61.


From the descriptions of these on the Fair-Rite web page, it appears that 31 

would be more suitable for lower frequency applications. >>>>

Core selection can be fairly complex in transmitting systems. I've yet to 
see a case where one core mix is the be all end all for the range of things 
you run into in the field. Especially at high common mode impedances.


Receiving is a completely different story, because core stresses are always 
low.


73 Tom


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Re: Topband: Ferrite Cores

2014-08-05 Thread Tom W8JI

I have seen distributors of core mix cores many times over the years. This 
includes distributors on the "only approved list". This is why I always 
verify cores I use.

As for Fair Rite being the only legitimate source of part numbers, and 
everyone else being a criminal or trying to rip people off,
that's pretty silly. Every place I have worked since 1966 has used internal 
house numbers for parts. They didn't do that for any sinister criminal or 
immoral motives.

We need to lighten up a little. We sometimes sound like the grumpy 
opinionated old men we used to be scared of.

- Original Message - 
From: "Chuck Hutton" 

To: 
Sent: Tuesday, August 05, 2014 2:51 PM
Subject: Re: Topband: Ferrite Cores

Neither do I. It's quite common practice for distributors to have their 
own part numbers. Witness DigiKey - here is their ferrite page : 
http://www.digikey.com/product-search/en/inductors-coils-chokes/inductor-ferrite-cores/197937

Yes, Amidon has always seemed a bit high priced. However, I'd like to see 
some numbers rather than an opinionated post.

Chuck

From: bi...@waveform.net
To: j...@audiosystemsgroup.com; topband@contesting.com
Date: Tue, 5 Aug 2014 18:34:39 +
Subject: Re: Topband: Ferrite Cores

I don't think it was entirely a "scam" on the part of Amidon. When you 
think about it, FT-240-31 is easier to know "Ferrite, Toroid, 2.4" OD 
material #31" is a lot easier to remember than "2631803802" :-) Similar 
in concept to using channel numbers for TV instead of frequency 
assignments -- it makes it easier on the users/viewers.

  -Bill

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim
> Brown
> Sent: Tuesday, August 05, 2014 12:25 PM
> To: topband@contesting.com
> Subject: Re: Topband: Ferrite Cores
>
> On 8/5/2014 7:46 AM, Greg wrote:
> > The Mouser part picture does not look like a FT-240-31.
>
> The FT-series of part numbers are PHONY part numbers,  dreamed up many
> years ago by vendors who have sold them to hams for very high prices.
> The ACTUAL part number for a #31 2.4-in o.d. toroid, as defined by 
> Fair-Rite,
> the company that MAKES these parts, is 2631803802.  You will find that 
> part
> number in Appendix One of my tutorial.  Kits and Parts is one of those 
> high
> price vendors. Amidon may have been the originator of this scam. 
> Palomar

> and DXE are in that league as well. They created these phony baloney
> numbers so that you wouldn't find the part from a real industrial 
> vendor at

> one third the price.
>
> 73, Jim K9YC
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Re: Topband: Rig Comparisons

2014-08-03 Thread Tom W8JI


You¹ll final several references of ANAN users who have improved internal
transceiver shielding so that RF detection comes only from the sample port
and not internal leakage.  Otherwise, the ADP algorithm is trying to
simultaneously correct for non-linearity of two amplifiers (internal and
external) and not just one  < when only the external amp requires IMD
optimization.  >>>>>>>>>

I know Paul knows how it works, but the explanation was incorrect.

The bulk of distortion is almost always, with the exception of a few radios 
and amplifiers, from the transceiver. Most external amplifiers, with the 
exception of the common poorly designed tetrode systems and low voltage 
solid state amps, are significantly more linear than the exciter. A grounded 
grid triode amplifier using 8877 tubes, or even 811A tubes, is significantly 
cleaner than most radios (even when the amplifier is being hammered). The 
general exception are tetrodes with improper screen and bias regulation that 
lack the heavy negative feedback of grounded grid amps, or the rare radios 
with exceptional transmitter linearity.


