A kit fix success story

 OK, not a kit but a transmitter with PK-4 keyer chip on-board (see QST, February 2014, A 10 meter beacon transmitter by Lou, W7JI).  This had worked for years as a beacon but recently stopped functioning.  Now although the PK-4 FB would be heard at powerup, it was impossible to enter any of the menus or even play a memory without halting.  I had thought that with the halting memory play that the problem was a bad momentary switch.  The ham with the PK-4 wanted new chips and I told him prior to the order that I didn't think replacement chips would help other than that they would establish that the problem was elsewhere.

It turned out that the 5V voltage regulator in the transmitter was bad.  When it was replaced the PK-4 menus and memory play resumed working again.

Which brings up my problem with diagnosing problems, I suspected the switch because it was a mechanical device, more likely to fail ?  I didn't even consider the regulator since the FB at powerup was heard.  But what pointed the ham to the fix was doing the simple voltage checks in this file:

http://wb9kzy.com/pk4diag.txt

Anyway, a success story !

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm