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was 12oclock,now 1o thirty..

Everything 'drifts' to some extent, especially while 'warming up'. That goes for those test equipment devices too. Solid state stuff tends to 'drift' less than the older "hollow state" stuff, but it's still there. Drifting is a normal thing to happen with heat. That's one reason why crystal ovens are used in more expensive devices.
Depending on how/where a radio is used, after some use you tend to have a 'feeling' about 'when' your radio has settled down to it's normal state of accuracy. Before then, you more or less have to 'wing it', not get too agitated if someone tells you you're off frequency.
Adjusting, or calibrating frequency accuracy isn't something that's done very 'accurately' by ear unless your radio is specifically designed to be 'tuned' that way. Even so, you are only going to get 'close'. And the biggy is just how accurate is your frequency standard? And how 'wide' is the mode you are using to do that calibrating?
If you have a frequency display of 18 digits (yeah, right :)) you'll notice that the last several digits are changing almost continuously, and that's about as normal as you get. And then you get to ask yourself, just how accurate is the person complaining about how far off frequency YOU are.
The bottom line is that if you don't have the equipment to do that checking, don't try calibrating the thing. The chances of you getting it 'right' are very slim...
- 'Doc
 
Doc,,seems like everybody i tune into now is 10,30 or 11.00..and was worried my tx mite be off since my rx changed..but since my clarifier is unlocked maybe it makes no difference since the tx is sapposed to track ''with'' the rx and so no matter where i recive someone my tx should be right there whether the clarifier is dead noon or not.........
 
You should ask the folks on the other end of the line where their clarifier is set to tune you in. The more reports you get, the higher your confidence of where your TX is, high, low, or good enough...

Do you know even 3 locals who would be willing to play? Set your clarifier to high noon and have them tune you in and report the position. In theory, if they have unlocked clarifiers too, then they should automatically come into tune on your receive as they tune you in.

Maybe you could just pull off the clarifier knob and put it back on, set to an hour or so back...what's the range of the clarifer on that unit anyway?
 
The problem is that there are few radios ever 'tuned' the same. Several reasons for that. So, you may have the 'problem, or they may have the problem. When the 'standard' used for that tracking, Xmtr with Rcvr thingy, isn't the same in every instance, there will be differences.
- 'Doc
 
FCC requirement for frequency accuracy is ±0.005% (97.625). So in a worst-case situation, and assuming Channel 20 just for the illustration, you could be on 27.2036... and another station on 27.2064... (which is a difference of almost 3 KHz), and you'd still both be within specification.

Unless you or the guy who maintains your radio has frequency measuring equipment that is accurate to within 0.0005% (note the extra zero) and unless this equipment is calibrated using a system traceable to NIST and within the calibration period specified by the manufacturer, the accuracy of your radio can't be guaranteed.
 
Beetle said:
Well and good, but the FCC only requires ±0.005%, the actual frequency limits depending on the specified channel frequency. In my example, using Channel 20, it's 27.205 MHz.
Click to expand...

so you're OK with the government telling you how good your equipment should perform? Even the mfg spec is abysmal IMHO...leave it to uncle sam not to be out done...
 
C2 said:
so you're OK with the government telling you how good your equipment should perform? Even the mfg spec is abysmal IMHO...leave it to uncle sam not to be out done...
Click to expand...
The FCC requirement is how the equipment MUST perform. If the manufacturer is able to adhere to a tighter standard, that's fine too. I seriously doubt that most CB radios that get mounted in a 4-wheeler and get bumped, bounced, doused with water and exposed to direct sunlight for hours on end and otherwise abused really stay within that ±300Hz for very long.

And by the way, my earlier example indicated that per the FCC's requirements, a CB transmitter on Channel 20 could have as much as 2.8 KHz (almost 3 Kilohertz) of error. Does a typical stock CB have only a maximum error of 300 Hertz?
 
