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Ironmike
Junior Member
Username: Ironmike

Post Number: 11
Registered: 6-2007


Posted on Wednesday, October 21, 2009 - 12:48 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

What would cause an old 23-channel 135 to drop in frequency? For example- keying up at 27.185 and dropping .165, .125, . 26.995 etc in a few seconds? Also it seems that some blocks of 4 channels seem to work ok. 17-20 seem to have the most trouble.
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Moderator120
Moderator
Username: Moderator120

Post Number: 482
Registered: 11-2006


Posted on Wednesday, October 21, 2009 - 10:59 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Ironmike, I have no idea, but my Tech loves those radios. I just sent him an email, if he has any ideas I will post them here for you as soon as I get an answer!
Mike
Moderator120
CEF#0120/HAM #222
KB1NYD
CVC#0041
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Wcsd106
New member
Username: Wcsd106

Post Number: 2
Registered: 10-2009
Posted on Friday, October 23, 2009 - 5:39 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Sounds like you have a crystal dropping out. Those 23 channel radios had crystals that controlled about 4 channels each.
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Moderator120
Moderator
Username: Moderator120

Post Number: 484
Registered: 11-2006


Posted on Saturday, October 24, 2009 - 7:03 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Ironmike: sorry for the delay, he did send me a reply. And Wcsd106 is right on the money. But here is what my Tech had to say on this topic:


His problem is a bad crystal, or a the oscillator for that crystal. Most likely bad crystal though. The clue was that the banks of 4 channels. In most 23 channel controlled radios they linked 1 crystal which controlled 4 channels. So the match is to figure haw many sets of 4 fit into 23 :-) . One other possibility is that it could be a dirty contact on the channel selector knob, but I doubt that is the issue he is having. That's pretty much at the bottom of the list, where the crystal being the culprit is at the top of the list.

It may be thermally intermittent. This means that it is ok at first because it is running with no load, then it is switched on when the PTT is pressed. As it starts getting voltage and current through it, it begins to heat up quarts. This causes the quarts to expand, therefore changing it's internal capacitance / frequency, and hence the change in transmitted frequency. Find crystal linked to that group of 4 channels, and replace.
Mike
Moderator120
CEF#0120/HAM #222
KB1NYD
CVC#0041
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Ironmike
Junior Member
Username: Ironmike

Post Number: 12
Registered: 6-2007


Posted on Sunday, October 25, 2009 - 10:30 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I sure do appreciate it. I wonder if it is worth ordering a crystal to see. Maybe your tech would be interested in some business?
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Moderator120
Moderator
Username: Moderator120

Post Number: 486
Registered: 11-2006


Posted on Monday, October 26, 2009 - 6:51 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I would think it would not be worth the money to be honest, but if you love the radio and have the money then you go for it. The shipping of the radio would really drive the price up as well.
Mike
Moderator120
CEF#0120/HAM #222
KB1NYD
CVC#0041
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Tech291
Moderator
Username: Tech291

Post Number: 538
Registered: 11-2004


Posted on Monday, October 26, 2009 - 8:51 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

a better source is to find a junker that uses the same crystal layout.shouldnt be to hard to find as there were only about 3 common layouts in popular use by most of the manufacturers.


tech291
cef291/cvc6
kc8zpj
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Ironmike
Junior Member
Username: Ironmike

Post Number: 13
Registered: 6-2007


Posted on Monday, October 26, 2009 - 10:53 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Well, that's true- but SSB radios had a different scheme.

I have a cam 89 and a courier conqueror II but they are AM.
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Bruce
Senior Member
Username: Bruce

Post Number: 5215
Registered: 9-2003
Posted on Tuesday, October 27, 2009 - 6:20 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Jan crystals ft myers fl
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Ironmike
Junior Member
Username: Ironmike

Post Number: 15
Registered: 6-2007


Posted on Wednesday, October 28, 2009 - 11:51 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Now that brings back memories... Them and Bomar...

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