[Elecraft] Balun at input or output of tuner

[Jim Brown]

On 12/13/2011 12:53 PM, David Herring wrote:
> I'd like to ask a few questions.

David,

I hardly know where to begin in responding to your question. First, if 
you want a self-supporting vertical antenna for 30-10M, there are some 
really good choices that you can buy, that can be easily installed, that 
can be fed with 50 ohm coax, that don't require radials, and that don't 
require a balanced tuner. Loss in the feedline should be quite small if 
you use RG8 (or even RG8X). Look at the Hy-Gain AV-640, which one of my 
friends has used to work a lot of DX and do contesting from a small city 
lot. You should use one of my chokes at the feedpoint of this antenna. 
See my RFI tutorial, previously referenced.

IMO, balanced tuners and so-called balanced line are highly over-rated 
solutions to problems that don't exist, or that could be better solved 
with other far simpler and less costly means.  IMO, the only GOOD use of 
high impedance parallel wire feedlines is for very long runs -- 500 ft 
or more. Likewise, I am not a fan of all-band non-resonant dipole 
antennas, primarily because it is mechanically difficult choke them at 
their feedpoint, which makes them noisy and puts RF on the feedline, but 
also because their directional patterns vary widely with frequency.  
Since you're trying to make a vertical work on all bands, I'm assuming 
that horizontal antennas are not practical for you, hence the 
recommendation for the AV-640.  I'm not a fan of compact, multi-band 
verticals below 40M because their efficiency tends to be poor, but at 
30M and above they can work quite well.

As to RF in the shack -- nearly all RF in the shack problems are the 
result of Pin One Problems in equipment. See the RFI tutorial for an 
explanation and solutions.  Also see the pdf on Ham Interfacing for 
detailed instructions about bonding all of your gear together with short 
lengths of copper wire. This kills hum and buzz, and makes a big dent in 
the RFI you're experiencing.  In extreme cases you may need to add 
chokes to individual cables.

http://audiosystemsgroup.com/publish.htm

73, Jim K9YC