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

EB4APL eb4apl at cembreros.jazztel.es
Sat Feb 8 21:30:17 EST 2014


Jim,

According to my log, my first unit sweeps from  9.999766 to 10.000056 
and locks in less than 3 min.
My second unit sweeps from  9.9997414 to10.0000493 and also locks in 
less than 3 min.
Probably your unit needs to go a little bit higher.  The time spent at 
the limits probably is not relevant, I also noticed it and that they 
lock when reaching 10.0 MHz in the same ramp, I don't remember if going 
up or down.
But now that you are able to measure, what are the figures with the unit 
turned up and down?

Regards,
Ignacio EB4APL

On 09/02/2014 2:57, Jamieson (Jim) Rowe wrote:
> 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 way?
>
> Cheers,
>
> Jim
>
>
> -----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.
>
> Cheers,
> Magnus
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