Thanks to everyone for their suggestions! I don't have time to thank anyone
personally until after this weekend but I will early next week (and I'll
keep those off the reflector).
This reflector is an unbelievable resource... I'm overwhelmed by the number
of great responses I've seen.
I was able to get in touch with one of the service people at Ten Tec today
and mentioned my problem and that I had a pre-SMT Omni VI and I was
experiencing RF feedback problems. I asked if there was somewhere I could
install bypass capacitors or something similar to determine if it would
help.
He asked if my rig was connected to a computer and I replied yes. He
mentioned that the ground on the RS-232 serial connector sometimes caused
problems on the early Omni VI radios and he could send me a diagram on how
to make the changes to the TX Audio board or I could send the radio in. I
told him I wanted to run HP in CQWW this weekend and asked if he could fax
it to me.
A few minutes later the fax was in my hands and I could see the two traces
that needed to be cut but the fax was dark right where the new ground jumper
needed to be soldered so I called back and he explained the way the ground
traces run on the board and told me where to solder the jumper.
After the kids went to bed I took the rig apart, modified the board and just
connected the mic, the antenna (through the tuner), the power supply, and
the PTT switch. I then tuned 20 meters and worked HC8L (2nd call) at 1 kw,
asking him if my audio sounded good since I had been fighting RF problems.
He replied it sounded fine.
I then connected the RS-232 serial port jack to the computer and worked
K4QFF/TI8 (1st call) and he also said my audio sounded fine.
After that I connected the 1/8" serial port to the Fluidmotion antenna
controller to the rig and worked 6F1LM asking him for an audio check. He
thought my audio was a little harsh (no processor on) so I turned down the
mic gain a little (now at 8 o'clock) and he said it sounded great. I'm using
a Heil headset with the DX element.
I had disconnected the rig ground to the common ground point when I pulled
the radio out of it's space and just noticed it is not connected (I do
realize it's still grounded through the hardline shield). After reading the
suggestions I realized I had a cheap RS Field Strength / SWR meter in a
cardboard box somewhere in the garage and dug it out. I tuned up the amp at
1.5 KW and set it next to the radio. I heard TI5/N6JRL so gave him a call,
the needle barely moved on the Field Strength meter. I asked about my audio
and he said it sounded fine. I moved down 15 and pushed the tune button for
a few seconds and the meter read approx .25 (1-5 scale). I placed the meter
on the amp and it read .75, 3.0 on top of the wattmeter (Navy URM-203 made
by Struthers, uses Bird elements also), needle barely moved on top of the
amp power supply, and finally I put the meter next to the common ground
point and it read 1.75.
For now I'm declaring this good enough to get on the CQWW this weekend.
I'm definitely going to try some of the suggestions after this weekend. If
I can't get all the bands working up here I can take over a corner of the
laundry room in the basement. I would be able to be 30 feet away from the
tower horizontally and a floor lower. I can also drill a hole through the
concrete and pound a ground rod through the basement floor as well as
bringing a much shorter ground through the wall.
Thanks again for all the great help!
I'll keep everyone posted after I get more testing done and clean audio
reports 80-10!!!
George / KF9YR
|