Re: Topband: Series LC to notch AM broadcast ?

[Richard (Rick) Karlquist]

On 2/20/2022 9:41 AM, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE offending AM
broadcast station ?  I'm talking about wiring from hot side of coax...to



Jim   VE7RF
_


See:

MFJ-8504AN, AM Notch Filter

73
Rick N6RK
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: TV coax + F-connectors

[Richard (Rick) Karlquist]

On 2/20/2022 7:46 AM, Radio KH6O wrote:


Reading the comments about possible lack of uniform impedance and
other short-comings, I remind myself that I'm an amateur, not a
professional. A few milliwatts loss doesn't concern me.



73, Jeff KH6O
_


The issue of non-uniform impedance and VF vs frequency is not one
of "amateur vs professional", but rather simple antennas vs phased
arrays.  Junky coax can noticeably mess up the array pattern.

73
Rick N6RK


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Re: Topband: Series LC to notch AM broadcast ?

[Jeff Blaine]

The secret to using this sort of solution is to apply just enough of it 
to kill off the mixing products that are the result.  The good news is 
that you get (generally speaking) a 3:1 payback - so 1 db attenuation of 
the BC station will knock the mixing product down by 3 dB.  So 45 dB (as 
the article provides) is not needed to get meaningful mitigation.


The L/C ratio does set the Q of the notch.  And a series R can cut down 
on the notch depth, as well as reducing the SWR impact. There is a 
balancing act between these factors but generally the highest Q, and 
maximum R combo that is stable enough over the temp range, will do the job.


Have fun!

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 2/20/22 8:42 PM, donro...@hiwaay.net wrote:

We had a 1550khz in town and a 1450khz moved 2 blocks away from 1550.

Yep mix products on 1650khz and 1350khz. ( and to some extent 
1500khz )


a simple 1550 notch on the top of the 1450 transmitter eliminated the 
mix products and didn't bother the 1450 transmitter.


Don W4DNR

On 2022-02-20 12:14 pm, Nick Hall-Patch via Topband wrote:


Hello Jim,

Better, I think, is this notch, found at the IRCA Reprints:

https://www.ircaonline.org/editor_upload/File/reprints/irca-reprint-index.pdf 



Look for Reprint A-063, An RF Notch Filter by VE6JY.

You really should only need to notch the carrier of the offending AM 
station, as  that's where the bulk of the overload will be coming  
from.  It's a pretty amazing device, in my estimation.


73

Nick

VE7DXR

At 17:41 2022-02-20, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE 
offending AM
broadcast station ?  I'm talking about wiring from hot side of 
coax...to

chassis / groundlike via a T connector etc.

On paper, it should work. Did some minor research, and one comment 
was that
by using higher values of L would result in  higher Q..and a deeper 
notch.
Another comment stated to use some initial values, like what spits 
out on a
L-C  online calculator for practical values. then multiply one 
value
by the other...then take the square root of the result.   Then you 
ended up
with 2 x numerically equal values of L + C. and supposedly the 
greatest

notch depth.

On software, I tried several values..from one extreme to the other, and
they all resonate on the same freq.   Also tried in software, using 2 x
numerically same values..and it too, also resonates on the same freq.

The rationale behind all of this is... in some cases, there is only one
offending AM broadcast station.  Typ  HP  filters offer little 
rejection

towards the top end of the AM broadcast band. like 1200-1710 khz.

I would like to try it, but am still confused as to which combo (using
practical values) will result in the deepest notch.  It would have 
to be
wide enough to remove the 20 khz wide AM signal.  A fixed coil + 
variable

cap, or padded variable cap could be used to fine tune the notch freq.

Perhaps   2 or more LC filters could be used in parallel, to notch 
out 2 or

more offending stations ?

Jim   VE7RF
_
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Reflector


Nick Hall-Patch
Victoria, BC
Canada _
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Reflector

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Re: Topband: Series LC to notch AM broadcast ?

[donroden]

We had a 1550khz in town and a 1450khz moved 2 blocks away from 1550.

Yep mix products on 1650khz and 1350khz. ( and to some extent 
1500khz )


a simple 1550 notch on the top of the 1450 transmitter eliminated the 
mix products and didn't bother the 1450 transmitter.