Beetle said:
The FCC requirement is how the equipment MUST perform. If the manufacturer is able to adhere to a tighter standard, that's fine too. I seriously doubt that most CB radios that get mounted in a 4-wheeler and get bumped, bounced, doused with water and exposed to direct sunlight for hours on end and otherwise abused really stay within that ±300Hz for very long.

And by the way, my earlier example indicated that per the FCC's requirements, a CB transmitter on Channel 20 could have as much as 2.8 KHz (almost 3 Kilohertz) of error. Does a typical stock CB have only a maximum error of 300 Hertz?
Click to expand...

Hope you don’t mind my bantering…

OK, you're right and not right. They cannot have 2.8 kHz of error.
(note, it's lower-case 'k' according to NIST Special Publication 811 - 2008 Edition
‘K’ is to be used for kelvin – spelled out with a lower-case ‘k’)

The following is in context of a typical Galaxy CB radio, but the 2970N2 has the same basic specs.

The CB mfg's typically use a Frequency Tolerance specification of 0.005%, or 1360 Hz @ 27.205 MHz. That means the error can be at most 1360 Hz from 27.205, not 2800 Hz. In your example, 2800 Hz would be the difference between the maximum and minimum allowable frequency (2720 Hz), not the actual error – but you already said that earlier.

Yes, I do believe this spec is typical performance when the radio leaves the factory and is operated normally, but I have seen them as far off as 1700 Hz (±10 +1 @ 95%) out of the box, in my limited experience, and that would be out of spec.

They also use a Frequency Stability specification of 0.001%, which is where I was getting my approximate 300 Hz spec. That would be the "drift" spec once the radio is stabilized and operated over it's operational environmental specification. I don't know what that environmental spec is, but they do list -30 C to +50 C.

My tests indicated a regular frequency drift of 50 Hz over a 20 F temperature range in a 24 hour period. I no longer have my notes, but the drift curve could have been extrapolated over a broader range with a great amount of error. If we take the drift as having a linear characteristic, then the total expected drift over the 144 F temperature range is about 360 Hz – fairly close to their spec. I would not be surprised if they meet that spec, but I would not be surprised if they didn’t either. I would be disappointed.

I don’t have a lot of datapoints to support my claims, but I measured two DUT’s over a 1 year period and found both units to meet all published specifications when operated under typical operating conditions (in a passenger vehicle driven over public highways – and my state is ranked #1 for potholes).

A potential problem with these radios when used in SSB mode is that the receive clarifier may not be capable of overcoming the specified frequency error. Many Galaxy CB radios spec a clarifier range ±1 kHz. The 2970N2 specifies ±0.5 kHz.

If I take that last figure and apply it to the OP situation, and assume that the clarifier tuning range is from 7 to 5 o’clock, and he sits at 10:30 to tune folks in (we’ll assume they are dead on, and that the clarifier is linear), then his receive frequency is off by 15% of 1000 Hz, or 150 Hz, and that is not at all bad…

Each 'hour' of the clarifier is 100 Hz.
 
C2 said:
Hope you don’t mind my bantering…

OK, you're right and not right. They cannot have 2.8 kHz of error.
(note, it's lower-case 'k' according to NIST Special Publication 811 - 2008 Edition
‘K’ is to be used for kelvin – spelled out with a lower-case ‘k’)

The following is in context of a typical Galaxy CB radio, but the 2970N2 has the same basic specs.

The CB mfg's typically use a Frequency Tolerance specification of 0.005%, or 1360 Hz @ 27.205 MHz. That means the error can be at most 1360 Hz from 27.205, not 2800 Hz. In your example, 2800 Hz would be the difference between the maximum and minimum allowable frequency (2720 Hz), not the actual error – but you already said that earlier.

Yes, I do believe this spec is typical performance when the radio leaves the factory and is operated normally, but I have seen them as far off as 1700 Hz (±10 +1 @ 95%) out of the box, in my limited experience, and that would be out of spec.

