[Boatanchors] RX Muting

[Tom Norris]

Yep, when in doubt, use a relay to disconnect the high end of the volume control (and ground the "hanging" end) or bias bias one of the low audio stages to full "off."  A clamp tube could be used to rather than a relay to change the bias.  Could even get fancy and use a dual triode to open the audio path between the audio driver while bringing the tube input level "low" - I've seen several full-breakin circuits in the past that did just that.  A relay at the RF input that goes to ground on "mute" is a plus as well.  Non-purists can use high voltage MOSFETs for the audio switches, with a very slight fade factor to prevent popping during switching, similar to the method used by some broadcast consoles. (older consoles used tubes, optoisolators, relays, gnomes, etc) Of course, the least complex, the better - as always.

I have at least a couple of examples that I could send if anyone is interested.

Tom NU4G

On 7 Apr, 2011, at 11:34 AM, Wilson Lamb wrote:

> Don't leave the ouput xfmr open to mute the RX...asking for HV breakdown on primary...
> WL 
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