Don W4DNR

On 2022-02-20 12:14 pm, Nick Hall-Patch via Topband wrote:


Hello Jim,

Better, I think, is this notch, found at the IRCA Reprints:

https://www.ircaonline.org/editor_upload/File/reprints/irca-reprint-index.pdf

Look for Reprint A-063, An RF Notch Filter by VE6JY.

You really should only need to notch the carrier of the offending AM 
station, as  that's where the bulk of the overload will be coming  
from.  It's a pretty amazing device, in my estimation.


73

Nick

VE7DXR

At 17:41 2022-02-20, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE offending 
AM
broadcast station ?  I'm talking about wiring from hot side of 
coax...to

chassis / groundlike via a T connector etc.

On paper, it should work. Did some minor research, and one comment was 
that
by using higher values of L would result in  higher Q..and a deeper 
notch.
Another comment stated to use some initial values, like what spits out 
on a
L-C  online calculator for practical values. then  multiply one 
value
by the other...then take the square root of the result.   Then you 
ended up
with 2 x numerically equal values of L + C. and supposedly the 
greatest

notch depth.

On software, I tried several values..from one extreme to the other, 
and
they all resonate on the same freq.   Also tried in software,  using 2 
x

numerically same values..and it too, also resonates on the same freq.

The rationale behind all of this is... in some cases, there is only 
one
offending AM broadcast station.  Typ  HP  filters offer little 
rejection

towards the top end of the AM broadcast band. like  1200-1710 khz.

I would like to try it, but am still confused as to which combo (using
practical values) will result in the deepest notch.  It would have to 
be
wide enough to remove the 20 khz wide AM signal.  A fixed coil + 
variable

cap, or padded variable cap could be used to fine tune the notch freq.

Perhaps   2 or more LC filters could be used in parallel, to notch out 
2 or

more offending stations ?

Jim   VE7RF
_
Searchable Archives: http://www.contesting.com/_topband - Topband 
Reflector


Nick Hall-Patch
Victoria, BC
Canada _
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Reflector

_
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Re: Topband: Series LC to notch AM broadcast ?

[Jim Brown]

On 2/20/2022 3:33 PM, Grant Saviers wrote:
Somewhat related was my effort to produce a pair of 80m notches so CW 
and SSB could run 80m simultaneously on Field Day (separate antennas). 
While the CW guys would be ok with 20KHz BW, not so for the SSB team. 
Just below a Rx 40db notch was about the best I could do with a one db 
loss Tx.


For CQP county expeditions, we've often run CW and SSB on 80 at the same 
time, also on 40, using K3 and KPA500, with nothing more than resonant 
half-wave dipoles carefully sited colinear, separated by 250-300 ft, and 
serious chokes at each feedpoint. The chokes are important -- they 
prevent feedline pickup from filling in the nulls.


For 7QP, we rig a 2-el 20M Yagi a few feet above a 40M dipole, with an 
80M inverted V just below that, also a pair of K3s, KPA500s, and 
carefully located double stubs to kill 2nd harmonic on CW. We also have 
W3NQN BPFs on both radios. They're part of W6GJB's contesting trailer, 
documented in these slides, but before Glen built the 2-el 20M folding 
Yagi. And we're rigging them closer now. k9yc.com/7QP.pdf  Again, chokes 
at the feedpoints are critical -- we forgot once (thankfully the day 
before in Glen's driveway), and it blew the isolation. And, of course, 
nothing will help passive IMD generated outside the RF chain.


73, Jim

_
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Re: Topband: Series LC to notch AM broadcast ?

[n4is]

>>HP  filters offer little rejection towards the top end of the AM broadcast
band. like  1200-1710 khz. <<

I built several HP filters with >40 db attenuation on 1.7 KHz based on QST,
I don't remember the year 90's about it.

But  some good information here >

https://www.qsl.net/wb5wpa/Filter/DesignAMBrickWall_08.pdf

You can but a 200W HP at DXE, this filter is the best you can get and very
well calibrated/built.

https://www.dxengineering.com/parts/dlw-fl1718

73'
N4IS
JoseCarlos



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Re: Topband: Series LC to notch AM broadcast ?

