[Hallicrafters] SX-62 500kHz crystal

[Mike Everette]

If you need a 500 KHz crystal, the FT-241 crystal
which is marked "Channel 70, 27.0 MC" has a
fundamental of exactly 500.000 KHz.

JAN Crystals in Fort Myers, FL is a possible source of
these.  Their catalog, years ago, had a diagram of an
oscillator that worked with the FT-241 crystals.  I
think it takes a high amount of feedback to make them
work.  

Fair Radio Sales in Lima, OH might be another source.

If you order one of these crystals, get TWO -- just in
case the first one is bad.  The holder's pins are
connected to the actual quartz crystal via fine wires
that are soldered to the electrodes attached to the
quartz.  I have encountered a few wherein the solder
joints have broken loose.  Resoldering them would be
possible, but very dicey.

These are very high-accuracy, temperature-stable
crystals.

In the original circuit, these crystals were 1/54 of
the operating frequency for the BC-604 transmitter, a
radio commonly used in WW2 US tanks and other armored
vehicles.  The oscillator tube was somewhat analogous
to a 6L6, but had an instant-heat filament.

Whether it would work in the calibrator for the SX-62
is problematic, but worth a try.

73

Mike
WA4DLF

--- "M. Ross Dumke" <n5tde at earthlink.net> wrote:

> U.S. crystal used to be located in Fort Worth, TX,
> Peterson I believe is
> still in Council Bluffs Iowa and still in business
> (2-3 years ago) and a
> firm in Florida, can't recall. First suggestion:
> Internet. 73's N5TDE
> 
> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net]On
> Behalf Of Julian Bunn
> Sent: Friday, March 31, 2006 12:42 AM
> To: hallicrafters at mailman.qth.net
> Subject: [Hallicrafters] SX-62 500kHz crystal
> 
> 
> The crystal marker in my SX62 wasn't working. After
> substituting a
> crystal of different
> resonant frequency, and finding that the 6C4-based
> oscillator worked, I
> pinned it
> down to the installed crystal itself being faulty.
> 
> I carefully took the case off it, and inside found
> that one of the
> contacts had separated
> from the thin sliver of crystal. It was very fiddly,
> but I managed to
> resolder it back on.
> However, the crystal still doesn't work.
> 
> Anybody have any advice: is this likely to be
> repairable, or do I need
> to find another
> crystal? If the latter, where would I find a 500kHz
> crystal for sale?
> 
> Thanks!
> Julian
>
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