[Elecraft] Fw: Balun Ground Connection

[Richard Fjeld]

John,
It is unfortunate that we can't see a schematic of how the balun is wired. 
I have thought of doing that same thing to be able to use an ATU. 
Presently, I have an 80 meter loop fed with homebrew 450 ohm ladder line to 
a tuner with a 1:1 balun within.  It works beautifully on all bands.  I wish 
I had done it many years ago.

As for your grounding the coax at both ends, I effectively do that here also 
on my coax switch with coax to my K3 which is also grounded.  So that is why 
it would be necessary to see the schematic to see what is different about 
your situation.

I can tell you that I have everything grounded to a 'ground tree', or earth 
tree as our friends call it.  I buried a 6 ga. wire from the central point 
over to my tower.  I grounded it at 2 or 3 places along the way, and the 
tower is grounded at each leg with a separate ground rod.  When I did make 
the final connection to the tower ground, I saw a change in the swr of my 
beams which are at DC ground, and coax fed again similar to what you are 
doing.  The swr got higher, but not bad.  Maybe it went up point five or 
less.  From my experience, any time I change ANYTHING relating to my antenna 
system, the SWR changes.

As for #2, the common mode current, I thought a balun is supposed to stop 
that from happening.

Rich, n0ce

----- Original Message ----- 
From: <zendoc at netspace.net.au>
To: "'Jim Harris'" <jim.w0em at yahoo.com>; <zendoc at netspace.net.au>; 
"'Elecraft Email'" <elecraft at mailman.qth.net>
Sent: Thursday, September 20, 2012 4:50 PM
Subject: Re: [Elecraft] Balun Ground Connection


> Hi Jim & group
>
> I did an experiment today and tied the balun case/coax shield to station 
> ground via the stud.
>
> I found 2 things:
>
> # 1 the manual tuner settings required for 1:1 match changed on all bands, 
> but the KAT3 and manual tuner were still able to find a 1:1.0 match on all 
> bands 80m - 10m.
>
> #2 where I had no detectable common mode current on the coax shield prior 
> to connecting the balun to ground, I now have 15-20mA on 20 and 40m, as 
> measured with my calibrated clip on ammeter.  There's also now some RF on 
> my tx audio, where before it was clean.
>
> I'm wondering if the coax shield between the balun and tuner IS 
> functioning as part of this loop antenna system and grounding its shield 
> before the tuner  is introducing more imbalance?
>
> I'm no expert, but this is interesting.
>
> 73,
> John
> VK7JB
>
>
>
> -------- Original Message ----------
>
>
>
> John,
> I found that by connecting the balun ground to my station ground I
> had >25 SWR on all bands. I just let it float......no problems so far.
>
> 73
> Jim, W0EM
> >>>
> John
> VK7JB
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html