[time-nuts] troubleshooting a FE-5680A (got two; only one works)

WB6BNQ wb6bnq at cox.net
Wed Nov 30 04:26:28 EST 2011


Instead of trying to fix it you should fault the unit back to seller and get a refund or have him
send another unit.  I would also attempt to get them to pay for the return shipping as well.  After
all it is their fault they sent a bad one when all of them are claiming that they are working

As for troubleshooting, that is way easier said then done.  These newer series of FE-5680's are much
more digital in nature then the older design, which makes it much harder.  The company that makes
them is not and will not give out information.


John Beale wrote:

> 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
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