On May 13, 2:07 am, Richard Clark wrote:

The way you described it (presuming an efficient choking BalUn) with
battery operation and you remote from it, suggests any issue of
"unbalance" is strictly academic. You can force it to become a real
problem if the case of the 259 is close to ground where the chassis
adds a capacitance to ground, but that is a rapidly diminishing value
as you raise it (couldn't be more than 1 or 2 pF at 6 feet up).

Richard, I tired measurements again with my twin lead directly
terminated to the 259b. I got better, more consistent results after
taking great care to insure the analyzer and line were well isolated
from ground, other conductors, and myself. I then took the same
measurements with the 4:1 balun between the twin lead and the
analyzer. Unfortunately the results create new concerns. For example
at 7.185 Mhz with the balun in the circuit (tuner in bypass mode) I
got 19 -j48. Again at 7.185 Mhz with the balun out (twin lead directly
terminated to 259b) I got 159 -j443. Doesn't look like 4:1 to me.
Similar spreads in the 80m and 20m bands.

This is extremely unlikely (being a current BalUn) unless it is
specifically specified as one (and even then, many professed 4:1
current BalUns are in fact no such thing).

The MFJ manual for the 993b tuner says the balun is a 4:1 "current"
balun. Haven't looked inside to confirm this.


You have the means to test the assertion, use your 259 to measure the
isolation of the BalUn. This was the subject of a recent thread.


Thanks. I'll search for the thread. Sounds like fun.

Wish I had a 1:1. At 7.185 Mhz
through the 4:1 balun (tuner bypassed) I get 19 -j48. Assuming an
ideal balun I believe your previous post stated this would be 76 -j192
on the high side. At most even harmonic frequencies I've measured, it
appears the 4:1 balun in the tuner is actually resulting in too low a
resistive term impedance.

Fixation on BalUns has clouded a simpler solution: wind a choke in
the line and dump the ferrites of suspect quality.

Would you please elaborate on this? Wind a choke where? In the twin
lead? In the short transmitter to tuner coax line?
Thought I read somewhere that only coax can be used for simple 8 to 10
turn chokes. Balanced lines (i believe because of mutual conductor
inductances) can't be coiled as chokes.


Many antennas work just fine until the operator discovers a new tool
that proves it doesn't (in spite of a wall full of QSL cards).

Partly the reason I'm trying to learn all I can about the
configuration I've currently got. That and I like the technology
aspects of the hobby as much or more than I do operating.

Thanks for helping out a Stuggling Crippled Newbie Street Urchin.

Wait until you face the sewer rats of Rio.

OK I'll bite. Who are the Rio rats?

Thanks for your help. Any thoughts on those measurement results
earlier in the post will sure be appreciated.

73's
Dykes Cupstid AD5VS