[Hammarlund] SP-600 JLX-15 vlf rcvr - NOT!

[Glen Zook]

Remember that crystal control can use "high side"
injection at any of the fixed intermediate
frequencies.  For example, if one of the intermediate
frequencies is 455 KHz and you want to receive 18 KHz
then a crystal at 473 KHz would work fine.  

International Crystal makes replacement 455 KHz range
crystals for the Collins S-Line / KWM-2 series all the
time.

I believe that it was W7EKB, Kenneth Gordon, who made
the comment about the low frequency unit.  He is very
active on the Glowbugs reflector.

Every "crystal controlled" Super-Pro receiver that I
have ever seen just has the additional crystal
oscillator to allow better frequency stability on one
frequency.  Well, actually 2 frequencies since you can
use both low-side and high-side injection.

Glen, K9STH


--- "James A. (Andy) Moorer"
<jamminpower at earthlink.net> wrote:

It is very hard to make a crystal for anything below
about 400 kHz. They get quite large and easy to get
fractures and impurities. Any VLF receiver that has
slots for crystals is an exercize in wishful thinking.
Most crystal houses these days won't cut you a crystal
below about 700 kHz. JAN has cut me some 438 kHz and
472 kHz crystals to replace dead ones in a CV-591A,
but they did grumble about it (and charged me $3 each
more than their normal cost).









Glen, K9STH

Website:  http://k9sth.com

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