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Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1365
Registered: 6-2004
| | Posted on Sunday, October 01, 2006 - 1:37 pm: | 
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I've read again and again that this radio or that radio doesn't drift on SSB. That is simply not true. All SSB CB radios drift from cold to warm. Even very expensive HF rigs that don't have a Temperature Compensating Crystal Oscillator (TCXO) installed will drift from cold to warm enough to make a noticeable change in tone on SSB.
Some radios drift more than others, and some drift less than others. Some are basically not suitable to use on SSB because they drift even after they warm up. Some radios drift because the clarifier has been expanded to more than 10kHz. Some have modifications like switched crystals that make an otherwise fairly stable radio drift even after warm up.
The latest reason that folks think their radios don't drift from cold to warm is the use of CB frequency counters that read on TX and RX. Remember that these are not test instruments, they're radio accessories meant to be used as a frequency display. They are by no means accurate enough to detect the small amount of drift that will effect SSB tone. Even if the counters themselves didn't drift at all, the best resolution these counters have is 100Hz (4 places to the right of the decimal) which is enough to make a huge pitch change on SSB without showing any change on the counter's display. But these counters do not have TCXOs or a crystal oven in them, so they drift too. Assuming the counter's oscillator is as good as the radio's oscillator, which it probably isn't, the error could be double the amount of drift by the radio from cold to warm - probably more! All without showing any change on the counter's display.
Another thought about frequency counters used as displays... If putting a frequency counter in a radio was a good way to show the frequency of operation, why don't expensive HF rigs have one? I don't think there have been any since the move from crystal synthesis to PLL, and then it was usually an optional piece of equipment that was expensive and uncommon. I'll tell you why - the use of one oscillator to show the operation of another is less effective and more costly than making the first oscillator frequency stable and using a synchronized display. Also, if the user later wants to add a TCXO as an option, they would have to buy one for the display as well as one for the radio's oscillator. The TCXO for my TS450 was $129.
So to sum it all up, ALL SSB CB RADIOS DRIFT! Please don't claim otherwise. You're driving me $#&()%!@# nuts! |
Bruce
Senior Member
Username: Bruce
Post Number: 4077
Registered: 9-2003
| | Posted on Sunday, October 01, 2006 - 2:56 pm: |
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But some DON'T drift enough to make much of a diffrence. My grant from a cold start has little drift but does have some.
Now I know a radio on 6 meters that it's name says it all ......
The SWAN 2 DRIFTY ....... aka swan 250. |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1367
Registered: 6-2004
| | Posted on Sunday, October 01, 2006 - 3:19 pm: |
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Yes, but it does drift, and the tone does change in direct proportion to the amount of drift. If you talk to someone regularly you can even tell when they just turned on their radio, and/or what radio/microphone combination they're using. When you notice that much detail - which I do and I'm sure many other folks here do as well - you will notice even 10Hz in drift. And that would be on rather expensive amateur HF gear. The smallest drift I've ever seen on any CB was about 30Hz, and that was a Uniden 7.8MHz SSB rig. 30Hz is enough to easily detect even for a novice SSBer. Typical drift is often 10 times that much. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 3239
Registered: 7-2004
| | Posted on Sunday, October 01, 2006 - 5:08 pm: |
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300 hz from cold to warmup, or 300 hz after warmup? from cold to warmup is a given, & hardly worth getting upset over. if after warmup, is that inside a 300hz span, or does it just continue to drift....forever? my XL with the nasty 20kc slide mod will drift continually based on temperature change inside the vehicle-extreme temperature swings will SHOW 100hz on the counter, up & down, but if the temp stays stable, the counter will stay stable-though yes, you can tell a slight change in pitch, though not enough to move the knob. my LT with 5kc standard slide mod in a basement room almost never flickers the counters last digit after warmup.
when listening on LSB ch 38 sometimes, i nearly need to turn it off so as to not go crazy. 10 guys, 10 different radios from CB's to exports to HF rigs & every single one of 'em is on a differnet freq. & they tune & retune to each other,so much i couldn't tell if my radio was drifting if i needed to  |
Hotwire
Senior Member
Username: Hotwire
Post Number: 1840
Registered: 1-2005
| | Posted on Sunday, October 01, 2006 - 5:25 pm: |
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I agree with you 100 percent Hollowpoint! So many times on air I hear guys fussing about drift and being off freq. Its like they have no idea what the clarifier is for. To all those crybabys out there, stop whining and just have fun! |
Unit199
Intermediate Member
Username: Unit199
Post Number: 358
Registered: 8-2003
| | Posted on Sunday, October 01, 2006 - 7:55 pm: |
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WE DO NOT LIVE IN A PERFECT WORLD AND MANUFACTURERS DO NOT MAKE PERFECT RADIOS. ALL RADIOS DRIFT TO SOME DEGREE, SO WHY WORRY SO MUCH ABOUT IT??? I FEEL IF I CAN UNDERSTAND THE PEOPLE I AM TALKING TO AND THEY CAN UNDERSTAND WHAT I AM SAYING, I SURE AS THE HECK COULD CARE LESS. I SURE AM NOT GOING TO SPEND MORE MONEY ON THE RADIO AND HAVE IT STILL DRIFT TO SOME DEGREE.
I LOOK AT IT THIS WAY, THEY DO NOT HAVE TO TALK TO ME IF I AM NOT RIGHT TO THEM ON FREQUENCY, ESPECALLY WHEN THEY ARE NOT EXACTLY ON FREQUENCY EITHER. THE IDEA IS TO TALK AND ENJOY AND NOT WORRY WHETHER YOU ARE RIGHT ON FRQUECY OR NOT.
HARVE
UNIT199 |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1370
Registered: 6-2004
| | Posted on Monday, October 02, 2006 - 11:21 am: |
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All three of my HF rigs drifted from cold to warm. Once warm, they're all quite stable and work well.
Same with my SSB CBs. The CBs drift a lot more than the HF rigs do, but once warm they're quite stable too.
My point here is to clarify the drift issue. People make posts here on the forum saying things like their radios don't drift or they're rock solid even when cold, and that's simply not true unless they've been extensively modified to include a TCXO or crystal oven.
I want folks new to radio or newly interested in the subject to know that it's normal for your radio to drift - especially from cold to warm. It isn't noticeable on AM, but it definitely is on SSB. |
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