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Cuddlebear
Intermediate Member
Username: Cuddlebear
Post Number: 218
Registered: 3-2002
| | Posted on Wednesday, August 11, 2004 - 10:31 pm: | 
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Hello Guy's,
Recently I've been talking with people about radio alignment and temperature factors, etc. My question is this, What would the proper room temperature be (or) should be while doing a alignment on a radio? This of course after the radio has warmed up. I figure this question would be a very interesting one for the Tech's and everyone else. Thank You in advance folks.
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Bruce
Senior Member
Username: Bruce
Post Number: 1452
Registered: 9-2003
| | Posted on Wednesday, August 11, 2004 - 11:29 pm: |
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here about 75f but i dont see a 68-80f range being a problem |
Tech808
Moderator
Username: Tech808
Post Number: 3278
Registered: 8-2002
| | Posted on Wednesday, August 11, 2004 - 11:47 pm: |
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Personally I never really paid any attention to the temperature.
I would guess I have always set them on the bench with the temperature in the 70-80° range.
Never had any problems with them after that.
This is what I like about the COPPER FORUM, Always New & Unexpected Questions.  |
Cuddlebear
Intermediate Member
Username: Cuddlebear
Post Number: 219
Registered: 3-2002
| | Posted on Thursday, August 12, 2004 - 12:11 am: |
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Thanks for the replies so far. 
You see, the reason for this question is that I have always figured you want to set your radio according to the house conditions you are in. If you keep your house cool, say 65-70 degrees and you set it for that, then if the temp goes up your radio is going to be off frequency at say 75* I have done this with my own equipment and have had this problem. But then if I set them at say 72-73* in the house, then when it cools off, your still off freq. So I have been discussing this with people to try and find the happy medium with a radio. So, I appreciate any and all thoughts on this subject. Another interesting thought would be that this perhaps could very well be the reason why some radios come from the factory slightly off frequency when you buy them. It might have been set right when it was there, but different climate changes etc. Hope this doesn't sound stupid to anyone. Just a theory I have.
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Geekster
Intermediate Member
Username: Geekster
Post Number: 111
Registered: 6-2004
| | Posted on Thursday, August 12, 2004 - 8:31 am: |
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The PLL should help with this on newer radio's. Very interesting question.
The Crystal and components should have a temperature range and the frequency drift at those temps. |
Tech833
Moderator
Username: Tech833
Post Number: 819
Registered: 8-2002
| | Posted on Thursday, August 12, 2004 - 4:24 pm: |
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Temperature means nothing. If the temp is comfortable enough to work in, then it will be fine for the radio.
Here's the REAL issue. When CB 'techs' align a radio, are they checking the output on a spectrum analyzer? Are they aligning for peak out, or are they aligning for resonance and efficiency? You see, a watt meter will show everything coming out of the transmitter. Spurs, harmonics, everything. If you adjust for peak, not all of that power is on your channel!
When aligning the transmitter, the current being drawn should be used along with a selective wattmeter (or spectrum analyzer) to adjust for-
Wattage output ON FREQUENCY (Minimum spurs)
Highest wattage for least amount of current drawn
Minimum harmonics
If you get the most watts ON FREQUENCY with the minimum current being drawn, you will also create less heat. Less heat not only means prolonged radio life, but also a cleaner signal because your output tank will be resonant.
I wish to explain no further. The techs (you REAL techs know who you are) will know what this is about. The 'wanna- bees' will not have a clue or tell me I am wrong. |
Cuddlebear
Intermediate Member
Username: Cuddlebear
Post Number: 223
Registered: 3-2002
| | Posted on Thursday, August 12, 2004 - 5:57 pm: |
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You would think so Geekster,
But I've seen this erratic behavior on newer radios as well. The 696F/SSB base station. The Galaxy 949/DX2547 base etc. even seen it on a Cobra 2010 base. (although the 2010 was a poor sub for the 2000) |
Hollowpoint445
Intermediate Member
Username: Hollowpoint445
Post Number: 237
Registered: 6-2004
| | Posted on Thursday, August 12, 2004 - 10:14 pm: |
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Ambient temperature isn't really an issue if the difference is only 10 degrees. The thing to compensate for when touching up the frequency is the temperature build up in the radio.
I'd suggest you do it this way:
Let the radio warm up for 30 minutes before taking your first frequency reading.
Let the radio on but take the cover off. Let it cool down for 30 minutes and take a second frequency reading.
The first reading will tell you how far off frequency the radio was when warm.
Now make the change using the second frequency reading as the starting point.
Put the case back together, and let it warm up for another 30 minutes.
The frequency should be very close.
I assume you are doing this for SSB operation as AM isn't very frequency sensitive. While I would never suggest modifications that would void type acceptance, there are other ways to compensate for frequency drift on SSB radios.
BTW, PLL's don't compensate for temperature. It is possible to have temperature compensation built into the oscillator circuit, and most do have some compensation built in - mostly by component selection - but it's not the high level that is used in commercial radios or good amateur radios. I would worry more about the voltage regulation than the temperature drift of the oscillator. |
Tech548
Moderator
Username: Tech548
Post Number: 229
Registered: 5-2004
| | Posted on Friday, August 13, 2004 - 1:53 am: |
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Verrrry interesting.
I wrote an article very close to this subject once but decided not to post it for the same reasons that Tech833 gave.
As simple as I tried to make it for all to understand, I was warned that it could cause some controversy and I would more than likely end up defending it and myself from the many questions I would get from the ones who would pick it apart and want me to explain it in further detail.
Lol. Tech833, you handled that one like a Trooper!
Jeff
Tech548 |
Cuddlebear
Intermediate Member
Username: Cuddlebear
Post Number: 225
Registered: 3-2002
| | Posted on Friday, August 13, 2004 - 7:20 am: |
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Very interesting indeed.
By the way folks, This is a learning experience for those of us that are not FULL FLEDGED" TECHS. I am always learning as you folks had to when you started out. I do work with radios in a shop. However, I don't own the shop. And Lets face it, when you work in a Truckstop CB Shop, you are asked to do things by customers you would never want to do in most cases with your own stuff. I however, do not "Normally" work the scope etc, in the shop. I solder the Echo boards, noise toys, Donkey farts, etc. I have worked the generator, etc. when the boss has more than he can handle. But In no way can I ever claim to be a full tech. With this being said though, I do enjoy the technical end of these conversations and learn a lot as well. As we all do. And by the way Tech548, Even though you never posted this article. I would truly love to read it. No Doubt I would learn a ton from it. I seriously don't find it a contriversy at all. The facts are the facts Sir. And Tech833 and Hollowpoint, I found your postings to be very informative as well. Thank you again for all the great input. I would still love to hear more. Hit me with your best shot folks! This is what the forum is for.
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