[Milsurplus] FT-241 crystals question

[Al Klase]

Dave,

You're right.  The crystal-lattice filters were the primary ham use.  
But, I did use a 518 KHz unit for a simulated Slaby-Arco alternator CW 
transmitter in a demo I built for our Museum https://rtm.njarc.org/ to 
give visitors a feel for what Sarnoff heard when Armstrong demo'ed his 
regen receiver at our site (Marconi Belmar, NJ) in 1914. VIDEO HERE 
<https://www.skywaves.ar88.net/VE-1.mp4>.

73,
AL

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
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-- 
ARK Sig Block Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/

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