At the end of the year my BITX transmitter section "broke." My BITX40 would not switch to transmit, and it simply continued in the receive mode, slightly shifting frequency. I thought I had blown the final. I made it the practice to not switch off the transceiver at night, to reduce frequency shift when it powering up the next day. I had no muting function and then thought the relay K1 was bad. If you run your radio via a dry cell battery keep in mind that if the battery's voltage drops too low, the relay coil in K1 might not switch when you switch to PTT (transmit). Happily, I realized that the voltage checks of 6.50 volts on the relay were what might be causing my problem. When I put a fully charged dry cell at 12v on the BITX40 it worked like it should. Simple issue, but one I did not think of first, so I wanted to share if you find that you cannot mute your transceiver when you switch to talk. It might be a simpler problem than you think .... In my case, simply a low battery! 73 - John - w4usf
