More info, Richard:

I climbed up on my roof last night (from my 3rd floor balcony - always an
adventure!) with a flashlight to check my RF ground - sure enough the old
cable had a splice that was broken in one place (that I could find in the
dark). So I fixed that. I also verified that the internal fuse of my radio
(IC-706) wasn't blown (the tuner connector on the back of the radio still
put out +13.8Vdc.

When I plugged everything back in, I figured I'd at least be able to tune at
least a couple of the bands, but I was met with - nothing. Pressing the Tune
button on the radio for two seconds would do absolutely nothing - no
changing mode to CW and keying for transmit, not even a short beep saying
the tuner couldn't tune the long wire. Just dead.

By then my wife was dragging me out for dinner, and it was too late after
for any troubleshooting. And this weekend, I'll be out of town, so I won't
be able to do any serious troubleshooting during daylight hours for another
week and a half.

Man, this is frustrating...


"Jon KB1HTW" wrote in message
...
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...