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

[Jamieson (Jim) Rowe]

Hi Charles,

Sorry, but I didn't accidentally transpose the 'high' swing numbers. That's 
why I was so confused about the results.

The counter I'm using is one that I designed myself. As an alternative to 
its internal 1MHz XCO timebase (with dividers down to 1Hz, 0.1Hz etc), it 
also allows you to use an external source of 1Hz pulses like those from a 
GPS receiver or a GPSDO, or a Rb Freq Reference. The dividers operate on 
these 1Hz/1pps pulses as well, to provide gating times of 1s, 10s, 100s or 
1000s. It seems to work pretty well.

Cheers,
Jim Rowe


-----Original Message----- 
From: Charles Steinmetz
Sent: Monday, February 10, 2014 3:37 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] How I got my FE-5680A to lock in Sydney, Australia

Jim wrote:

>Here's what I found, as before looking at the frequency with my counter 
>(GPSDXO 1pps timebase):
>
>Inverted position:  swings between 9,999,798Hz and 10,000,001Hz, before 
>locking.
>Normal position:   swings between 9,999,756Hz and 10,000,057Hz, a few 
>times.

Are you sure you didn't transpose the "high" swing numbers?  As you
state it above, the oscillator swings 203 Hz (peak-to-peak) when
inverted and 301 Hz p-p right-side-up.  If we swap the "high" swing
numbers, it is 245 Hz inverted and 259 Hz right-side-up, which seems
more plausible.  There seems to be little reason why the absolute
value of the sweep range would vary so much (203 to 301).  Also, a
normal range of 9,999,756 to 10,000,001 and an inverted range of
9,999,798 to 10,000,057 would seem to explain your previous results,
while the results reported above would not.

I'm a little confused by what you've said about your counter time
base -- as I recall, you said you were feeding GPS 1pps to the
counter.  I'm not familiar with any counter that locks to 1pps -- 
most counters I'm familiar with lock to 10MHz (or in older gear, 5MHz
or 1MHz).  Can you say a bit more about your "1pps timebase"?

Best regards,

Charles



_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.