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  #1 (permalink)  
Old 02-08-2010, 6:15 PM
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Default Crystals quit working, Why?

I have an old R806 Regency crystal controlled scanner. I ordered crystals for new added frequencies for my area. They worked perfect for a while then they quit receiving. All other crystals still working. Any hints why they quit? I've swapped positions with other crystals and they still won't work.
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Old 02-08-2010, 7:13 PM
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Obvious question, since you didn't specify anything - where are you, and what were you listening to with the crystals? Did those services move to another freq or perhaps a trunk system?

There's nowhere near enough information here to make a diagnosis. 73 Mike
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Old 02-08-2010, 7:27 PM
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Default Crystals quit working

Sorry about not giving enough info.
I was listening to our local sheriff's office and city police. Calhoun County, Hampton, Arkansas Police Dept. both on frequency 155.950. I am still receivng traffic on the same frequencies on three other scanners. I know the local frequencies and they have not trunked. I just retired from the Calhoun County Sheriff's Office.
I tried the crystals in another crystal controlled ( Regency ACT - R10) scanner and they work in that one.
They worked great on the Regency R806 for several months then quit..
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Old 02-08-2010, 8:16 PM
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Quote:
Originally Posted by cbsonnydavis View Post
I know the local frequencies and they have not trunked.
I tried the crystals in another crystal controlled ( Regency ACT - R10) scanner and they work in that one.
They worked great on the Regency R806 for several months then quit..
If you are saying that they DO now work in ACT-R10, but not in R806, then it's possible one set is less sensitive to drift in freq. These things are hermetically sealed. However, the glass can crack around the leads, which would allow air inside. I forget exactly what that does, but I don't think moisture is good for the them.
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Old 02-08-2010, 8:37 PM
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Default Crystals not working

They are the same crystals. I took them out of the R806 and placed them in the ACT-R10 and they work. I tried them again in the R806 and they still didn't work. Put them back in the ACT-R10 and they work perfectly. All other crystals in the R806 in the 150.000 - 160.00 frequency range work. The crystals have not been exposed to moisture. The scanner has been used intirely in a home setting with central heat and air.
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Old 02-08-2010, 8:50 PM
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It could be that the crystals have become a little less active. It could also be that the R806 doesn't excite the crystals quite as much as the R10 does so slightly less active crystals won't vibrate in the R806. I don't think any crystal controlled scanners have been manufactured since the 1970's. So your radio is probably 40 or 50 years old. Time to retire it and let it rest.
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Old 02-08-2010, 8:55 PM
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Thanks! Make sense. Guess I'm a hoader and hate to give them up.
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Old 02-09-2010, 9:32 AM
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Originally Posted by cbsonnydavis View Post
The crystals have not been exposed to moisture. The scanner has been used intirely in a home setting with central heat and air.
Not to belabor the point, but have you heard of relative humidity There is ALWAYS moisture in the air, and very small hairline cracks in the glass would allow that moisture in. Again, not sure if that is your problem.
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Old 02-09-2010, 3:58 PM
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Thanks captclint. And thanks to everyone else. I guess the relative humidity could be the problem. I guess I'll do what "jackj" said and retire the scanner.
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Old 02-09-2010, 4:22 PM
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Um, maybe it's not the crystals that have changed?

Other components can fail, age, drift or otherwise give trouble.
It takes a circuit to oscillate. The crystal is just one part of the circuit.
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Old 02-10-2010, 10:01 AM
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Default cbsonny - crystals quit working

Other crystals still work and have been in scanner for years
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Old 02-10-2010, 11:24 AM
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Quote:
Originally Posted by cbsonnydavis View Post
Other crystals still work and have been in scanner for years
But the "bad" crystals work in the other radio, right?

There is variation in how crystals are cut, how they are mounted and the circuit used to excite them.
So just because another crystal "works" doesn't prove the given crystal is "bad." It just proves something isn't working.

But we're talking component-level circuit repair or adjustment. If all you can do is change crystals then that's all you can do.

But I agree that it's time for a new (to you) scanner. You got your money's worth.
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Old 02-10-2010, 4:09 PM
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Default Crystals not working

Thanks NWOU for the info. I have a hand held police radio, a mobile police radio in my truck (a carry over from my job with the sheriff's office after I retired) a crystal controlled scanner and two programmable scanners. It's not like I need that scanner. Just wondering why it would'nt work. I like to try to make things work. Thanks again.
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Old 02-10-2010, 5:13 PM
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Since the old crystals work and the new ones don't obviously points to the new crystals and nothing else. There may be nothing "wrong" with them per se, just that they weren't cut to OEM specs for that particular scanner. That type of crystal hasn't been in production for years, the manufacturer had to dig out what was left of the old design records and cut a special order. That simply means generic (more or less) or in other words good enough for government work or "gee, I hope this thing works". They tested just fine and were shipped but that's not to say the test circuit exactly matched the oscillator in the scanner, they work but not in that particular circuit being it doesn't quite have the "oomph" to excite them.

The bottom line is this is fairly common when something is long out of production and engineering no longer has exact specs to go by. Crystals have come a long way only they've taken a completely different direction and old data has been archived and annotated to save storage space.

Now have you stopped wondering? (;->)
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Old 02-10-2010, 8:19 PM
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Default crystals not working

Thanks "kb2vxa" for the info. I'll quit wondering.
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Old 02-10-2010, 8:21 PM
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I understand about trying to keep stuff going. The Heathkit HW-101 ham radio I built in 1972 still runs and it makes me happy that it does.

Crystals aren't totally interchangeable and mass-produced like some other components. They are more like musical instruments- cut from a pattern but the materials and workmanship make a difference in how a particular individual part works. (I've seen them being polished and tuned in a crystal manufacturing facility). So one crystal might work fine in the circuit while the next one might not.
Or maybe the new crystals were built assuming a 3rd or 5th harmonic resonance while the radio would rather have one with a fundamental resonance and it seemed to work ok for awhile. (Or something like that.)

The only way to "know" would be to have a really good electronics tech analyze the radio and the crystals and see what's going on. And I expect that very few modern techs could do that job anymore. Some might be shocked at using a piece of rock as a tuning fork in an electronic circuit. When I was working in electronics manufacturing there were several times I had to firmly halt some production line folks from clanking the crystal oscillators (computer clock) like maracas (sp?) in their shipping tubes and reject the parts as damaged scrap.
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Old 02-10-2010, 8:29 PM
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Thanks "NWOU". sounds like you've been there, done that.
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Old 02-10-2010, 9:38 PM
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Quote:
Originally Posted by cbsonnydavis View Post
Thanks "NWOU". sounds like you've been there, done that.

Some.
But even with all that, I still don't know why your crystals aren't working. Sorry.
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Old 02-10-2010, 9:43 PM
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Thanks NWOU for trying to figure it out. The crystals work fine in the older Regency Scanner. I try them in a newer (still an old one) model Regency and they will not work at all.
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Old 02-11-2010, 1:33 AM
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Both scanners are 10.7 I/F so that isn't a problem for you. Do you have the wires set correctly? Is a wire loose? I think the wire should be in position 4 for the slot you are using the crystal in.
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