Distortion correction *must* include the exciter, but it must be at the 
antenna port.


Unwanted coupling from the exciter does not cause the ADP system to correct 
the exciter. Unwanted coupling introduces a sample that is not 
representative of what is actually on the antenna port. This effect is 
commonly observed when we try to monitor our own transmitters with other 
receivers at the operating position. We often hear hum, noise, distortion, 
and artifacts that are not on the antenna line.


73 Tom 


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Re: Topband: Topband Digest, Vol 139, Issue 20

2014-08-01 Thread Tom W8JI


Poor guessing by Carl.

The control units are entirely different. One is just a switch, and the 
other is a microprocessor based system that has an omni function and a hot 
switch lockout for relay protection. It also has a relay clean function.


I this the original poster was asking about Array Solutions vs. DXE, and not 
Comtek.


The original poster might have been asking about the phasing box???

The control head is in the house on the desk. The phasing box is out at the 
antenna.  The various subparts of the system are very commonly called 
incorrect names, even by sales people. For example, the phasing box or 
outdoor unit is called a controller. The Q-sections that are nothing more 
than feedlines are called phasing lines. I never really am sure what part 
someone is asking about. :)


Another point about guessing...

The original error in hybrid 4 square design was from ignoring mutual 
coupling, and assuming element impedances were ~35 j0 for all four elements. 
The original thought was to transform the antennas to 100 ohms at the 
phasing box ports by using 1/4 wave 75-ohm Q sections. The 100 ohm ports 
were paralleled to get 50 ohms.


The problem with that idea is mutual coupling changes the antenna resonance 
and impedance. The antennas are not even close to the correct impedance, and 
are reactive with different signs when phased. The elements also require 
equal currents, not equal power. A hybrid tries to force equal power.


As far as I know, NONE of these units are true hybrids. This is 
because a true hybrid would have terrible F/B ratio and gain in this 
application. This is because:


1.) None of the elements or feedlines are 50 j0 when phased. They are all 
different impedances, except the center two elements. A hybrid ONLY provides 
the design phase when the termination is the design value, and that does not 
happen.


2.) None of the element groups require equal power. Equal power would result 
in a terrible F/B ratio.


The DXE outdoor unit, besides an omni function and sophisticated controller, 
is much better optimized for the impedances actually presented in the 
working system. Rather than accidentally working through a design shortfall 
in hybrid, like the original system many years ago was, it is planned for 
the loads presented by the system. Because none of these units are really 
hybrids (they would not work very well if they were), they are all 
different.


73 Tom



- Original Message - 
From: "Carl" 

To: "Mike Greenway" ; 
Sent: Thursday, July 31, 2014 8:00 PM
Subject: Re: Topband: Topband Digest, Vol 139, Issue 20



More like a Chevy vs one thats been dolled up a bit for more money (-:


- Original Message - 
From: "Mike Greenway" 

To: 
Sent: Thursday, July 31, 2014 2:25 PM
Subject: Re: Topband: Topband Digest, Vol 139, Issue 20


Hi Paul.. I have used two Comteks for over 20 years and they have never 
had a problem.  The DXE looks like a very nice unit and it appears to me 
the circuitry is about the same..  Either should work well I think... 
Ford versus Chevy...  73 Mike K4PI


From: topband-requ...@contesting.com
Sent: Thursday, July 31, 2014 12:00 PM
To: topband@contesting.com
Subject: Topband Digest, Vol 139, Issue 20

Send Topband mailing list submissions to
topband@contesting.com

To subscribe or unsubscribe via the World Wide Web, visit
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or, via email, send a message with subject or body 'help' to
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of Topband digest..."


