[SignalOne] MilSpec 1030 repairs

[Bob Sullivan]

Listmates,

Since there have not been too many posts lately I thought I would describe troubleshooting efforts with my MilSpec1030 which I generally use daily. It's my all time favorite transceiver! During a recent RTTY contest the transmitter suddenly quit along with that "familiar" burning smell!

After removing the final amp/driver board and heatsink assembly I noted that one of the MRF421base resistors (10-ohm) was burned up. Hmmm … what caused that? Further investigation showed that one of the tabs on one of the MRF421's had never been soldered! (Sig/one QC practices?). Apparently it has been making contact and lots of heat due to RTTY ops caused it to open. I replaced both MRF421's with MRF422's. Tested but still no output. Found there was no RF drive.

Finally found that there was no T/R voltage on transmit. Checking the power supply board I (finally) noted that the RED LED (CR12) was not lighting on transmit (like it should). More troubleshooting found Q12 (2N2907) defective. Thankfully this transistor was socketed. This failure seems unrelated to the original problem but replacing Q12 corrected the T/R issue. RF drive now okay and output power back to normal.

These rigs are pretty but NOT easy to work on. This is not helped by the numerous manual errors. I wish S/1 had spent more time making sure the documentation was correct rather than gluing all those little photos at the beginning of each section! Hi.

73, Bob
WØYVA
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