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Galaxy radio drift

Martian said:
If you listened to shakes on air it was all about the money and fame.
Not a real product. He was going to "get rich" by getting parts and potting them in epoxy.

This is something real.
What's going on here is that the oscillators have been replaced with a programmable clock generator that's referenced against a temperature compensated crystal oscillator.
So, yes, it's possible and likely that the "drift" of that radio has been substantially reduced by doing the above.

But as shown earlier, the drift in a 2547 was substantially reduced by changing a cap, too.
Click to expand...


And still a work in progress, it can only get better! I am into any thing that saves me the bother of doing it myself even if the route they took is probably not the way I would have done but their result looks like it will be in the end better than my approach ( I am more of an analog designer and only use fixed logic and avoid micros if I can)

If a mod kit can be marketed at reasonable cost it will certainly go into my 95T2
 
Doing that in logic would be rather large, unless implemented in a HDL.
That would be like using C4 to kill ants, not to mention the time to design it.
A microcontroller is the way to go for something like this.

That RF performance has to be improved or your receiver is going to sound like gravel in a washing machine.
 
Just got back from month long vacation road trip, 4 states with a 4wd and trailer through both desert and tropical areas of the country. The radio was measured again when we got back and it had drifted 4 hertz lower, so average one hertz a week.

On air most people said i was spot on freq, but maybe our ears are getting soft at our ages and me or the others on the channel cant pick a 4 hertz error. In our line of work (mine site electrician) a 4 hertz error or even a 1 hertz error would send circuit breakers and fuses popping but im guessing its not so critical with radio communications.

How critical is a frequency shift of that size? The radio was used mostly on lsb and occasionally on usb, but never on am or fm as those modes aren't used here in oz.
 
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4Hz is going to be hard to hear.
40 you will probably hear if it changed while you were talking to the person while it changed.

But if it's adjusted and drifts 1Hz a week that's quite poor for a TCXO.
 
They said the drift was from the 10.240 crystal which is outside of the TCXO control. They offered to fix it but we declined as neither me or the others on the channel could pick it by ear. Moved on to my next radio now, 42 year old Kraco.
 
Let's be fair about this, too.
It's a CB radio. a few Hz drift isn't going to make or break it.
We are not trying to lock a signal that's out past Jupiter.

Within a few Hz? Mission accomplished.
 
Whilst 4 Hz is measurable its barley relevant, and as has been said its from A Xtal outside of the lock and may well just be standard Xtal aging.
 
Tech said it was more likely to be temperature variation but in the end it was not worth losing sleep over because my old ears cant pick a 4 hertz error so we left it at that. Good enough for me.

Next radio currently being done is a kraco ssb de luxe base radio from 1976. Apparently it doesn't have a 10.240 crystal circuit so that radio should be stable to within 1 hertz after its 80 channel conversion. But won't be back to sydney for a couple of weeks so told them to take their time with it.

But back to the export radio. My question was would a four hertz error be noticeable on lsb and usb? Most folks say not.


Loz!
 
Being a CB operator from back in the heyday of the 1970's myself it great to see some of the old gear still being used, I doubt that there have been many improvements in later radios except for the inclusion of micro processors to do some of the heavy lifting.

I still have a few of the older AM only radio's here in NZ but unfortunately many of my older USA built radio's have been sold on or just simply vanished with the passage of time.

Cant see that 4 Hz would be readily discernible as a difference
 
A MAJOR problem with these is the NP0s they used were likely not NP0s - or VERY bad ones and from what I can tell they are 20% parts.

When you have that much variation you have drift. Replace their NP0s with REAL NP0s and something a tad better than 20% and you will be fine. We tested this in a couple of radios and they were much more stable afterwards.

If I was a betting person they specified NP0s of a few percent and they got manufactured with the 20+% variants OR ordinary ceramics because they are far cheaper. That happens all. the. time. and it is up to the company getting the product made to verify that the ODM or your manufacturing facility is not swapping parts.

And no, you cannot send then your reels or flats and rely on them to use the parts you supplied.
 
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ghce said:
Cant see that 4 Hz would be readily discernible as a difference
Click to expand...

Couldnt pick it by my ears. Anyway it got better with age, it drifted back 1 hertz the other way so now its only off by 3 hertz, close enough for me.

Got the krako ssb de luxe base back today from its 40 channel plus conversion, its drifted from cold to hot by 1.5 hertz, a bit better than the superstar ranger thing, but sounds spot on to me on lsb. Did a video of it and asked the young fellow here to put it on youtube and gave tech the ok to post pics of my radio, both the vid and the technical details should be online by tomorrow.

The conversion used the same mod and parts as the superstar ranger radio but programmed and wired differently, tech said the drift was lower because the kraco does not have the 10.240 circuit that caused the 4 hertz drift in that radio.

Loz!
 
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