[Mike Waters]

Being the simplistic cheapskate that I am, I got rid of all my AM IMD with
a 2k pot in the receive line. :-)

Tip from W8JI about 40 years ago. Just attenuate everything. Works for me.

73 Mike
W0BTU

On Sun, Feb 20, 2022 at 11:42 AM jim.thom jim.t...@telus.net <
jim.t...@telus.net> wrote:

> Has anybody tried using a simple series L-C to notch out ONE offending AM
> broadcast station ?
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Series LC to notch AM broadcast ?

[Grant Saviers]

Somewhat related was my effort to produce a pair of 80m notches so CW 
and SSB could run 80m simultaneously on Field Day (separate antennas). 
While the CW guys would be ok with 20KHz BW, not so for the SSB team. 
Just below a Rx 40db notch was about the best I could do with a one db 
loss Tx.


Anyway, the free filter calculator ELSI was a big help, since plots were 
important to minimize out of notch loss that would withstand 100w.

http://tonnesoftware.com/elsie.html

What I also found in playing with off the shelf inductors for this and 
 matching a passive 4sq Rx antenna (W8JI top loaded design), was that 
some of the cheap "20 values" inductor kits on ebay had pretty high Q's 
vs Digikey catalog ones.  Then silver micas were paralleled to get the 
right C value for whatever the L value measured.


I'm sure there is much more expert help available ;).

Grant KZ1W

On 2/20/2022 09:41, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE offending AM
broadcast station ?  I'm talking about wiring from hot side of coax...to
chassis / groundlike via a T connector etc.

On paper, it should work. Did some minor research, and one comment was that
by using higher values of L would result in  higher Q..and a deeper notch.
Another comment stated to use some initial values, like what spits out on a
L-C  online calculator for practical values. then  multiply one value
by the other...then take the square root of the result.   Then you ended up
with 2 x numerically equal values of L + C. and supposedly the greatest
notch depth.

On software, I tried several values..from one extreme to the other, and
they all resonate on the same freq.   Also tried in software,  using 2 x
numerically same values..and it too, also resonates on the same freq.

The rationale behind all of this is... in some cases, there is only one
offending AM broadcast station.  Typ  HP  filters offer little rejection
towards the top end of the AM broadcast band. like  1200-1710 khz.

I would like to try it, but am still confused as to which combo (using
practical values) will result in the deepest notch.  It would have to be
wide enough to remove the 20 khz wide AM signal.  A fixed coil + variable
cap, or padded variable cap could be used to fine tune the notch freq.

Perhaps   2 or more LC filters could be used in parallel, to notch out 2 or
more offending stations ?


Jim   VE7RF
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
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Re: Topband: TV coax + F-connectors

[Mike Waters]

On Sun, Feb 20, 2022, 2:55 PM Jim Brown  wrote:

> On 2/20/2022 10:53 AM, Mike Waters wrote:
> > And RG-6 has a power handling curve very similar to RG-213.
>
> WRONG! This may be true of SOME RG6 cables, but definitely NOT true of
> many.
>

Point well taken, Jim! I actually use a couple different types of Commscope
F-6, bonded aluminum foil with braid(s).

73 Mike
W0BTU

>
_
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Re: Topband: Array of MiniWhips?

[Lee STRAHAN]

Hello Ash,
   It depends on how complex an array you want to build  as to whether these 
amps would work OK. Two or three elements might work fine.
  There are several things that concern me about these amps. I do not have 
the time to test them here however.
First there is no way to make sure the gain would be equal between several 
amps as the gain in these amps is pretty well
defendant on the semiconductor gain parameters and operating currents.
Secondly there is no protection against static discharges on the elements. 
Or induced currents in the feedline for that matter. If you are near any winter 
storms or lightning events 
I don't think the amps would survive.
The third item is that the output impedance of this amp is just a few ohms 
due to transistor operating current, transistor  Beta, and Rb parameters, plus 
more and each amp would likely be different causing 2 things. One is gain 
change and the other is driving a coaxial cable off the design impedance will 
cause extra phase shifts not intended. Yes, I know if one end of a coax is 
terminated there is supposed to be no unintended phase shifts however I have 
found with typical RG-6 coax cables, impedance tolerances, and typical matching 
transformers etc it is best to match coax impedance at both ends which has 
produced much better results and predictable results here. To fix this would 
require the amp to have a 75 ohm output impedance. 
The last item is, it is my belief that this amp would not have a very high 
second order IMD capability and if you were too close to any broadcast band 
high power stations it could be a problem. 
   Lee  K7TJR  OR


-Original Message-
From: Topband  On Behalf Of 
Ashraf Chaabane
Sent: Sunday, February 20, 2022 11:43 AM
To: VE6WZ_Steve 
Cc: topband ; Boubaker Ahmed 
Subject: Re: Topband: Array of MiniWhips?

