[Elecraft] Balun Ground Connection

[Jim Harris]

John,
I'm not surprised at your findings in light of my experience.  Regarding the ATUs being able to tune in this case, I'm not surprised.  Elecraft tuners will match nearly a complete open and short.......been there, done that.  I really wish they were limited to something like 6:1 to prevent that.  Above that SWR RF energy is grossly wasted, IMHO.
It seems for some reason that I don't know about at the moment, when the balun case ground is connected to station ground it somehow makes a major change in the antenna/coax system.  I've replaced most of the coax in all my antenna systems in the last month so I'm leaning toward some other explanation.  When I get some spare time this weekend I will try to take a further look at it.

73



Jim, W0EM

--- On Thu, 9/20/12, zendoc at netspace.net.au <zendoc at netspace.net.au> wrote:

From: zendoc at netspace.net.au <zendoc at netspace.net.au>
Subject: Re: Balun Ground Connection
To: "'Jim Harris'" <jim.w0em at yahoo.com>, zendoc at netspace.net.au, "'Elecraft Email'" <elecraft at mailman.qth.net>
Date: Thursday, September 20, 2012, 9:50 PM

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