An update: I suspected U302 on the TX exciter board is at fault for causing the radio to transmit when turned on (except in the 2.5/5 MHz bands). So I've mounted a new IC in a socket to make testing easier. Pin 6 (VOX circuit) is high at all times, so I physically isolate and ground this pin (pins 1 and 2 are high and low, so no issues there). Yet, U302 still enables the TX (pulls 3 and 5 to ground)! What madness is this?
Pulling U302 completely from the board enables receive on all bands (as would be expected). Plug it back in (sans pin 6), transmit on all ham bands, all the time. I'm officially perplexed. Is there some other means by which the radio can be put into transmit mode independent of U302? That's the only other logical explanation I can fathom. --Brian/WA3ITE _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