Hi Steve,

Thanks for your email and information.

We've been looking at the preamp design again but didn't manage to confirm if 
it would deliver accurate phase/amplitude.

Can you (or anyone here) check the design and advise. It can be found
here: http://www.kiwisdr.com/docs/pa0rdt_whip.pdf

If an array of Miniwhips can fly, it would be a perfect solution for us.

73 Ash 3V8SS 3V8SF


On 19/02/2022 16:49, VE6WZ_Steve wrote:
> Hello Ash,
>
> The small vertical (HI-z) arrays like the 8 circle and 9 circle depend on 
> VERY accurate phase and amplitude between elements.
> Even small variation in amplitude, or phase can destroy the pattern and RDF 
> which is what makes these arrays effective.
>
> The HI-z amplifiers used in these arrays have very accurate phase and 
> amplitude which is normalized between all units.
> I do not know what the PA0RDT amps are like, but this is a crucial thing you 
> need to look at.
>
> 73, de steve ve6wz
>
>> On Feb 19, 2022, at 1:25 AM, Ashraf Chaabane  wrote:
>>
>> Hi All,
>>
>> We recently built a couple of PA0RDT MiniWhip antennas that worked fine on 
>> low bands (seehttp://www.kf5eyy.info/technical.htm) and we wonder if these 
>> were used by anyone to make a steerable array.
>>
>> Please advise.
>>
>> 73 Ash 3V8SF 3V8SS
>>
>> www.kf5eyy.info
>> _
>> Searchable Archives:http://www.contesting.com/_topband  - Topband 
>> Reflector
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Re: Topband: TV coax + F-connectors

[Jim Brown]

On 2/20/2022 10:53 AM, Mike Waters wrote:

And RG-6 has a power handling curve very similar to RG-213.


WRONG! This may be true of SOME RG6 cables, but definitely NOT true of 
many.


For at least 50 years, RG numbers have not been a spec, but rather a 
general description defining impedance and approximate outer diameter. 
There are hundreds of RG6 cables, many of them quite different from each 
other, and there are many different connectors. There are 63 "RG6 type" 
cables in what is probably the last printed version of Belden's catalog 
(from 2006).


The vast majority of RG6-type cables are made for MATV and CATV 
applications, with copper-coated steel centers and Al foil/braid 
shields, and the number of those braids and foils varies from one to four.


There's at least one RG6 in the Belden catalog with a solid copper 
center and a double copper braid shield. I have some of a 
Pasternak-branded cable that appears to be built to that spec, and I 
suspect it was for analog video inside studios. I also have about 500 ft 
of a very similar Belden RG11, also designed for analog video.


73, Jim K9YC
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Series LC to notch AM broadcast ?

[Jim Brown]

On 2/20/2022 9:41 AM, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE offending AM
broadcast station ?


Sure -- although I don't remember doing it, I knew about it almost from 
when I was first licensed 65 years ago.


73, Jim K9YC


_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Array of MiniWhips?

[Ashraf Chaabane]

Hi Steve,

Thanks for your email and information.

We've been looking at the preamp design again but didn't manage to 
confirm if it would deliver accurate phase/amplitude.


Can you (or anyone here) check the design and advise. It can be found 
here: http://www.kiwisdr.com/docs/pa0rdt_whip.pdf


If an array of Miniwhips can fly, it would be a perfect solution for us.

73 Ash 3V8SS 3V8SF


On 19/02/2022 16:49, VE6WZ_Steve wrote:

Hello Ash,

The small vertical (HI-z) arrays like the 8 circle and 9 circle depend on VERY 
accurate phase and amplitude between elements.
Even small variation in amplitude, or phase can destroy the pattern and RDF 
which is what makes these arrays effective.

