Hi Bob,
One thing I forgot to check before and I pretty sure I found out what
the problem is. I have the PC soundcard out connected to the audio in
on the back of the radio so I can use it for digital modes. Seems as
though it's picking up hash from the PC and it's getting mixed with the
audio from the mic. When I disconnect the cable from the PC, things are
normal. Dang it! Guess I need to put another or more ferrite cores on
the audio cable. I hear the computer hash when I test PTT with WSJT-X
too. So it's transmitting a cruddy digital signal too. That's
unacceptable. I have to fix that.
73
Stan
KM4HQE
On 9/17/2018 8:51 PM, Bob McGraw K4TAX wrote:
Stan:
First I suggest turning the speech processor OFF and forever leave it
OFF. If you want to use it, just remember, more is worse.
Even though the mikes worked on the TR7, I view this is no indication
the wiring is correct for the Omni VI. I suggest checking the manual
for the correct mike wiring and physically confirm the mike of choice
is wired correctly. I find mike wiring standards to be as varied as
dust particles in a Texas sandstorm.
Pin #1 is mike high or mike audio
Pin #2 is ground and shield. Be sure the shield of the mike cable
also folds back into the Amphenol cable connector to make contact with
the shell.
Pin #3 is PTT
Pin #4 is +4 DCV for use with an Electrect mike.
Check the plug in filters on the bottom to see they are seated
correctly and correct location. Again, contact cleaning of their pins
might be in order.
One other test, disconnect the mike, turn the MIC gain fully
counterclockwise {off}, transmit and listen to the radio. With the
2nd receiver, tune across the frequency and listen for carrier. In
general all should be quiet. If you hear significant carrier, there
is a procedure to null the carrier. Probably need an oscilloscope and
dummy load to do that.
Next would be to check the frequency of the BFO crystals. Again there
is an alignment procedure. This must be adjusted in the exact steps
outlined in the manual as there is interaction between the
adjustments. Repeat the procedure a couple of times. A frequency
counter is required for this adjustment. Don't skip one step just
because you don't intend to use that mode. There is interaction
between the adjustments.
And of course my last suggestion, which normally is my first
suggestion..........take time to pull each cable, using a Q-Tip
moistened with contact cleaner, scrub the male pins of each and every
connector. Then plug and unplug the connector a couple of times so
as to wipe the female contacts. Do this one at a time and double check
to see each connector is inserted fully and correctly.
NEVER NEVER NEVER spray anything into the radio. {One fellow I know
[not me] removed the plugin IC's, sprayed into their sockets, and now
he has a radio full of issues and weirdness. Remember contact
cleaner is used to promote the flow of current. Imagine what takes
place in a logic IC socket that is wet with cleaner. ugh!!!! }
With a radio of that age, it not at all unusual for the electrolytic
caps in the audio stage to deteriorate. One issue which can exist is
the output of a stage can drift negative a few millivolts. In effect
it will reverse polarize the coupling capacitor. The result is after
time the 1 MFD cap will migrate to about 0.01 MFD. Not a good path
for audio in these circuits. Makes the radio sound funny too. I
always replace the audio coupling capacitors with nonpolar
electrolytics of the same voltage and C value. There is no need to
change parameters. Problem solved. I had a lengthy discussion with
Tentec management and engineering on the subject some years ago. It
almost caused me to not buy a new Omni VI Plus. Finally, I did and
loved it.
Hope this helps.
73
Bob, K4TAX
On 9/17/2018 8:00 PM, Stan Gammons wrote:
Hi All,
I was tinkering with an old D-104 T-UG8 that I had put a Heil
conversion kit in since the original element bit the dust. I ask for
an audio report from some of the locals that know what I sound like
and they said I sounded terrible. So, I switched to the Ten-Tec 707
mic, same report. So, I tried my trusty old EV-638. Same story. I
didn't try it with the converted D-104 to see what it sounds like.
They initially told me it sounded like the mic was picking up
something like a fan maybe, so turning the gain down helped a little
but not a lot. SO, today I decided to put the Omni VI on a dummy load
and listen to it with my Drake TR7. Yuck! The Omni VI sounds
terrible! It's almost like there is a little bit of a carrier and it
has what sounds like digital hash on it. It gets worse the higher the
mic gain is cranked. When I modulate, the audio sounds all distorted.
Even without modulation, if I turn the processor on and crank it up,
the digital hash in the audio seems to get even worse. SO, just to
make sure it wasn't something weird going on, I did the same thing
with the TR7. I put it on a dummy load and listened to it with the
Omni VI. I tried it with the same mics and the audio is clean. No
hash or anything. Anyone heard of a problem like this with an Omni VI?
73
Stan
KM4HQE
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|