An updated update: My TR-7 now receives in all bands, thanks to a replacement TX exciter board that was silencing the receiver. (I still can't figure out how an AND gate can go high with only one input high, but that's an investigation for another day.)
Thanks for the assistance! There is another problem, though...I'll post this to a new thread. --Brian/WA3ITE On Thu, Jul 15, 2010 at 10:08:48PM -0500, Brian Koontz wrote: > 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. _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
