[time-nuts] FRK-H question

corby d dawson cdelect at juno.com
Thu Nov 22 12:53:07 EST 2007


It sound like your unit is locked.

Power it off for 15 minutes and then monitor the Xtal control when
powering back up.

It should sweep from about 2 volts to 15 volts.

Within 10 minutes it should stop sweeping indicating a lock.

After being locked for a few hours adjust the Xtal trim cap for around
8.5 VDC on the Xtal control pin.

It may lose lock while making the adjustment, just wait till it locks
again and continue until done.

Then after 24 hours you can adjust the C-field adjustment to set the
frequency against GPS or other known good <1X10-11th standard.

There are several options for the lock pin but try this:

Take a DVM (set on the ohms range that will source enough voltage to read
a diodes voltage drop) from the return to the lock pin. (+ volts from
ohmeter to lock pin) 

With the unit out of lock you should read an open, once locked it should
read a low value.

This is if your unit has the open collector output. If so an LED through
a dropping resistor to the +24VDC supply will give you a lock light!

Hope this helps!

Corby Dawson

More information about the time-nuts mailing list