Today's Topics:

  1. 4-square controllers (Paul Baldock)


--

Message: 1
Date: Wed, 30 Jul 2014 21:32:30 -0700
From: Paul Baldock 
To: 
Subject: Topband: 4-square controllers
Message-ID: <20140731043244.b6490ac9...@mx.contesting.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

Does anybody have an opinion on the DX Engineering verses the Array
Solutions 4 square controller?

- Paul  KW7Y



--

Subject: Digest Footer

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Re: Topband: Rig Question

2014-06-17 Thread Tom W8JI


One reason the K3 requires more care to set up is the ALC system.

Unless this has changed since I measured my K3,  the ALC system does not 
process anything like every other radio. The K3 ALC simply regulates gain to 
keep things linear. The unique ALC system is why the K3 does not have ALC 
overshoot. That deviation from normal is why the ALC and mic gain can't be 
used to "get louder" by using ALC to process the signal, or by shouting.


If you want punch, the only way to get it is with the processor (imagine 
that).


I could clearly see this when I measured average power compared to a 
constant level of peak power, and ran audio gain up. If I did that with a 
traditional ALC system, more gain would bring average closer to peak. When I 
did that on a K3, the effect was much less. The processor in the K3 changes 
the peak to average ratio, while the ALC mostly keeps you out of bandwidth 
or damage trouble.


On my other gear the ALC acts like a crude form of speech processing, 
complete with leading edge overshoot. Shouting makes it "process" or clip, 
like a processor.


73 Tom 


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Re: Topband: Rig Question

2014-06-16 Thread Tom W8JI


it sounded like the FT1000D...I then had my friend come in and close his
eyes and did the A/B comparison...and he couldn't tell the difference. 
So,

yes, the K3 will require some adjustment to be pleasing to any particular
ear but it's pretty easy to do if you want to.  (Now he doesn't like the 
K3
because it's too small.  I'll remind him of that when it comes time to 
send

his radio off to be repaired.)  73, Greg-N4CC



A few people like almost anything, a few people just don't like anything, 
and most people don't like a few things.


I prefer analog detection of weak signals in noise, but I can live with the 
K3 when it is adjusted to my liking. I don't like all the menus, and I 
especially don't like not being able to switch the preamp in and out on both 
channels with one button when in diversity.


As for transmit audio, there isn't a thing wrong with it. It can be adjusted 
to almost any taste, except those who specifically don't like the brand.


The K3 does some things virtually no other radio does properly concerning 
diversity and DX use, and it has excellent close spaced receiver 
performance, so for me there is really no other choice.


73 Tom 


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Re: Topband: 50 ohm direct burial coax cable

2014-06-13 Thread Tom W8JI

You bring up some good points. I got a couple of hundred feet of Flooded 
Commscope 75 ohm "RG-11" type at a good proce. I don't have the part 
number handy. I've been very happy with it at 100 watts. I'm thinking of 
running 500 watts. The center conductor is copper clad steel. I'm 
concerned about RF current losses because of the skin effect on 160 
meters. Does anyone have any experience with this type of CATV cable at 
high power?


A 1:5 maimatch may be an issue at the amplifier but I guess I can place a 
L matching circuit between the amp and coax to get the SWR down.




The worse case SWR of a 50 ohm system with 75 ohm cable isn't 1.5:1 when 
normalized to 50 ohms. It is 2.25:1.  1.5*1.5 = 2.25


A 50 ohm load with 1/4 wave of 75 ohm is 112.5 ohms, and that is 2.25:1. 
This is why the cable needs to be 1/2 wave long, so impedance is back around 
50 ohms. If you are unlucky and pick an odd 1/4 wave, and the load is 50, 
the input SWR is 2.25 in the lossless cable case at the radio.


Also, on longer cables, the low SWR bandwidth is narrower. This is because 
the cable is multiple 1/4 wave sections in series. If there are ten of the 
1/4 waves making up a 2.5 wave long cable, and if the frequency changes 5%, 
the total length error for all the sections is 50%. This narrows bandwidth, 
and reduces the depth of the magical low SWR point.


