[Elecraft] Re: Amplifier T/R Keying problem - solved

[William Stewart]

I have received a suggestion from Don Wilhelm to install an RFC from the Rx
port to ground, and this solved the problem. 

 

Many thanks to Don for his advice and prompt response.

 

Bill Stewart, 

WU0R

 

  _____  

From: William Stewart [mailto:wkstewart41 at charter.net] 
Sent: Saturday, January 28, 2006 5:33 PM
To: 'elecraft at mailman.qth.net'
Subject: Amplifier T/R Keying problem

 

I have a problem trying to key a "homebrew" amplifier with my K2 (S/N 5251).
I am using the two-transistor T/R circuit from the "Mods" web page, and the
T/R relay pulls in as expected, however there is an annoying "thump" in the
received audio when the T/R returns to the receive state. I am using the
separate receive antenna (Rx) input. If I disconnect the receive antenna
line from the amp, there is no thump. If I trigger the T/R relay driver
circuit manually, there is no thump.  It seems that there is some
interaction between the receiver unmuting and the T/R relay going to the
"receive" state simultaneously that causes this thump. Any experience or
ideas?

 

Thanks,

 

Bill Stewart

WU0R