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1st Anniversay - the new AF4K Crystals




 
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Author Topic: 1st Anniversay - the new AF4K Crystals  (Read 926 times)
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wd8das
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« on: April 20, 2022, 12:26:01 PM »


We have passed the one-year anniversary in the operation of the new AF4K Crystals.  Thank you to everyone who has supported my restart of this important resource for our hobby.  I've really enjoyed helping folks with crystals for vintage gear and homebrew projects!

If you've been thinking of ordering something, now might be a good time.  I have been contemplating some price "adjustments".  HI HI

http://af4k-crystals.com/


73   Steve WD8DAS

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WD4DMZ
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« Reply #1 on: April 20, 2022, 11:08:12 PM »

Hello Steve. Last August I purchased a few from you and they worked fine in a DX60, Johnson Challenger and two different Globe Scouts. Pleased and would recommend them for AMers with boatanchors.

Rich
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wd8das
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« Reply #2 on: April 21, 2022, 12:10:59 PM »


Thank you Rich.  I really appreciate your report. 

In response to my recent postings on various forums, Facebook, etc, a couple guys have said they "heard" that you can't trust modern crystals in vintage equipment.  These guys have not had a problem themselves, they are just passing along the story.

Of course, some oscillators do work crystals very hard and even FT-243s can fail.  One-tube power oscillator CW transmitters are a good example.  But multi-stage rigs rarely apply too much voltage or current to the crystals, and the modern units perform nicely as in your experience. 


Steve WD8DAS

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wd8das
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« Reply #3 on: April 21, 2022, 12:11:52 PM »


If anyone would like an independent review, see the article in Electric Radio magazine May 2005 by G3UUR. Materials science expert Dr. David Gordon-Smith, G3UUR conducted some very tough tests on these crystals using a high-powered Pierce power oscillator circuit and discovered that they were quite rugged.

In some cases they can actually prove to be MORE reliable than the old World War Two era FT243 crystals.  He felt their crystalline structure is more pure and less prone to failure.


Steve WD8DAS

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WD4DMZ
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« Reply #4 on: April 21, 2022, 12:58:05 PM »

About 6 years ago I purchased 10 or so when Bry was still around and filled my Viking 2 with them. Still all there and doing fine. Had to add a parallel 5 uuf cap to pull them down a bit as they ran high a few hundred Hz in the V2 but stable ever since. Got them all within 50Hz.

One 7295khz did fail in an old Globe Scout I picked up on eBay. Not sure what caused it but at some point a 6W6 was subbed for the 6V6 oscillator. The 6W6 is a heavier duty tube so I put a 6V6 back in its place. Was just using the GS this week and the xtal is OK but to be safe added a 100 ohm resistor in series with it.

With original FT243 xtals so hard to find for the AM frequencies these are a good option.

Rich
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KD6VXI
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Making AM GREAT Again!


« Reply #5 on: April 21, 2022, 06:12:55 PM »

Congrats on keeping Bry's name and keeping the business going.

Are you doing custom grinds yet?   I've had inquiries from people for oddball frequencies and didn't know if you where doing them.  One guy wanted to build an xtal filter so he needed a few.

Again, great job, especially with covid going on.  Glad you are a supply chain that didn't dry up!
--Shane
WP2ASS / ex KD6VXI
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wd8das
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« Reply #6 on: April 23, 2022, 08:22:56 AM »


Thank you, Shane.  I doubt it would be practical to manufacture crystals myself for sale to others.  Grinding old FT-243s is similarly unlikely:  It would be a fun hobby project, but the time involved would make it prohibitively expensive as a business venture.

Steve  WD8DAS


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