If the antenna is a bit higher that 50 ohms things get better, and if it is 
a a bit lower than 50 ohms things get worse fast.


With so much cheap 50 ohm cable pulled from cell sites around, it is far 
easier around here to get 50 ohm rather than 75.


Years ago I used 75 ohm because it was everywhere for free. Now I use 50 ohm 
heliax and don't regret it one bit. Small used lengths pulled from 2-way and 
cell sites are free or a very nominal cost


73 Tom 


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Re: Topband: Fsj4 series heliax around a rotor

2014-06-08 Thread Tom W8JI


That's what I was thinking all along. If you put enough large loops in it,
you could even get away with using 3/4" aluminum hardline. :-)  Of course,
that doesn't mean it should be done.


Even the CB operator down the road does this. He has regular 7/8th inch and, 
as far as I know, it has been like that at least ten years without an issue. 
That antenna flip flops in the wind all the time.


If a CB operator who has a ground system consisting of wires stuck in a jug 
of saltwater (he actually has that) can figure out to use a couple large 
circles in the heliax to his Joe Gun beam to stop breakage,  I expect Hams 
could figure it out.  :)



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Re: Topband: Feedpoint of short RX vertical

2014-06-08 Thread Tom W8JI

I think that idea of transformer balun or transformer unun isolation is 
generally a bad idea in a phased system, and not necessary in almost any 
system except very special cases.


I would generally just forget that system for a number of reasons.

Attenuation of common mode, and everyone forgets this, is attenuation is a 
function of shunt impedances (or common mode impedances) to the added series 
impedance. It is like the system forms an attenuator pad.


If you cannot accomplish adequate isolation with a simple choke of 
reasonable impedance, it is best to look at the system and correct it.


With a very short cable and reasonable "grounds" on each end, just a few 
dozen ohms of choke impedance makes a large change in attenuation. With very 
poor grounds, or the wrong cable lengths, almost no impedance will be 
adequate. People pick poor solutions because they fail to logically look at 
the system. Because they do not consider the system, the invent magic things 
to create unnecessary ridiculous impedances.


I would use a shield breaker for feeding an electrically very short dipole, 
because common mode impedance is always extremely high. It has no ground at 
all.  I would never use it on any type of Marconi (even with a poor a small 
element ground).


I might use it on a video system or a 60Hz - 20kHz system where a reasonable 
choke is difficult. Not on 2 MHz except very special cases. It is generally 
a misguided idea for most things at HF and higher.


<<
I made a braid breaker by using a binocular core 73-202 with 2 turns 
primairy and 2 turns on
secondary . The term braid breaker comes from John s latest edition of low 
band DX ing


I found that it is difficult to get signal levels identical on both elements 
when using it, so maybe better to use a good common mode choke at the 
feedpoint .>> 


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Re: Topband: Feedpoint of short RX vertical

2014-06-07 Thread Tom W8JI

When feeding short RX verticals with a coil and resistor in series, does it 
make sense to decouple the feedline

at the feedpoint with a braid breaker ?>>>

There is no universal answer.

The particular installation determines whether or not decoupling is 
necessary. Sometimes a ground rod alone is enough, and sometimes even 
several radials are not enough. Decoupling can help if:


1.) The ground system is marginal or poor. We do not want the coax feedline 
contributing signals or acting like part of the antenna.


2.) There is noise following the cable shields to the antenna

I do not decouple some of mine because the feedlines are all buried a foot 
deep for 160-170 feet to the center, I have several reasonably long radials 
on each element, and the antenna is far from any noise. Some of mine I 
decouple, because they are near the house and the cables are not deep 
buried.


73 Tom


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Re: Topband: 50 ohm direct burial coax cable

2014-06-04 Thread Tom WA2BCK


Mike,
I like LMR400-DB.  Not only is it direct burial but it is the lowest loss of 
the RG8 type cables.

