This is an update on the TR-7 that I recently purchased on eBay and promptly
blew up in the course of testing.
After inadvertently transmitting into the RX input, I found the diodes in the
CM-1 mixer module shorted and ordered a replacement MiniCircuits SBL-1MH from
RF Parts in CA.
My choice of this part was based on comments provided on this list and what was
available from RF Parts. I may want to look at other options further down the
road, but my goal was to get the radio working again as quickly as possible.
The part arrived yesterday, and with thoughts of a possible long battle with an
endless string of problems, I installed the replacement on the upconverter
board and re-soldered the shield to the module. I also re-soldered a number of
questionable-looking areas on the upconverter board and cleaned up a lot of
flux that had been left behind in the manufacturing process.
After another hour of carefully re-installing the parts removed to get to the
problem, I was ready to power up the radio, although the I did not replace the
cabinet cover.
I connected my OCF dipole that I use for general receiving, clicked the power
on, and was rewarded by the blissful sound of HF noise! Quickly tuning through
the 40m band proved that the RX was working -- at least as well as before my
little mishap.
I would like to thank all who posted comments to my original message -- this is
a list is a goldmine of information, and I am humbled by the depth of technical
knowledge available.
Now on to the TX problem ...
Regards,
Charles
K5QED
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