[WriteLog] Re: SSB Messages Bleeding into Headphones

[Dennis Mowers <k5ya@gvtc.com>]

All OK now--The solution was simple, but I still haven't figured out 
what kind of ground problem I have.

The tip off, as some suggested, was the low level hum in the audio.  The 
cure for hum in the audio seems to always be the 1:1 Radio Shack 
isolation transformer.

Interstingly, I only need one transformer.  It can either be placed in 
line with the left radio headset connection to the Keyer, or in the 
right radio headset line to the Keyer.  Not a trace of coupling now, and 
also some slight pops in the CW messages are also gone.

73, Dennis


Dennis Mowers wrote:

> I'm using a W5XD keyer for my headphone connection.  Radios are TS-850's.
>
> My recorded messages from the soundcard are getting into the headphone 
> path somehow.  The sound is very muffled, and hard to understand, but 
> loud enough to cover up a weak signal caller.  It happens on the 
> transmitting radio audio, or the same level on the 2nd radio audio 
> when I'm in the latched headphone position.
> I have the normal MIC to rig connections, via the soundcard, using 
> isolation transformers on the sound card output.
>
> Looking at the Keyer schematic, the headphone audio is switched with 
> relays, and there is no apparent  connection with the soundcard.  The 
> headphone connections have been moved several feet away from the mic 
> in/out wires, and that doesn't help.
>
> The only other thing that is not quite normal is a very low level 60 
> Hz hum in the headphones when the rig is switched to transmit.  I have 
> removed the PTT outputs from the Keyer to the radios, and used VOX, 
> and still get the hum when the VOX triggers the radios.
> It's not RF, because I have the rig power and  carrier levels turned 
> all the way down.
> If I go to the Keyer, unplug a headphone input and headphone output, 
> and connect them with a short jumper, removing the Keyer grounds and 
> internal relay from the picture, the problem  goes away.
>
> Has anyone had a similar problem?  What should I try next?
>
> 73, Dennis - K5YA

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