[time-nuts] How I got my FE-5680A to lock in Sydney, Australia

Jamieson (Jim) Rowe jimrowe at optusnet.com.au
Sat Feb 8 20:57:47 EST 2014

Hi Magnus,

Thanks again for those further suggestions. I do have a GPSDO, and I had 
been able to use it with a counter to check that the FE-5680A was swinging 
either side of 10MHz. But I didn't make sure that it was swinging evenly 
each side of 10MHz . According to my notes it was swinging between  9.999770 
and 10.000036MHz -- i.e., about 230Hz low and about 36Hz high. But it was 
spending more of the time below 10MHz than above -- does this suggest to you 
that I should tweak C217 until it swings by about the same amount either 



-----Original Message----- 
From: Magnus Danielson
Sent: Sunday, February 09, 2014 3:36 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia

Hi Jim,

On 07/02/14 05:19, Jamieson (Jim) Rowe wrote:
> Hi Magnus,
> Thanks for those suggestions also. So if I understand you right, I'd be
> better off trying to tweak the oscillator tuning -- using the trimcap?
> Or did you mean via the RS-232C 'offset adjustment' command?

I covered this in another message I just sent, but for completeness:

You want the C217 trim-cap adjusted such that the lock-in sweep will
sweep over 10 MHz, because that's where the synthesized magic locks up
and you get 10 MHz out.

If you use the offset adjustment, you could possibly get it to lock up,
but not producing the 10 MHz you expect.

Once you got the trick, it's actually quite fun to trim and get the warm
fuzzy feeling of fixing it as it locks up.

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