[evlatests] ea08 synthesizer mystery

[Terry Cotter]

It is possible that the synthesizer has false locked. The synthesizer 
has frequency counters built-in and you can check the actual frequency 
the synthesizer is tuned to vs where you want it to be. You do this by 
turning the prescaler on in the synthesizer. The prescaler is normally 
left off because it generates RFI on the output. So, if you turn it on 
to check the frequency be sure you turn it off afterwards. If you happen 
to find the synthesizer is locked at the wrong frequency, we would like 
to know the frequency it is locked to, as well as the frequency you wanted.

Rick Perley wrote:
>     In my various observations at many frequencies at all the bands, 
> (using the VLA correlator) I often find antennas which give no fringes 
> on some observations.   It is usually the case that one IFpair is o.k., 
> and the other 'dead'.  At a later time, the 'dead' IFpair will spring 
> back to life -- only to be found to be 'dead' later on ...
> 
>     This sounds like what Ken is reporting below ...
> 
> 
> Ken Sowinski wrote:
>> While trying to do an L band Widar observation ea08 was incoherent.
>> Checking the usual antenna things, including synthesizers, found
>> nothing wrong.  Eventually we went back to the old correlator
>> and found that ea08 incoherent in AC, but fine in BD.  Both the
>> L301 and L302 claimed to be working and locked.  both were rebooted,
>> but still no fringes.  I then started going through the bands and
>> ea08 worked fine at C, S, X, and K bands.  Back to L band and all
>> was working again.
>>
>> Will anyone hazard a guess as to what is happening?  Or, what to
>> try if this should happen again.
>>
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