The AM Forum

Does anyone make crystals to order any more? Yes, I know about Bomar, Crystek... but they link to distributors such as Mouser, and the stocked items are only the standard timing frequencies.

I'm in need of a 2306.7 KHz crystal, preferably in an HC-6/U package. Any thoughts on who would be able to sell me one or two? (It's for a '60's Heathkit, their p/n 404-197 if anyone happens to have one in the junkbox)  8)

Thanks for any tips.

I would suggest starting with a query to AF4K Crystals, by Steve Johnston, WD8DAS:

https://yhst-172765969-1.stores.yahoo.net/

He provides HC-6/U crystals for amateur frequencies, and may also be able to provide one to your specifications.

CTS: https://www.ctscorp.com/connect_product_line/crystals/

Anderson: https://lokoselectronics.com/brands/anderson-electronics-llc/

Klove: https://www.klove.nl/crystals/

Bomar: http://bomarcrystal.com/cgi-bin/orderform_radio.php

Try surplus sales of Nebraska... lots of stuff. Might need to wade through a lot of items.

Here is the website for xtals:

https://www.surplussales.com/index/Crystals.html



Rich

Thanks! I should have mentioned that I already have a query in to AF4K, and I've ordered the nearest one (2304 KHz, only $5) from Surplus Sales because I think I can pull it to 2306.7 ;)

(I tried pulling a 2303.3 that I had, but it would only go to 2306.0 before the oscillator quit, and I don't want to have to start changing parts other than the crystal and an added series trimmer).

I filled out that handy Bomar order form too, I'm sure they'll pull out all the stops for a 1-crystal order  :D

You might want to try finding a crystal a bit above the desired frequency and pull it down with a parallel capacitor. That is what I usually do instead of adding series caps to pull one up. I start with a 3pf or so and add a few pfs until I get it close. I can often get withing 20 Hz or so.

Rich

Will that work in a Colpitts oscillator? I'm not an RF expert  :-\
How far down can you pull, compared to the 1-1.5 ppt up?

According to Netty’s inventory list he has the crystal you are looking for

https://www.nettyelectronics.com/crystals.html

I've pulled the crystals down more than 500Hz for use in Johnson Viking 2, Challenger, Globe Scouts, Heathkit DX60 and even a few CB radio 27mz xtals for use in Lafayette and Olson tube sets. Probably a Colpits in one of them. Usually much more than 10 pf parallel capacitance will affect the oscillator and it will stop.

Looks like Netty might have what you need but sometimes with old xtals you need a little extra capacitance to tweak them to the correct freq.

Rich

Thanks. Before tonight I never heard of the guy! Someone from the Facebook Heathkit group already pointed me to him (Earl, VE3AB) and his inventory shows he has two! I emailed. He replied that he will look for it tomorrow morning  :) Keeping fingers crossed.

I just got this reply from Bomar Crystals: "Sorry we do not have an HC6U holder anymore and we can not do so low frquency using other holder."  ???

Earl says it looks like he sold them :(
But he just got a lot of 500 crystals, mostly Drake and Heath, so once he's sorted them he'll let me know.

Meanwhile, the 2.304 that might pull far enough to use should be here tomorrow.

The 2.304 crystal will pull to 2306.52, almost far enough. It's a bit noisy due to the small series capacitance required to get it that far. But the radio does work for now...

Meanwhile, after posting on quite a few forums, I was directed to a Czech company (http://www.krystaly.cz/en/Products/Crystals) that actually will make crystals in quantity 1 (or more). Their quote for mine was $20 each and $8 postage. Lead time is two months. I think I'll order two.  8)

Interesting to know about the Czech firm.  The cost is what International Crystal would have charged 25 years ago.

When International went out of business, a friend called them and asked what they were going to do with their technical files.  As in the details of specific crystals used in specific pieces of equipment so that you didn't need to tell them the series capacitance, "cut" and all that stuff.  They told him that they had sold or given them to some Canadian firm. Friend then called the Canadian people and was told that either they didn't do small orders or the cost was astronomical.  And that was that.

For many applications the new go-to circuit is the Si5351A synthesizer IC which is slightly smaller than an HC-6/U crystal and can sub for a crystal in some oscillator circuits.  You usually need to add a low pass filter to clean up the square wave to a sine wave but there are kits now hitting the market at less than $ 10.  That won't help you should you need a crystal as a filter component though.