[time-nuts] FE-5680A sweep range setting

Paul Berger phb.hfx at gmail.com
Sun Feb 23 22:47:25 EST 2014


Yes It took me several tries to find the spot, I only had success when I 
began only moving it in tiny increments I was not getting anywhere with 
1/4 or 1/8 turn adjustments, and you should leave it a few minutes on 
each try when mine finally did lock is started at a little over 10MHz 
and then dipped down 300 - 400 Hz below and wander around a bit down 
there, and I was ready to turn it off and tweak it again when it started 
back up and went across 10MHz and then it wandered back and forth across 
the 10MHz line before it finally locked.    I just ran across another 
reference to that C245 
http://www.febo.com/pipermail/time-nuts/2013-January/073442.html.


What I was referring to as the frequency control board does look like it 
would be mounted over the DB9 connector.  The two that I just got do not 
have this board installed on the  pictures link I posted it is at the 
center of IMGP2309_m and IMGP2310_m.  At 
http://ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq there 
is a short comment about this card under "Electronic Frequency Control 
(EFC)"  beyond that I do not know anything about the function of this card.

Paul.


On 2/23/14 6:01 PM, Simon Lyons wrote:
> OK ... I have C245 on the middle board, same as you. Tweaking it and ...
>
> Hmmm, it does affect the range (twitchy is an understatement!) but 
> still no lock. To be continued....
>
> Now by the 'frequency control board' do you mean the board that 
> overlaps the top of the D-Sub connector? I have been at a loss to 
> understand this section. There is all sorts of silicon on it but no 
> inputs of any kind. Just a 5V supply and a single analog output of 
> 1.99V on the orange wire. I'm baffled, so if you know what this board 
> is doing, please tell!
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