[Milsurplus] FT-241 crystals question

[John Vendely]

In addition to the SSB crystal filters, some people used the 500 kc 
channel 70 or channel 360 crystals in crystal calibrators.  At least one 
receiver manufacturer, Pierson Radio, used these surplus crystals for 
this purpose.  I have a Pierson KP-81 receiver, built in 1947, with the 
channel 27 FT-241 crystal in its calibrator. The crystal is still good 
and as close to frequency as it was designed to be.

73,

John K9WT

On 1/11/2026 1:52 PM, Dave Merrill wrote:
> Aside from the few frequencies around 455kHz that were adapted for 
> sideband filters, what utility did any of the FT-241s have beyond 
> their original military use?
>
> --... ...-- Dave N9ZC
>
>
> On Sat, Jan 10, 2026 at 5:58 PM hwhall--- via Milsurplus 
> <milsurplus at mailman.qth.net> wrote:
>
>     They are spiffy-looking though. :-)
>
>     Wayne
>     WB4OGM
>
>     On Saturday, January 10, 2026 at 04:29:59 PM MST, John Vendely
>     <jvendely at cfl.rr.com> wrote:
>
>     Back in the late 60s, Esse Radio in Indianapolis had bins full of
>     FT-241s for a dime each, and in those days, it was rare to find a
>     bad one.  It's true that today, a good 50% of them have failed. 
>     Some have obvious problems like detached or corroded bond wires,
>     whereas the quartz elements of others seem to have mysteriously
>     lost "activity".  A few years ago a couple of us decided to fire
>     up the old SCR-508s and 608s.  Just for a laff, I tried opening
>     some failed FT-241s, and if they were mechanically intact,
>     ultrasonically cleaned them.  To my surprise, some came back to
>     life.  Occasionally, you can still find individual FT-241As in
>     sealed foil bags, and these have a much lower failure rate.  In
>     any case, other than for use in the original radios, the FT-241
>     has essentially no utility today.
>
>     The FT-241 was an unusually difficult crystal to produce,
>     requiring state of the art techniques.  There were multiple
>     attempts at setting up second-source FT-241 manufacturers, but
>     none succeeded.  Only its developer, Western Electric, was ever
>     able to mass produce FT-241s.  An FT-241 production line was built
>     at ITT which showed some promise, but the war ended before it
>     produced usable crystals in quantity, and the effort was terminated.
>
>     For the truly hard-core who really appreciate this stuff, there's
>     a very interesting and lengthy chapter with detailed technical
>     info on Western Electric's complex FT-241 production process in
>     the book "Quartz Crystals for Electrical Circuits" by Heising.
>
>     73,
>
>     John K9WT
>
>     On 1/10/2026 3:41 PM, Hubert Miller wrote:
>
>     >
>     These FT-241 LF rocks have a fail rate somewhere between 40 and
>     70%. Seeing that myself, dissuaded me from keeping any of them. I
>     believe the only people who might want them are the vehicle
>     militaria collectors.
>
>     I have not myself seen any article on how to bring them back.
>     Maybe two tiny pressure point contacts, that might get some
>     resonant activity, but there's no longterm fix i know of.
>
>     The 'Boatanchors' ham radio group a decade or so back, had a mass
>     dispersal of an FT-241 lot someone had found. Known as "The Great
>     Crystal Caper". I was sobered by the miserable results testing the
>     crystals, and i wrote off keeping any of those series.
>
>     -Hue Miller
>     ______________________________________________________________
>     Milsurplus mailing list
>     Home: http://mailman.qth.net/mailman/listinfo/milsurplus
>     Help: http://mailman.qth.net/mmfaq.htm
>     Post: mailto:Milsurplus at mailman.qth.net
>
>     This list hosted by: http://www.qsl.net
>     Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> Milsurplus mailing list
> Home:http://mailman.qth.net/mailman/listinfo/milsurplus
> Help:http://mailman.qth.net/mmfaq.htm
> Post:mailto:Milsurplus at mailman.qth.net
>
> This list hosted by:http://www.qsl.net
> Please help support this email list:http://www.qsl.net/donate.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20260111/c2a0f4dc/attachment.html>