[Elecraft] VOX clicks with Yaesu MD-100 microphone

[Stewart Baker]

Here's a good one...

While testing the latest version of my Anti-VOX board I got reports saying that 
my SSB signal was "clicky"on VOX. I thought the worst...

After much investigation it turned out to be nothing to do with my board, or the 
K2 for that matter.

Some "Engineer" decided when he designed the MD-100 microphone tone control 
circuitry to route the PTT line clean through the center of it's analog 
circuits.

The K2 uses the PTT line on VOX for TX/RX changeover. The effect I was getting 
was the low to high transition at the end of the VOX delay period being coupled 
into the microphone audio, causing a "click".

The solution was simple. I removed the PTT wires where they connect to the main 
PCB in the microphone base, and reconnected them separately. End of problem. 
It is possible that other microphones may be similarly afflicted.
If anyone wants more detail, please shout. 

73

Stewart G3RXQ

B.T.W Version 3 of the Anti-VOX is working well.