73,
Tom WA2BCK

-Original Message- 
From: mstang...@comcast.net

Sent: Tuesday, June 03, 2014 10:10 AM
To: topband@contesting.com
Subject: Topband: 50 ohm direct burial coax cable

Does anyone know of a source for 50 ohm "RG-8" type direct burial coax able.

I can find many sources for CATV and Satellite 75 ohn cable but not 50 ohm.

Direct burial cable is coated with and anti-fungal compound. I''ve had 
success with 75 ohm cables for receiving and want to purchase 50 ohm direct 
burial for transmitter feeds.


Thanks,

Mike N2MS
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Re: Topband: Using 80m 1/4 vertical on 160

2014-06-03 Thread Tom W8JI

I am putting up a single DXE 80m 1/4 vertical.  I can put out the proper 
radials.  I will have to add some longer ones for 160.




That's a good vertical, and the 80M radials will probaby be adequate if you 
have enough of them.



Now to figure out switching in and out 160 and the matching.




That is always the difficult part. If you have a good ground system and high 
efficiency, voltage can get pretty high when on the higher band for a top 
wire, and the lower band for switching a coil. Many systems work at high 
power because of losses.


If you just want to run outside to change bands, it is easy. 


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Re: Topband: Fwd: cable clamps on old Phillystran

2014-05-30 Thread Tom W8JI

The only damage on my Yagi antennas from the ice storm we had (about an inch 
of radial ice) was to Philliystran struts. In every case the jacket held in 
place under the clamps but the strand inside moved. Now I have to rent a 
crane with man basket to repair the struts.


The end attachment with three clamps is obviously not a good system. 


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Re: Topband: DC bias tee question

2014-05-21 Thread Tom W8JI

I've been looking at the Shared Apex Loop, and one thing I am puzzled by 
(among many) is that the bias tee/DC coupler circuit has both sides of 
the 75-ohm feed coming in from the antenna and the DC supplied to the 
coupler totally isolated from ground, while the ground side of the coax 
going to the receiver is connected to ground.  Having recently been 
totally defeated in building a bias tee of my own for receive antenna 
switching, I wonder if maybe this is a subtlety of the design that had 
escaped me.



That makes no difference in function.
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Re: Topband: Radar Engineers Model 239

2014-05-13 Thread Tom Miller

Bob K6ZZ  gmail.com> writes:

> 
> By chance does anyone on the list happen to have a repair manual or
> schematic for a Radar Engineers Model 239 RFI Locator?  I have the
> Instruction Manual but it doesn't have much information in it.  Radar
> Engineers doesn't have a service manual or any more information
> available on this unit.  It's about 20 years old best guess.  I have a
> unit that won't power up.
> 
> Thanks, Bob K6ZZ
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
> 
> 

Hi Bob,

I also have one of those receivers and found your message while googling 
for a manual. On mine, the power supply also was dead. At first, I found a 
shorted electrolytic on the power supply board. Replacint that got some 
positive results but there is still a problem and I suspect some more power 
supply issues. There is a resistor ( R556) near the two N-chan mosfets that 
has overheated and I can not read the value. Can you tell me the value of 
that resistor if yours is ok?

Regards,
Tom Miller
WA3PZI
73

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Re: Topband: Ladder line vs coax loss epiphany

2014-04-30 Thread Tom W8JI


That tenuous advantage disappears if one popular 360 ohm heavy duty window
line variant of "450" line is operated at a mismatch. At that point the
stranded copperweld conductors (used for physical strength) start to lose 
a
lot of power at the current maximums of the standing waves. I confirmed 
the

360 ohms on my particular piece of the window line.

In my case, almost 500 feet of that running through the woods needed a
surprising amount of finagling the system to present 360 ohms to the
feedline. That SWR change people see in the rain apparently is a velocity
factor change, making the degree of change in the rain proportional to the
mismatch to the window line Z0. The 450 ohm baluns are not all that good a
match, and most of the baluns are poor at 160..


