[time-nuts] time-nuts Digest, Vol 117, Issue 80

Mon Apr 21 17:30:52 UTC 2014

The FT-243 holders I revamped in the 1950s and 60s did have the aforementioned spring. However a close look at the electrode plates that contacted the quartz resonator had, in every case, a raised boss at each corner that spaced the center of the electrode a few mills above the center of the quartz. So the center part of the quartz was not restrained from moving. And it was not compressed by the spring.

As I recall the stack up was lower electrode, quartz resonator (square in the case of the FT-243) upper electrode, edge seal with hole for the spring, the spring, and then the cover.

I reworked quite a few of these at 8 MHz for use on the 2 meter band by multiplying by 18X. 8 x 18 = 144 MHz. Tooth paste moved them up and a small scratch with a bit of solder moved them down. 

Re: optically excite a quartz crystal? (Bob Camp)

 As for Bliley - go to the web site and if you look around, you can find a fascinating history of the company. It included details of the invention of the etch process and also of the "rubber rock" technique to vary the frequency of a crystal.

They still make some of the best resonators for custom designed oscillators around. I used them last in a synthesizer design for a FAA customer VHF/UHF receiver only about 6 years ago.

-73 john k6iql

-----Original Message-----
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To: time-nuts <time-nuts at febo.com>
Sent: Mon, Apr 21, 2014 11:00 am
Subject: time-nuts Digest, Vol 117, Issue 80

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Today's Topics:

   1. Re: optically excite a quartz crystal? (Bob Camp)
   2. Re: optically excite a quartz crystal? (Bob Camp)

----------------------------------------------------------------------

Message: 1
Date: Mon, 21 Apr 2014 11:24:43 -0400
From: Bob Camp <lists at rtty.us>
To: Poul-Henning Kamp <phk at phk.freebsd.dk>
Cc: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] optically excite a quartz crystal?
Message-ID: <402DEC2B-2405-493A-9866-31CC2CA8896F at rtty.us>
Content-Type: text/plain; charset=windows-1252

Hi

As with all ?good stories? there are many versions told by many people. I?ve 
heard far to many mutually contradictory versions to have any real idea what?s 
true. You are correct that etching was a known process in the 1930?s and that it 
had been used by various people at various times. Since it added time (and 
complexity) to the process, it got dropped by most people to speed up production 
?

Bob

On Apr 21, 2014, at 10:51 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> In message <A5032606-D7D7-4231-B1BD-434670274532 at rtty.us>, Bob Camp writes:
> 
>> Early in the WWII era, quartz blanks were not commonly etched after
>> begin ground / polished to frequency. This left debris on the surface
>> of the blank. The net result was that the resonators failed after
>> a period of time in the field, especially under damp conditions.
>> The problem got so bad that it actually threatened the ability to
>> communicate in 1942. A fairly high level team looked into the issue
>> and etching of blanks (and a few other mods) were made a mandatory
>> part of all crystals suppled to the government.
> 
> The story is slightly more interesting than that:
> 
> Blileys crystals were almost totally without these problems, but
> they wouldn't tell why that might be.
> 
> In the end the government put a lot of pressure on Bliley to squeeze
> out the manufacturing secret.
> 
> The secret was etching.
> 
> To keep it secret, Bliley had called it something along the lines
> of "X-Grind" and not applied for a patent.
> 
> The Government forced Bliley to share the etching secret without
> giving any compensation, and the Blileys were bitter about that for
> the rest of their lifes.
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.

------------------------------

Message: 2
Date: Mon, 21 Apr 2014 11:26:16 -0400
From: Bob Camp <lists at rtty.us>
To: jfor at quikus.com, Discussion of precise time and frequency
	measurement	<time-nuts at febo.com>
Subject: Re: [time-nuts] optically excite a quartz crystal?
Message-ID: <6B374045-7B1F-4706-8B38-609B4366BAE5 at rtty.us>
Content-Type: text/plain; charset=windows-1252

Hi

Well I can name at least one post war ham (me at age 14) who did not understand 
the need for etch after grinding?

Bob

On Apr 21, 2014, at 11:21 AM, J. Forster <jfor at quikus.com> wrote:

> The etching referred to was by post-war hams,
> 
> -John
> 
> ===============
> 
> 
> 
>> Hi
>> 
>> Early in the WWII era, quartz blanks were not commonly etched after begin
>> ground / polished to frequency. This left debris on the surface of the
>> blank. The net result was that the resonators failed after a period of
>> time in the field, especially under damp conditions. The problem got so
>> bad that it actually threatened the ability to communicate in 1942. A
>> fairly high level team looked into the issue and etching of blanks (and a
>> few other mods) were made a mandatory part of all crystals suppled to the
>> government. Ammonium bi-flouride and water was the most common etchant in
>> that era. There are a number of papers about the whole deal in the FCS,
>> and many stories told by those who were part of the changes.
>> 
>> Bob
>> 
>> 
>> On Apr 21, 2014, at 10:10 AM, J. Forster <jfor at quikus.com> wrote:
>> 
>>> No. There is just a little rectangular quartz wafer. No plating.
>>> 
>>> In fact, post WWII, when many ham transmitters were 'rock bound' (ie:
>>> crystal conteolled) it was common pratice to regrind mil surplus rystals
>>> to move them into the ham banda.
>>> 
>>> Apparently, some were also etched using a cleanser called Whink, which
>>> contains a flourine compound.
>>> 
>>> Also, some advocated applying graphite from a pencil lead was used to
>>> decrease the frequency.
>>> 
>>> If the crystal ativity was low, they were taken appart and cleaned.
>>> 
>>> 
>>> 
>>> -John
>>> 
>>> ==============
>>> 
>>> 
>>> 
>>> 
>>>> I'm puzzling over this statement.  The FT-243's I have seen have a
>>>> spring
>>>> that squishes the quartz blank between the electrodes.  They aren't
>>>> plated
>>>> onto the quartz, but they are still in intimate mechanical and
>>>> electrical
>>>> contact.
>>>> 
>>>> -Chuck Harris
>>>> 
>>>> Bob Camp wrote:
>>>>> Hi
>>>>> 
>>>>> The WWII era FT-243 is one example of a crystal that has the active
>>>>> portion of the
>>>>> electrodes separated from the resonator by an air gap. There are lots
>>>>> of
>>>>> similar
>>>>> holders from that era that do pretty much the same thing.
>>>>> Non-contacting
>>>>> electrodes are not very new.
>>>>> 
>>>>> Bob
>>>> _______________________________________________
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>>>> 
>>> 
>>> 
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> 
> 
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