Dead Receive on Maxtrac

RadioWadd · Post by **RadioWadd** » Tue Feb 28, 2006 2:37 pm

I have two Maxtrac radios and both are deaf as a post on receive. They transmit great but there's no receive at all. One is a VHF 5 pin and the UHF is a 16 pin. I can use the Mon. and hear speaker noise on both. Do the receive on these radios just die completely? Any help would help.

Post by **wavetar** » Tue Feb 28, 2006 2:54 pm

It is VERY likely that the 1st oscillator crystal (44.645MHz, I believe?) is dead. That's by far the most common culprit for no RX in the Maxtrac/GM series radios. Usually if it's a bad 45.1MHz 1st I.F. filter, or a bad 455KHz 2nd I.F. filter, you can get it to receive something if you pump enough signal into it. It can also be a couple of blown diodes in the receiver front end, but I wouldn't classify that as a common problem.

Todd

richb · Post by **richb** » Tue Feb 28, 2006 7:21 pm

I agree thats the the problem , one way to test is if you have a way of generating the 2nd osc freq, set it to the 2nd osc freq and radiate it near the bad radio and if the radio starts to rec then the xtal is bad. Ive done this all the time and it works, also you might want to see if the rec vco is locked. check pin 5 on the interconnicting jack that connects the logic bd to the rf bd and see if the voltage is around .1 to .2 volts in rec mode. The vcos dont go out of lock very often but sometimes they do.

Thanks
Richb