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

EWKehren at aol.com EWKehren at aol.com
Wed Jan 18 16:39:13 EST 2012

Looking at the unit I think a lot of thought went into the total design and 
 cost may have been the main driver, but overall performance is 
impressive.. It  would be nice to have some one tackle that approach, the ribbon cable 
will make  it easier but still some other elements will have to considered, 
like the two  transistors at the lamp side. I for one plan on taking it out 
of the case and  use a top and bottom plate integrated with a fan cooled 
plate totally surrounded  by foam and hold my back plate which is the long side 
at 45 C. Presently  running fan test to pick the right fan / heat sink 
assembly. More than any thing  else temperature control will determine overall 
performance and board  temperature below 50 C will help life.
Bert Kehren
In a message dated 1/18/2012 4:01:41 P.M. Eastern Standard Time,  
rbenward at verizon.net writes:

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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