Thanks for the info, but I don't think it'll work.

From http://home.comcast.net/~hamlakemn/ah4/ah4.htm (great site for AH-4
info, by the way!)

"The AH-4 uses 12 volt inverted logic and an "open collector" transistor to
ground to perform signaling. The radio provides 13.8 volts to the tuner. It
also provides a START line that is pulled up to 13.8 volts inside the radio.
The radio pulls the START line to ground to assert the signal (start the
tuning operation). Similarly, the AH-4 pulls the KEY line to 5 volts through
a 22 kohm resistor/diode combination. The radio also pulls this line to 13.8
volts through a resistor. The AH-4 pulls this line to ground to assert the
signal (indicate tuning status to the radio.)."

I think it may be more effort than it's worth. Plus, I'm not sure if what I
described as the "problem" is really the cause - I just think it was the
most likely candidate. I guess I need to check the end of the cable and see
if I'm getting better than 12V at the tuner. The author of that website says
he's been able to control the tuner using 18 gauge rotor cable up to 60
meters away. My Cat 5 Ethernet cable is probably 24 or 26 gauge solid core -
that's why I paralleled the leads. Another possible cause why the tuner
can't tune any band is that my temporary ground is probably pretty poor. The
tuner's on the roof, feeding a long wire - 14 AWG copperweld, ~73' I just
tied the RF ground terminal on the tuner to an old 10 AWG aluminum lightning
ground wire that goes down to the electrical service entrance of my house.
The ground there is a cold water pipe augmented with an 8' length of 1/2"
copper pipe driven 6' into sandy/rocky ground.

Since the AH-4 is supposedly capable of driving a dipole - with the tuner at
the center, I think I'll try stringing up another wire as a counterpoise.
Only I don't have 150' linear feet of space on my property, so the dipole
will end up being a sort of a "J-pole" being fed at the center...

Good thing is that I live on a harbor in Massachusetts, so as soon as the
weather's better (like May? ;-( ), I should be able do drive some ground
rods next to the seawall, where they'll be in sal****er-saturated sand.
Hopefully they'll last a few years... I'm itching to get my IC-706Mk2G up
and running HF - 2m/70cm works fine...


"Richard Clark" wrote in message
...
On Wed, 2 Feb 2005 15:09:14 -0500, "Jon KB1HTW"
wrote:

Which is the preferred
route for minimizing RFI or cable capacitance affecting the Start/Key
pulse
signals?

Hi Jon,

Use RS-422 components to translate voltage signals into current
signals, and then back (at the other end) to voltage signals. If you
have surplus twisted pairs, then this will give you the
transmission/length requirements.

73's
Richard Clark, KB7QHC