[BC] Exciter PLL unlocks...

[DHultsman5@aol.com]

In a message dated 4/12/2007 1:14:21 AM Central Daylight Time,  
biwa at earthlink.net writes:

Is this  a recent problem?  Is it possible that the AFC is near the 
edge of  locking?  If that's the case then it might be a simple matter 
of  adjusting the FMO to bring the lock/AFC back to center.  How old 
and  what make and model exciter is it?

Burt



*********************************
 
Bert reminds me of a problem with the Collins 310Z2 Exciters.    After about 
3-4 years the reference frequency of the crystal would age.  As  it aged,  it 
would exceed the range of the AFC.  After this period of  time an extreme 
modulation peaks especially of low frequency or a power failure  would sometime 
cause the AFC to unlock.  It could be predicted by switching  off the AFC lock 
switch and see the AFC meter go high or low, it should stay  near the reference 
zero on the meter.
 
The simple soulution was to use the crystal adjust to set the reference  
frequency to the AFC zero point voltage.  Probably also could be done with  a 
counter to read the reference crystal frequency and set to the correct  frequency.
 
Dave
Continental Electronics



************************************** See what's free at http://www.aol.com.