The HI-z amplifiers used in these arrays have very accurate phase and amplitude 
which is normalized between all units.
I do not know what the PA0RDT amps are like, but this is a crucial thing you 
need to look at.

73, de steve ve6wz


On Feb 19, 2022, at 1:25 AM, Ashraf Chaabane  wrote:

Hi All,

We recently built a couple of PA0RDT MiniWhip antennas that worked fine on low 
bands (seehttp://www.kf5eyy.info/technical.htm) and we wonder if these were 
used by anyone to make a steerable array.

Please advise.

73 Ash 3V8SF 3V8SS

www.kf5eyy.info
_
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Re: Topband: TV coax + F-connectors

[Mike Waters]

I can testify that F connectors with RG-6 will handle the legal limit on at
least 160 and 80 without even getting warm.

This is true here with 2500 watts into a dummy load and CW contesting.

I waterproof mine by partially filling them with silicone dielectric
grease. Been doing that here for many years without a single problem.
Outdoors, I use waterproof F connectors.

If you use RG-6, the rough points on the center conductor should be filed
smooth with a small fine file. Otherwise, the contacts in the male
receptacle can be damaged.

And RG-6 has a power handling curve very similar to RG-213.

73 Mike
W0BTU
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Series LC to notch AM broadcast ?

[Nick Hall-Patch via Topband]

Hello Jim,

Better, I think, is this notch, found at the IRCA Reprints:

https://www.ircaonline.org/editor_upload/File/reprints/irca-reprint-index.pdf 



Look for Reprint A-063, An RF Notch Filter by VE6JY.

You really should only need to notch the carrier of the offending AM 
station, as  that's where the bulk of the overload will be 
coming  from.  It's a pretty amazing device, in my estimation.


73

Nick

VE7DXR

At 17:41 2022-02-20, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE offending AM
broadcast station ?  I'm talking about wiring from hot side of coax...to
chassis / groundlike via a T connector etc.

On paper, it should work. Did some minor research, and one comment was that
by using higher values of L would result in  higher Q..and a deeper notch.
Another comment stated to use some initial values, like what spits out on a
L-C  online calculator for practical values. then  multiply one value
by the other...then take the square root of the result.   Then you ended up
with 2 x numerically equal values of L + C. and supposedly the greatest
notch depth.

On software, I tried several values..from one extreme to the other, and
they all resonate on the same freq.   Also tried in software,  using 2 x
numerically same values..and it too, also resonates on the same freq.

The rationale behind all of this is... in some cases, there is only one
offending AM broadcast station.  Typ  HP  filters offer little rejection
towards the top end of the AM broadcast band. like  1200-1710 khz.

I would like to try it, but am still confused as to which combo (using
practical values) will result in the deepest notch.  It would have to be
wide enough to remove the 20 khz wide AM signal.  A fixed coil + variable
cap, or padded variable cap could be used to fine tune the notch freq.

Perhaps   2 or more LC filters could be used in parallel, to notch out 2 or
more offending stations ?


Jim   VE7RF
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector


Nick Hall-Patch
Victoria, BC
Canada 
_

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Re: Topband: Series LC to notch AM broadcast ?

[Joe]

I will try if you are or anyone is interested getting the design of this 
filter we use on a AM radio broadcast antenna when we use it on 160 Meters.


This is NOT just a matching unit to match the antenna for us to use on 
160 meters. BUT also a pass band filter for 160, a High pass filter 
blocking anything below 160 meters, AND a notch filter tuned to the AM 
Transmitters frequency.


WHY? The Notch?  Because we use this WHILE THE AM TRANSMITTER IS STILL 
TRANSMITTING!!!


Yes we have played on 160 meters with this magic box while the AM 
station is still on the air.


Talk about isolation!

Joe WB9SBD / W9ET

On 2/20/2022 11:41 AM, jim.thom jim.t...@telus.net wrote:

Has anybody tried using a simple series L-C to notch out ONE offending AM
broadcast station ?  I'm talking about wiring from hot side of coax...to
chassis / groundlike via a T connector etc.

