Just yesterday I received two FE-5680A units from China. One of them works
and one doesn't achieve lock. Both are labelled with FEI P/N
217400-30352-1. Here's a photo of the one that works, the other looks just
the same but different serial number.
https://picasaweb.google.com/109928236040342205185/FE5680A#5680473663653140162
FE-5680A Rb #1:
At startup, RF out (pin 7) ramps from 9.999828 to 10.000066 MHz for a few
minutes, then locks at 10.000000 MHz and pin 3 drops low. The RF signal is
about 2 Vpp. Power draw at startup about 25 W, dropping to 10 W.
FE-5680A Rb #2:
RF out scans from 9.999799 to 9.999994 MHz repeatedly, and does not achieve
lock. Pin 3 remains high. The RF signal is about 1 Vpp (half the level of
the working unit). Power draw similar to unit #1.
Any suggestions for what might be done to prod the 2nd unit towards
working? I see some things which might be trimmer caps on the board, and
what might be a round heating element(?) soldered to a crystal can in this
photo:
https://picasaweb.google.com/lh/photo/0WRM10pGG0Kd89Ji80yoa9MTjNZETYmyPJy0liipFm0?feat=directlink
thanks for any advice!
John Beale
N8JUF
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