[Milsurplus] Odd choice of xtal frequency?

[Ian Wilson]

I have a Wilcox CW3 single-frequency aircraft monitoring receiver.
It has been slightly hammified - the "plug-in" coils have been replaced
by something else. Also, the original crystal unit has been replaced
by an FT-243 under the chassis, and the crystal coil has been replaced.

However, the original tube lineup is present, so this is still a
single-conversion
superhet with 455kc IF.

The crystal that is present is 6525kc. This doesn't make much sense to me,
since this puts the receiver on:
  - 6070 or 6980kc (xtal fundamental)
  - 12595 or 13505kc (second harmonic)
  - 19120 or 20030kc (third harmonic)

The receiver is only spec'd to work between 1950 and 16500kc but who knows.

Someone went to considerable trouble to do this, and made quite a neat
job that I am sure functions as they wanted it to. So what were they
monitoring?
Surely this wasn't intended to follow a converter; there would have been no
need to modify the unit at all in that case.

73, ian K3IMW
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20171026/5c3790e5/attachment.html>