forum.pistar.uk

Been playing with a MMDVM STM32-DVM, using an FT7800 for RF. It works fine with my CS750, CS800, MD380. and a Whistler scanner.
But for over 2 weeks, I cannot get my GD-77's to receive. Note the GD-77's, 4 of them, work fine with my other hot spots, DV4mMini, DV4AMBE, Shark
Openspot, and a Jumbo Spot. I have been going nuts, changing firmware, redoing CP's, searching the net.
For a reason that had nothing at all to do with this problem, I unscrewed the antenna on the GD-77. WALA the GD-77 starts receiving the 5 watt hot spot. Put the antenna back on and again no receive. FRONT END OVERLOAD TAKES OUT THE RECEIVER. The 5w hot spot is using a top side antenna.
Any Ideas?

if you have one of those RTL sticks, check what the wave form looks like from your radio, you may find that the signal isn't as clean as it could be, also when talking to a few other people, the 7800 tends not to be spot on frequency, FM can be quite a way out before its a problem, D-Star is also quite forgiving, DMR not so much...

i do have a rtl stick. ill check it out and see what i can find out.
thanks.

FIXED (I THINK)
Using a frequency counter, I found that the FT7800 was over 2kc low. Using the service manual, I saw that the PLL could be adjusted, via the face of the radio. once i had done the adjustment all radios were receiving.

FT7800 service manual

http://www.radioamatoripeligni.it/i6ibe ... t78001.pdf

see page E2

Nice work, watch for drift as the 7800 warms up too, you may need to over-cool it to keep it still...