Question for old crystal scanner guys

fredg

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#1
I have been into scanners since the late 1970's started off with crystal scanners and still love them!

I of course have a new digital scanner (BCD-325D) but since I live in an area that still has some PD, Fire and other stuff on VHF and UHF I still get to play with my crystal scanners!

I have two Realistic scanners (Pro-53 and Pro-55) that for some reason are fussy about the 460.200 frequency. The 3 crystals I have now work fine in a Regency scanner I have but are off frequency in the Realistic scanners. The Pro-55 is brand new in the box.

I guess it is possible that the 3 crystals I have now are just bad enough to not work in the Pro-53 and Pro-55 but close enough for the Regency ACT-E-106 scanner. Maybe the Realistic scanners are more sensitive to the exact frequency.

I have other UHF crystals that work fine in the Pro-53 and Pro-55, 453.400, 453.775, 460.100 all work fine, 460.200 gives me nothing!

I called Gary at Scanner Crystals | Bearcat Regency Police Fire EMS Radio Scanner Crystal who really knows his stuff. He said that some scanners need the crystal tuned just for that model and that is why he always asks what make and model the scanner is when ordering crystals, it is not as simple as 10.7 or 10.8 in some cases.

Anyway, he said he is going to see if he can get me a 460.200 crystal tuned for my Pro-55, so I am hopeful!

I posted this to see if any old timers remember this sort of thing...

Anyone??
 

fredg

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#3
I don't know who manufactured the 53 or 55, but if it was uniden (bearcat), a regency crystal will not work
They are RadioShack 10.7 IF scanners as I mentioned above. I also have Bearcat crystal scanners so I am aware of the difference (10.7 IF vs 10.8 IF).

Thanks!
 

ko6jw_2

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#4
Commercial crystal receivers had netting trimmers to precisely adjust the oscillator using the discriminator test point. Only a tiny number of consumer scanners offered this feature. The problem is that the tolerances for receiving crystals were not very tight. I remember returning crystals to me local radio distributor many times until I got one that worked. The IF is not the only parameter to be concerned with. Most scanner crystals were 3rd overtone mode plus or minus the IF frequency. It is important to have the correct design if the crystal is to work properly.
 

fredg

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#5
Commercial crystal receivers had netting trimmers to precisely adjust the oscillator using the discriminator test point. Only a tiny number of consumer scanners offered this feature. The problem is that the tolerances for receiving crystals were not very tight. I remember returning crystals to me local radio distributor many times until I got one that worked. The IF is not the only parameter to be concerned with. Most scanner crystals were 3rd overtone mode plus or minus the IF frequency. It is important to have the correct design if the crystal is to work properly.
Thank you! I thought something like that but did have the technical details!

Like I said, Gary at scannercrystal.com understands what you said above, so hopefully he will hook me up!!
 
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#6
I don't remember which RS models are which, but several RS models don't use standard Regency 10.7 crystals for UHF - they use special RS crystals. Those same radios do use standard Regency 10.7 crystals for VHF, but require different ones for UHF. I'm not familiar with your models, but I know that that the PRO-14 and PRO-16 scanners, for example, require the special RS UHF crystals. It's not about crystal tolerance, but rather the formula which relates the actual frequency of the crystal to the desired receive frequency.

I gather from your original post that this probably isn't the problem you're experiencing (since your other UHF crystals work), but it' something to be aware of.
 

fredg

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#7
I don't remember which RS models are which, but several RS models don't use standard Regency 10.7 crystals for UHF - they use special RS crystals. Those same radios do use standard Regency 10.7 crystals for VHF, but require different ones for UHF. I'm not familiar with your models, but I know that that the PRO-14 and PRO-16 scanners, for example, require the special RS UHF crystals. It's not about crystal tolerance, but rather the formula which relates the actual frequency of the crystal to the desired receive frequency.

I gather from your original post that this probably isn't the problem you're experiencing (since your other UHF crystals work), but it' something to be aware of.
Yeah it's weird... my 453.400 and 453.775 crystals work fine but none of the 460.200 crystals work in the Realistic scanners but they work fine in the Regency scanner.

I did note one thing... the UHF crystals that work are marked with a "P-5" so I am hunting down a 460.200 crystal with the "P-5" marking.

Does anyone know what that stands for? The ones marked "RCD-1" and "TMR" do not work in the Realistic scanners.

The whole this is: "P-5 SD" or "P-5 KCC" I am guessing the SD and KCS are manufacturers but what is the P-5?

Here is an example of the P-5 markings, anyone have some like these in 460.200 and 453.775?
 

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cmaness2001

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#9
fredg:

Your post does not indicate if the crystals that do work in your Realistic scanners also work in your Regency scanner.

If they do then I don't know what the problem is.

If they don't then refer to the post above from oracavon, he is spot on, the formula to calculate the UHF fundamental frequency for certain Realistic scanners is different from Regency, Craig, Midland, etc..

I have a handful of these types of crystals in UHF but the closest I have to 460.2 is 460.25, no joy.
 
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