The ARRL has had some goofy measurements. They had one article that showed 
almost no change in loss with a line laying right on wet dirt!


Lines I measured here with heavy conductors were about 370 ohms, and loss, 
velocity factor, and surge impedance changed with water. They also changed 
substantially when the line was laid against things, or a line enclosed in 
PVC pipe was buried.


It is illogical to have a change in Vf without an accompanying change in 
loss or impedance.


The odd impedance of "450 ohm" lines aggravates the issue of broadband use 
in matched systems. I would stay away from ladder lines for low loss 
impedance matched systems, and stick with real open wire line of a modest 
planned impedance such as 450 ohms.


Surplus hardline is a much better option, IMO.

73 Tom


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Re: Topband: 1000 feet 5/8" hardline or 600ohm True Ladder line.

2014-04-29 Thread Tom W8JI


Paralleling two
runs of line does not decrease the insertion loss.


That depends. Given the same source and load Z as with the single run, it 
does decrease the loss, because the current divides between the two lines. 
The condition that does not reduce the loss is the use of two runs of coax 
wired in series to raise their impedance, so that the center conductors 
are parallel wire line.


Any two cables in parallel have the same loss as a single cable under the 
same condition of mismatch. Power divides equally, loss remains the same in 
each cable. The losses add to the same amount whether in parallel or series. 
The only thing that can change loss is mismatch changes, and that should be 
small on 160.



I wonder just how much different the loss is?



While the shield is important, I don't believe the shield is nearly as 
important as is sometimes made out. Someplace I have hard data on that, 
based on a test fixture that directly excited the shield with a transformer 
over the shield. The fixture was made with two feedthrough connectors and a 
loop of several feet of test cable. Both ports were terminated and measured 
with a selective receiver. The transformer was excited with a known current 
in the shield. I'll have to dig that data out, but I'm pretty sure it was 
somewhere around 80 to 90 dB for thin shield single foil single braid. I'm 
just not sure about the details, but it was a great deal of isolation.


From practical experience, I certainly see no problems in my station. If 

there was a problem, I would be the first to worry about the cable I use.

When I terminate 500 ft runs of F6 style or 3000 ft long runs of single foil 
single shield F11 style cables, they are dead quiet on BC and 160 meters up 
through 15 MHz or more.


If there is a significant common mode, a few cheap beads and/or some grounds 
would be a better investment than new cables.  :)


Far more worrisome are ground paths through devices or improperly installed 
lines.


73 Tom 


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Re: Topband: 1000 feet 5/8" hardline or 600ohm True Ladder lin

2014-04-29 Thread Tom W8JI


Back in 1997 N6BV and I did some testing using "ladder line" (not the real
600 ohm stuff) and some 9:1 baluns on each end.  We were looking at a site
in YV where the beach was about 1000' from the hotel room. We tested the
following:
- loss in back to back baluns
- loss in 100' of ladder line and baluns on each end


When I first moved here I installed a 1500 foot long ladder line with #8 
AWG. With 2.75 inch spacing the #8 bare solid copper was 450 ohm.  This was 
a good spacing for the line, the impedance making the line easy to construct 
and easy to build efficient baluns.


Measured loss on that line was in the .25 dB range on 4 MHz, including 
baluns.


Unfortunately regular window line is neither 450 ohm, or as low loss as is 
published most places (or calculated in some calculators). Some of the ARRL 
stuff shows half the real loss.


73 Tom 


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Re: Topband: Suggestions for a tower?

2014-04-26 Thread Tom W8JI


Tom,

Let's revisit Jaan's original question:

Background:
I have a tower that is 137ft. or 42m tall. It is triangular 1ft 10inches 
or

40cm wide. The tower is guy wired at three levels with non-isolated wire.
The foundation is a concrete slab on on rocky ground.
The surroundings is quite flat and conductivity is perhaps not the best.
About 1/2 mile away I have the Baltic Ocean in almost 360 degrees.

