Run both audio sources in the back. Switch between them with a conveniently
mounted DPDT switch. These rigs ain’t worth much any more. I little hole, or a
bracket added somewhere isn’t gonna kill what little value they have left. I
like mine, but have a few tinkerers mods slated for the upcoming winter months.
Kind regards,
Greg, KC8HXO
Sent from my Linux device
> On Sep 18, 2018, at 09:29, Bob McGraw K4TAX <rmcgraw@blomand.net> wrote:
>
> Even with that approach, any noise coming out of the computer sound card
> output stage will be sent to the input of the Omni VI. This will occur even
> when the audio gain of the computer is reduced or muted as the gain control
> is before the output stage of the sound card. Just the fact, any noise
> coming out of the computer will be introduced into the MIC audio due to the
> design of the circuit.
>
> One can add some 20 dB of attenuation in the form of an L Pad between the
> output of the computer and the input to the radio. This will reduce the
> amount of noise to perhaps a satisfactory level. But still, there will be
> some noise coming from the computer sound care, reduced 20 dB. And one will
> then need to raise the gain of the data signal in the computer application to
> off-set this 20 dB attenuation. While I find this works and I operated this
> way for years, the digital artifacts from the computer may still exist to
> some lesser extent, although may be found to be satisfactory.
>
> The best solution is to disconnect the cable to the rear input when not used.
> But when used, you will still likely need the 20 dB attenuation to clean up
> the digital noise out of the computer. A Transformer is an OK idea as long
> as it is configured to have voltage loss and not matched loss. The idea of
> the transformer is to eliminate a "ground loop" what ever that might be.
> {The only ground loop I'm familiar with is upon less than a careful landing
> of a Piper Tripacer in a cross wind.}
>
> 73
>
> Bob, K4TAX
>
>
>> On 9/18/2018 4:50 AM, Barry N1EU wrote:
>> Stan, to get rid of the residual hash do one of the following:
>>
>> 1. assure you have the computer chassis and Omni 6 chassis properly bonded
>> to common station ground.
>> 2. put an audio isolation transformer in the line between PC soundcard and
>> Omni 6 audio in
>>
>> 73, Barry N1EU
>>
>>> On Tue, Sep 18, 2018 at 2:41 AM, Stan Gammons <s_gammons@charter.net> wrote:
>>>
>>> Hi Bob,
>>>
>>> I removed the split core I had on the audio cable and put a solid core
>>> with several turns of the the audio cable wrapped around the core at the
>>> sound card output. That drastically reduced the hash picked up from the
>>> PC. So, it should have a MUCH cleaner digital signal now. Now when I
>>> remove the mic and short pin 3 to ground and turn the mic gain fully
>>> clockwise, the rig is putting out maybe 1 watt. Much better than the 100
>>> watts it was putting out when I tried the same thing before! Yeah, it is a
>>> bummer that both are hot all the time. I'll have to remember to
>>> disconnect the cable from the PC when operating phone. Would have been
>>> nice if one were able to select the audio source.
>>>
>>> Thanks for your help. Hopefully I'll sound better when I check into the
>>> net now :)
>>>
>>> 73
>>>
>>> Stan
>>> KM4HQE
>>>
>>>
>>>
>>>> On 9/17/2018 9:25 PM, Bob McGraw K4TAX wrote:
>>>>
>>>> Stan
>>>> Unfortunately that input on the rear is "hot" all of the time and the
>>>> signal (noise) is mixed with mike audio. It is isolated by a 10k ohm
>>>> resistor. The MIC gain and SP level controls both inputs.
>>>>
>>>> You must physically connect one or the other, but never both. There is no
>>>> provision in the radio to select between the two inputs.
>>>>
>>>> I wouldn't bother with chokes as any noise from the computer or interface
>>>> will appear in mike audio. Just the way it works. Bummer.
>>>>
>>>>
>>>>
>>>> Bob, K4TAX
>>>>
>>>>
>>>> Sent from my iPhone
>>>>
>>>>> On Sep 17, 2018, at 9:16 PM, Stan Gammons <s_gammons@charter.net> wrote:
>>>>> 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 wo
>>>>>>>
>>>>>> rse. 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
>>>>>>>
>>>>>>> _______________________________________________
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