[Boatanchors] Crystal Grinding
howard holden
holden7471 at msn.com
Tue Jan 5 13:44:12 EST 2021
I like Al’s recommendation for moving a crystal up, and will give that a try. As for if you overshoot a bit, instead of rubbing solder on the crystal, I’ve had very good luck using a Sharpie black permanent marker on one, or both sides of the crystal to lower the frequency. Very important to not use way too much, and to keep the corners where the crystal mounts in between the plates clear of marker. The nice thing is, alcohol will remove most of the marker, and you can redo it if you went too far or if the crystal stops oscillating. Most “amateur” type FT-243s can be moved several Khz, and the original FT-171s can be moved 10-15 Khz or more. Once the marker really dries, the frequency is stable.
73, Howie WB2AWQ
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From: Al Klase<mailto:ark at ar88.net>
Sent: Tuesday, January 5, 2021 9:09 AM
To: boatanchors at mailman.qth.net<mailto:boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] Crystal Grinding
Dave,
Over the years, I've been reasonably successful grinding crystals with
3M Wet-or-Dry from the autostore. 400 grit is a good start.
Place the wet paper on a really flat surface, and move the crystal in a
figure-8 pattern with your finger. Try to only grind one side.
Grinding the edges will often restore activity if the crystal fades out
as you move its frequency. You can only go upwards. If you overshoot
rubbing a bit of solder on the surface can weigh it down and reduce the
frequency a bit. That might not be stable in the long run.
Now, some friends of mine advocate etching with ammonium bifioride. In
fact I have a bit here that they sent me a couple years ago, bu haven't
go around tuit.
There's an article in /Radio & Television/, May 1954
<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fworldradiohistory.com%2FArchive-Radio-News%2F50s%2FRadio-News-1954-05-R.pdf&data=04%7C01%7C%7C32c60817707c4ecc64cf08d8b19cb6b2%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637454633947144913%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Sdp0x5ptVOOm4QJAX7e8jJLgNkYp5D2BKzyia4cAxng%3D&reserved=0>,
page 38 that cover this.
Ammonium bifloride is about $45 a pound on Amazon
<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.amazon.com%2FChemsavers-Ammonium-Bifluoride-96-5-500g%2Fdp%2FB07J5QV4MG%2Fref%3Dsr_1_1%3Fdchild%3D1%26hvadid%3D78134057362565%26hvbmt%3Dbp%26hvdev%3Dc%26hvqmt%3Dp%26keywords%3Dammonium%2Bbifluoride%26qid%3D1609864739%26sr%3D8-1%26tag%3Dmh0b-20&data=04%7C01%7C%7C32c60817707c4ecc64cf08d8b19cb6b2%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637454633947144913%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=7ZaNVfv1J1VeQxZ8AyMqhalldiiHECRvcs2tiOFPWeQ%3D&reserved=0>.
That's all I know,
Al
On 1/5/2021 7:20 AM, David Stinson wrote:
> Some folks have mentioned they grind crystals.
> Never had much success doing so-
> I've killed many a crystal.
>
> If you do have more positive results,
> please detail exactly what you use and
> how you do it. Old dog seeks new tricks.
>
> TNX DE Dave AB5S
>
>
--
Al Klase - N3FRQ
Jersey City, NJ
https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.skywaves.ar88.net%2F&data=04%7C01%7C%7C32c60817707c4ecc64cf08d8b19cb6b2%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637454633947144913%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=OULWhi7a02FBSf7qDpM1ll3%2F5YWtCqrMJnnBm9kmCB4%3D&reserved=0
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