On paper, it should work. Did some minor research, and one comment was that
by using higher values of L would result in  higher Q..and a deeper notch.
Another comment stated to use some initial values, like what spits out on a
L-C  online calculator for practical values. then  multiply one value
by the other...then take the square root of the result.   Then you ended up
with 2 x numerically equal values of L + C. and supposedly the greatest
notch depth.

On software, I tried several values..from one extreme to the other, and
they all resonate on the same freq.   Also tried in software,  using 2 x
numerically same values..and it too, also resonates on the same freq.

The rationale behind all of this is... in some cases, there is only one
offending AM broadcast station.  Typ  HP  filters offer little rejection
towards the top end of the AM broadcast band. like  1200-1710 khz.

I would like to try it, but am still confused as to which combo (using
practical values) will result in the deepest notch.  It would have to be
wide enough to remove the 20 khz wide AM signal.  A fixed coil + variable
cap, or padded variable cap could be used to fine tune the notch freq.

Perhaps   2 or more LC filters could be used in parallel, to notch out 2 or
more offending stations ?


Jim   VE7RF
_
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Topband: Series LC to notch AM broadcast ?

[jim.thom jim.t...@telus.net]

Has anybody tried using a simple series L-C to notch out ONE offending AM
broadcast station ?  I'm talking about wiring from hot side of coax...to
chassis / groundlike via a T connector etc.

On paper, it should work. Did some minor research, and one comment was that
by using higher values of L would result in  higher Q..and a deeper notch.
Another comment stated to use some initial values, like what spits out on a
L-C  online calculator for practical values. then  multiply one value
by the other...then take the square root of the result.   Then you ended up
with 2 x numerically equal values of L + C. and supposedly the greatest
notch depth.

On software, I tried several values..from one extreme to the other, and
they all resonate on the same freq.   Also tried in software,  using 2 x
numerically same values..and it too, also resonates on the same freq.

The rationale behind all of this is... in some cases, there is only one
offending AM broadcast station.  Typ  HP  filters offer little rejection
towards the top end of the AM broadcast band. like  1200-1710 khz.

I would like to try it, but am still confused as to which combo (using
practical values) will result in the deepest notch.  It would have to be
wide enough to remove the 20 khz wide AM signal.  A fixed coil + variable
cap, or padded variable cap could be used to fine tune the notch freq.

Perhaps   2 or more LC filters could be used in parallel, to notch out 2 or
more offending stations ?


Jim   VE7RF
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: TV coax + F-connectors

[Joe]

Greetings.

I do not know if they still do use them.

But the MAJOR Amateur AND PROFESSIONAL antenna maker M Squared uses "F" 
connectors in their antennas ALL the time.


They even use a variation that is weatherproof.
They use them from below 1 meg antennas up to antennas in the Gig 
ranges. Mainly at the feedpoint to connect the phasing line in the 4 to 
1 balun feed design.



Joe WB9SBD / W9ET

On 2/20/2022 9:46 AM, Radio KH6O wrote:

Colleagues,

I was very happy to see the discussion regarding the use of television
feedline and F-connectors. I thought I was the only ham in the
universe using that combination. While it's true that the connectors
are not weather-resistance, a coating of black asphalt sealant* takes
care of that.

Reading the comments about possible lack of uniform impedance and
other short-comings, I remind myself that I'm an amateur, not a
professional. A few milliwatts loss doesn't concern me.

* For 
example:https://www.lowes.com/pd/Henry-Company-Asphalt-Emulsion-1-Gallon-Waterproofer-Roof-Sealant/50255565

73, Jeff KH6O
_
Searchable Archives:http://www.contesting.com/_topband  - Topband Reflector


_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: TV coax + F-connectors

[Radio KH6O]

Colleagues,

I was very happy to see the discussion regarding the use of television
feedline and F-connectors. I thought I was the only ham in the
universe using that combination. While it's true that the connectors
are not weather-resistance, a coating of black asphalt sealant* takes
care of that.

Reading the comments about possible lack of uniform impedance and
other short-comings, I remind myself that I'm an amateur, not a
professional. A few milliwatts loss doesn't concern me.

* For example: 
https://www.lowes.com/pd/Henry-Company-Asphalt-Emulsion-1-Gallon-Waterproofer-Roof-Sealant/50255565

73, Jeff KH6O
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector