[time-nuts] FE-5680A won't lock

Robert Benward rbenward at verizon.net
Wed Jan 18 16:00:50 EST 2012

It would be interesting to see if you can remotely mount the Rb lamp.  The 
high temps certainly do nothing for the long term reliability of the 
electronics.  A fan is a good start.


----- Original Message ----- 
From: "Peter Gottlieb" <nerd at verizon.net>
To: <time-nuts at febo.com>
Sent: Wednesday, January 18, 2012 11:22 AM
Subject: Re: [time-nuts] FE-5680A won't lock

>   IMHO these units are designed for cooling by airflow around them and
>   minimal conduction cooling.  With my unit there is minimal heat flow
>   from the unit to the PC board it came attached to.  I am going to
>   simply cut down the board a bit and mount it in a small plenum made of
>   FR4 and use a small fan with controller.  This will be simple and get
>   heat out from all sides.  It should be the closest to the way it was
>   intended to be cooled, improved with the temp control, and still be
>   small enough to be placed into other equipment.
>   On 01/18/12, J. L. Trantham<jltran at att.net> wrote:
>   Use one of your 'locked' Rb as the 'standard' and then look at the 10
>   MHz
>   from the 'problem child'. See if you can adjust C217 (I think. Look at
>   the
>   archive.) to bring the 10 MHz signal close to the 'standard'.
>   Perhaps the oscillator is just out of 'range' and can be brought back
>   into
>   range where the loop can lock it. Or maybe that is what you have
>   already
>   done.
>   Both of my units get quite 'toasty'.
>   Joe
>   -----Original Message-----
>   From: [1]time-nuts-bounces at febo.com
>   [[2]mailto:time-nuts-bounces at febo.com] On
>   Behalf Of Scott Newell
>   Sent: Tuesday, January 17, 2012 10:31 PM
>   To: [3]time-nuts at febo.com
>   Subject: [time-nuts] FE-5680A won't lock
>   Just got my 3 in from nichegeek. Paid Thursday, shipped Friday,
>   arrived this evening. Wow. (Actually arrived too quickly--I don't
>   have my t-bolt running, so I can't easily do an accurate frequency
>   check.)
>   Two power up and lock in <3 minutes. One powers up, gets toasty, and
>   gives 10MHz, but no lock and no PPS.
>   The tuning config on all three read back as 0. I've set the problem
>   child to near +/- FS and about +/- 25% of tuning range: still no lock.
>   Any suggestions on what I should look for or try? I'm not quite
>   ready to throw in the towel and contact the seller.
>   --
>   newell N5TNL
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