"Wes Stewart" wrote in message
...
On Sun, 28 Aug 2005 12:57:06 GMT, "Bill Smith"
wrote:

Hello all,
My station consisted of an Icom 706MKIIG, the AH-4 tuner and a 360ft loop
at
60 feet. The tuner is mounted at the loop on the roof with about 100ft of
coax to the rig.

I just purchased a Kenwood TS-870s with built in tuner. I'm running it on
the same feedline and thru the unpowered AH-4. The built in tuner works
fine
and all seems good.

Question: I want to remove the AH-4 to go with my 706 for mobile/remote
use.
Would a 1:1 balun work in place of the AH-4 to connect the loop to the
feedline? I work 15 thru 80 most of the time.


Smitty,

I have more questions than answers. The AH4 is designed to match a
single wire (whip) antenna working against ground as best I can
figure.

http://home.comcast.net/~hamlakemn//ah4/ah4.htm

You say your loop is at 60' but the tuner is on the roof at the loop.
Is the roof 60' high?

Is this a real closed loop? If so how is the tuner connected?

With more loop parameters known, maybe it could be modeled to
determine whether a balun will function okay and whether the mismatch
on the coax will be acceptable.

What kind of coax are you using?

The '870 is a fine radio...got one myself.

--------------------------------
Hello Wes,
The loop is setup on a large, flat roof of a local business, atop 15 ft
masts. Building is a 4 story brick & wood building (built in1907). No steel.
One end of the loop is attached to the output (+) of the AH4, other end of
the loop is attached to the ground lug of the AH4. Coax is an RG-8U (I think
Belden.) from the AH4 to the radio. You are correct about the AH4 being
designed to tune a wire against ground, but this loop works fine. In the
past, I also rigged up a dipole to the ah4 (450ohm ladder line (+ & -) to
the dipole feedpoint) and it worked well too. It's a very nice tuner
(coupler).

73
Smitty -kb3gun