They also use a Frequency Stability specification of 0.001%, which is where I was getting my approximate 300 Hz spec. That would be the "drift" spec once the radio is stabilized and operated over it's operational environmental specification. I don't know what that environmental spec is, but they do list -30 C to +50 C.

My tests indicated a regular frequency drift of 50 Hz over a 20 F temperature range in a 24 hour period. I no longer have my notes, but the drift curve could have been extrapolated over a broader range with a great amount of error. If we take the drift as having a linear characteristic, then the total expected drift over the 144 F temperature range is about 360 Hz – fairly close to their spec. I would not be surprised if they meet that spec, but I would not be surprised if they didn’t either. I would be disappointed.

I don’t have a lot of datapoints to support my claims, but I measured two DUT’s over a 1 year period and found both units to meet all published specifications when operated under typical operating conditions (in a passenger vehicle driven over public highways – and my state is ranked #1 for potholes).

A potential problem with these radios when used in SSB mode is that the receive clarifier may not be capable of overcoming the specified frequency error. Many Galaxy CB radios spec a clarifier range ±1 kHz. The 2970N2 specifies ±0.5 kHz.

If I take that last figure and apply it to the OP situation, and assume that the clarifier tuning range is from 7 to 5 o’clock, and he sits at 10:30 to tune folks in (we’ll assume they are dead on, and that the clarifier is linear), then his receive frequency is off by 15% of 1000 Hz, or 150 Hz, and that is not at all bad…

Each 'hour' of the clarifier is 100 Hz.
Click to expand...

I've been using KHz since it stopped being "kcs" - 50 years or so. I've never been misunderstood on a radio forum (and I'm sure you didn't misunderstand what I intended to say :D ).

No problem with banter at all! My point was/is that given a center frequency of 27.205 and figuring a tolerance of 0.005% as specified by the FCC, the actual frequency could be anywhere from 1360 Hz below to 1360 Hz above, for a total span of 2720 Hz, or 2.72 kHz, or "almost 3 kHz". If a particular radio was right on the ragged edge of being within this frequency tolerance band, the extra 300 Hz or so of drift might push it over the limit.

And once again, it comes down to whether the "tech" has the right measuring equipment, calibrated, and the skill to use it properly. Having seen some "calibrations" done by checking one ±5% meter against another ±5% meter, I tend to be skeptical.
 
whelp i gess shes txing right on..i hooked up my magnum in another room with no antenna n the rf gain turned clear down..i locked the tuner plus 3 on and played a recording of my voice ,40 count, on the 2970n2 n ran back to the magnum room n clarified my own voice in..even though the n2 clarifier was at 10,3o or 11.00 when i clarified myself in the magum clarifier was at dead noon which it normaly is when i listen ham guys with good equipment with the magnum ..
 
Good test using another receiver.

A lot of emphasize is put on clarifier position, sometimes to an overwhelming point.

Can you clarify the station in you are trying to make a contact with?
Can you make the contact and have a QSO?

Then who really cares "where" the clarifier is as long as the op can make the contact and is understandable.

If the radio, rig, transceiver is not able to clarify another station in, if the clarifier has been butchered up and can not be stabilized for whatever reason then it is time to visit the technician or turn on the test equipment if you have it.

I have listened to to many stations chasing each other around the spectrum trying to get on the same frequency. Sometimes it is comical, especially when one of the stations is using a class C splatter box and has his mic gain cracked wide open on SSB.

Point is, if you can make the contact, and you can understand the other station, then TALK on the radio and enjoy the hobby. Stop stressing the little things like where the clarifier is or what position etc, etc,

CB or HAM all have some ops a little off frequency, just dial them in and enjoy the hobby.
 
I also wanted to add that one of the Galaxy service manuals I've used specified an adjustment limit of ±20 Hz on the intermediate loops.

Anyway, the radio is well within shelf spec.
 

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