Ken Bessler wrote:


Now (finally!) to my questions:

1) How good are radio shack chokes?
2) I was only able to get 4 turns around the feedline's choke
- is that enough?
3) Am I just messing too much around trying to get a 40m
dipole to tune on 10m?
4) Would I do better to add a balun and run the 450 ohm
ladder line direct to the tuner?

--
73's es gd dx de Ken KG=D8WX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
VX-2R & FT-857

Hi Ken, I have had that problem with Auto tuners myself, and could not
get a satisfactory solution. The Vendors solution is Ferrite on the
coax, and make sure you have a good RF ground at the tuner.
The problem is almost certainly RF feedback getting into the tuner.
Since you have elimated current on the shield of the coax by the Radio
Shack cores (they should work, don't know of any recent studies of
these cores on 10m) that is not the problem.
The problem may be RF potential at the tuner by direct radiation. To
eliminate this you need a very good RF ground directly at the tuner.
For 10M this is a very short connection to a good earth ground. A 20'
long ground connection is not the answer.
You might try hooking a fan 10m dipole in parallel with the 40m
dipole. This would provide a better match for the Auto Tuner. If the
problem is still there, then it is direct radiation. Better RF ground,
or reduce power.
Gary N4AST