My question is what options do I have to build a good TX antenna out of
this? What can I do? On RX side I will use separate antennas.
I could think of isolating the guy wires or replace them for 
non-conductive
type. I'm not sure if it possible to isolate the base today. Shunt fed 
the

tower, use it as a folded monopole? Or should I just use the tower as a
support for a L-antenna?

73 de Jaan, SM0OEK


What would you recommend?


I wouldn't attempt to suggest someone else do work on a system with a large 
tower with multiple uninsulated guylines and other antenna by guessing.


Guessing is easy, but there are two major problems with design by guessing:

1.) There often are so many things in the near field of any 160 meter 
antenna, that actual patterns and real results are difficult to predict with 
guesses.


2.) If we work what we want to work with satisfaction to ourselves, we 
automatically think we have the best solution possible. This is true even if 
our signals are actually 5-10 dB down from what they could be.


With so many modeling tools available, it would be worth the time to model 
the entire installation. The only difficulty is knowing how to use the 
model.


What I would do is different, and might not be for someone else. If it were 
my installation, the installation would have had insulated or sectionalized 
guylines to start with. I haven't had a tower or mast since 1963 with 
conductive guylines, because I don't want nine or more random things thrown 
into the equation of every low band antenna I plan on trying.


If I was serious about low bands, I would model the tower and see how the 
guylines and other antenna impact all of the bands before doing anything.


If I just wanted to get something on the air without any real effort, I'd 
put up an Inverted Vee dipole and/or an Inverted L and live with it. The 
only real choices are vertical or horizontal. All the differences and any 
possible gain from things like loops and slopers and magical ground and feed 
systems is just a few dB at the most, and no one would notice. The real 
influence is what the tower system looks like electrically, and no one knows 
that..


73 Tom


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Re: Topband: Suggestions for a tower?

2014-04-24 Thread Tom W8JI

The best antenna is always the one that makes us feel good, no matter how 
the antenna really works.


The problems with most of the suggestions are:

1.) most are anecdotal "feelings", where there were no lengthy blind A-B 
tests against a known good reference antenna


2.) different paths and locations produce different results

3.) installations are often cluttered with random things that interact with 
antennas. Even 400-500 feet is fairly close spacing for antennas on 160


Without a series of blind A-B tests against a known *good* antenna over a 
period of time, it is all just feelings. I went through all the grief of 
installing a 300ft plus tall tower because I remembered how well a dipole 
300ft high worked. I can't get someone to use a dipole on that tower once 
they use a tall vertical with a good ground system. I can't get someone to 
use the tall vertical once they use a four square. Going back over my logs 
30+ years ago, I realize the high dipole wasn't actually that good in Ohio. 
I just remembered it better than it was, like a 14-15 second car that I 
thought was a rocket ship.


Someplace below the high dipole's performance come the delta loops and 
sloppers.


Of course this can be different for different regional locations. Not only 
does the quality of the installation affect opinions, so does the mental 
attitude of the operator and the world location.


All that said and done, there are very few properly installed 160 meter 
verticals that won't work well, and there are darned few horizontals that 
will work better than good verticals, when looked at over a long period of 
time. I can't even imagine trying to predict results or give advice when a 
wire is stuck in between a bunch of random things, like conductive guylines 
and other antennas.


73 Tom 


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Re: Topband: How Increase 160m power on FL2100z


So i ll do some mods during the week , 1st add some capacitance on the Load
in // to c32 en cie... I ll begin with 470p more and do the test and
increase...

Once ok I ll add some inductance on the 160m circuit with a torroid T-200 +
some 10 turns ,and I ll have to found a place to put inside)>>>

If you are doing work you may as well do it correctly. Adding tank 
inductance will probably fix the entire problem, plus give you more matching 
range and sharper tuning. Then you can probably remove capacitance.


