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Re: ubitx - purpose of relay contacts between Q70 and U1 (receive audio path)?

 

They are meant to cutoff the audio during TX. There has been some discussion on the RX pop fix and if you implement that then
this relay disconnection may not be required.

Emacs!

Raj, vu2zap

At 28-06-2017, you wrote:

I wish to understand the use of the relay contact pair (appears to be closed during receive) in the receive audio path between the first receive audio amplifier (Q70) and the audio power amplifier (U1). Is it to deal with leakage through Q70 during transmit (thinking the potential problem is mic audio getting into the audio power amplifier which appears to have very high gain), or is there another purpose behind the relay contacts in the path?

I ask this because I'm rendering part of ubitx into a PC board layout and am not otherwise using any relays (there is no transmit power amplifier section in my implementation), so I am considering alternatives to the relay (perhaps use a FET to ground the same junction during transmit?)

Thanks for any advice,

73 Dave WB0GAZ wb0gaz@...
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