[Antennas] Thanks for Loop advice

[John Lawson]

   I orginally posted a message or two to a couple of other Lists I'm 
subbed to - concerning my backyard HF Loop antenna.  I got a great deal of 
very good advice back from folks here to took the time to write me 
personally.  I have of course, now subscribed to this List.

   Because of the usual new-housing-development strictures, and also 
because I don't plan to stay in this house forever - I have run a loop of 
#14 hard-drawn copper around my back (wooden) fence that is 5' above 
ground and about 430 feet total circumference, although it is square - it 
is fed near one corner with 450 ladder-line back (kept away from metal 
things) to an Ameritron ATR-15 tuner. A Johnson Valiant drives this mess.

   The antenna as first installed performed very well on 80m, nicely on 
160, and gave a 2:1 on 20M.  The other bands would not tune below +3:1 and 
were hopeless.

   Several folks suggested parallel capacity, and others advised adding 10' 
or so to the feedline in the shack. I have a large DPDT (actually two 
side-by-side SPDT units) switch on the feedline, that I originally was 
going to use to ground the system, and perhaps cut in some 'anti-charging' 
resistors - as here in the high desert of northern Nevada - the ground is 
dry and sandy, the humidity typically below 10%, and the thunderstorms 
frequent.  Instead, I attached two caps - one a 150pF mica and one a 350 
pF mica - both are high-current transmitting devices.

   Now with the 150 pF capacitor paralleled across the ladder-line - I can 
get down to 1.3:1 on 160M, 1.5:1 on 80M, 2.0:1 on 40M, and 1.5:1 on 20M 
(with the proviso that the ATR bandswitch must be on the 40M position for 
the 20M band). Using the 350pF make this 'worse' across the board - so I 
didn't bother with it.

   Therefore I have improved my higher-band situation a great deal.

   Next I'll splice in 10' more of feedline, and also use smaller (than 
150pF) cap in parallel.  I do have a Palomar noise bridge - and I used 
that to get a 'feel' for the intial settings - but there's nothing like a 
couple of hundred watts to actually see how things sort themselves out.

   Again, my thanks to the ListMembers who have helped me out - I have 
EZNec and am learning to use it - but there's nothing like the few hundred 
years of accumulated practical experience that can be found here.

   Thanks so much - and more to come!

   I also look forward to QSOs on AM Fone - mainly on 80M in the evenings 
Pacific time.

Cheers

John   KB6SCO
Carson City, NV