73 Tom



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Re: Topband: How Increase 160m power on FL2100z

A proper tank would be about 300-330 pF on the tune side (allowing for plate 
choke reactance) and 2000 pF on the load. This requires 33 uH on the total 
inductance.


Yaesu has way too little tank inductance and that causes the capacitance to 
be excessive. This puts the Q up in the 20 range, which is not necessary.


It is possible it has an open load padding capacitor, because they are 
notorious for going open, but the real fix is to correct the tank by 
increasing inductance (which reduces loaded Q) so it "acts normal".



73 Tom

- Original Message - 
From: "JC N4IS" 

To: 
Sent: Sunday, April 20, 2014 10:57 AM
Subject: Re: Topband: How Increase 160m power on FL2100z



I owned a FT2100Z for several years and the power on 160m was the same as
other bands. I don't expect any design flaw. The original tubes are not
available anymore, the  572's tubes manufactures nowadays are different 
and

optimized for audio applications and does not perform at the same level as
the originals 572's. You may just need more drive or change the input
circuit for 160m.

Regards
N4IS


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-
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Re: Topband: How Increase 160m power on FL2100z


Damien,

"Load" button on 160m is always at "0" "ccw" even on 1810khz or 1900khz,
just the "plate" get some influence "1" in CW part and "3" at 1850 for
example.>>>

This indicates not enough loading capacitance or not enough tank inductance, 
especially if plate current is high and grid current low.


Low or inadequate operating Q is indicated by a load control working 
backwards from normal, or having no effect at all as you move the control.


Current IP at 500mA give 400w out on 160m , 700w on 80 and 40m ...
still until 550w on 10m but the PA only used on 160m , sometimes on 80 but
rare.>>>>

Indicates lack of loading capacitance, especially if grid current is also 
proportionally low.


For 90w IN : 1810Khz 440w  1900Khz 490w  load 0plate0
at 1810/ 3 at 1900 but 550mA current for this for + 100 good
watts in.
So more power on higher frequency on the band.>>>>

Indicates lack of loading capacitance or tank inductance.

PA0FRI on his website , on his article about the fl2100z you can read :"The
lower output on the 160 m band is due to the very low Q of the anode
circuit, because the manufacturer has cut the components. The lower power on
the higher bands is due to the decreasing efficiency of the tubes and the
higher circuit losses on the higher frequencies.">>>>

I would not trust a thing on that website.

Anode operating impedance is closely  RMS RF anode voltage^2 / Pout =  Rp

Approximately 1700^2 / 600 = 4800 ohms at 600 watts

Looking at the FL2100 values, it looks like they have a loaded tank Q in the 
20's. They have unnecessary high Q, not too little. This is why they run out 
of loading capacitance. They need almost 3500-4000 pF with that operating Q. 
You could add shunt capacitance. The only ill effect would be lack of range 
(delta C) in the controls because of the large padding capacitances.


The actual cause is from lack of tank inductance on 160 meters. While you 
can work around that by increasing padding capacitance, a better solution 
would be to increase tank coil inductance on 160 meters. You might add a 
small toroid inductor like a T-200-2 between the 160 meter end of the coil 
and the switch/loading cap connection.


If that were my amp and I wanted to test this, I would temporarily stick 
a -2 iron core in the cold end of the tank coil and see if output increases. 
This would prove the benefit of more inductance (which would actually reduce 
tank operating Q).


Many amplifiers of that age, because of size required for 160 meter coils, 
did not have enough tank inductance. This is very common for Dentron and 
others. Some have close to the proper inductance with the cover removed, and 
when the cover is installed the inductance falls too low. While it is unsafe 
and should never be done, sometimes removing the cover restores performance 
by increasing tank inductance when the coil is near the cabinet. Dentron is 
bad about this.


73 Tom 


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Re: Topband: How Increase 160m power on FL2100z