Finally stopped the Galaxy / ranger drifting

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cb4ever104
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Re: Finally stopped the Galaxy / ranger drifting

Post by cb4ever104 » 18 Jun 2019, 10:24

bigal68 wrote:
18 Jun 2019, 08:47
Hi Sue,

Any news on the trials??
Hey , hey ... Join the queue mate . Sue's working on my ADAMS expansion board first , and then she's got the LINCOLN chipswitch to do :)

Only kidding of course :D She's a busy bee at the moment .
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: Finally stopped the Galaxy / ranger drifting

Post by bigal68 » 18 Jun 2019, 18:49

Yeah, not 'arf!!

Hello mate, hope you're well. I would have thought a man of your capabilities would have done his own ADAMS board...... :thumbup: :thumbup: :thumbup:
Alan 26FB806
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Use it or lose it!!!!

lbcomms
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Re: Finally stopped the Galaxy / ranger drifting

Post by lbcomms » 18 Jun 2019, 20:29

Just finishing off the 858 (Adams) version, waiting for one part on the slow ebay boat from China to arrive.

The 3900 on the last page is still going well, on its second trip around the country now, everything from hot deserts in the middle to alpine weather in the south. Still no drift, owner reports it hasn't moved since it was done. So the idea works, just need to make it into an owner-installable single board design. Long term spare time project.

Haven't seen a suitable 2510 on eBay or Gumtree yet, one will turn up eventually. But want to finish the drift killer off first before starting that one...

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Re: Finally stopped the Galaxy / ranger drifting

Post by cb4ever104 » 19 Jun 2019, 09:16

bigal68 wrote:
18 Jun 2019, 18:49
Yeah, not 'arf!!

Hello mate, hope you're well. I would have thought a man of your capabilities would have done his own ADAMS board...... :thumbup: :thumbup: :thumbup:
I can build them Alan , but Sue's the programmer and designer :)
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.

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Re: Finally stopped the Galaxy / ranger drifting

Post by Edd200sx » 07 Jul 2019, 08:17

Awesome. I’d love one for the 69ffb4 ranger 😍

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Re: Finally stopped the Galaxy / ranger drifting

Post by Edd200sx » 09 Jul 2019, 20:51

lbcomms wrote:
18 Jun 2019, 20:29
Just finishing off the 858 (Adams) version, waiting for one part on the slow ebay boat from China to arrive.

The 3900 on the last page is still going well, on its second trip around the country now, everything from hot deserts in the middle to alpine weather in the south. Still no drift, owner reports it hasn't moved since it was done. So the idea works, just need to make it into an owner-installable single board design. Long term spare time project.

Haven't seen a suitable 2510 on eBay or Gumtree yet, one will turn up eventually. But want to finish the drift killer off first before starting that one...
Make it short term. 😂

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Re: Finally stopped the Galaxy / ranger drifting

Post by bigal68 » 28 Oct 2019, 15:05

Hi Sue,

Just a quick enquiry, as I'm sure you're up to your neck in it.....

How's the drift killer coming on? Has your man let you know how the field trials went?

And after getting told off last time, hows Paul's ADAMS board getting on....? :thumbup: :thumbup: :thumbup:
Alan 26FB806
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Re: Finally stopped the Galaxy / ranger drifting

Post by lbcomms » 29 Oct 2019, 14:00

bigal68 wrote:
28 Oct 2019, 15:05
Just a quick enquiry, as I'm sure you're up to your neck in it.....
That's an understatement. But we are making steady progress on it :thumbup:
How's the drift killer coming on? Has your man let you know how the field trials went?
He's had it for just on a year now, and we did another one early this year in a similar radio. Both of the owners reported no audible drift since they had the prototypes fitted, in all conditions from Victorian snow to summer in the desert. The idea works OK, what we've been working on is a way to make it DIY installable with only basic test gear / tools.

We also want it to be adaptable into most of the common SSB radios. And no physical alignment / calibration, that will all be done with an app.

The first one will be back here in a few weeks for a checkup. I'd be surprised if it has drifted more than 20Hz since it was first modified.

For the experimenters, I'm also doing a cut down "DIY" version (hi Sammy!). This one will use off the shelf "ebay" parts and no SMT soldering needed. It won't be as stable (at high temperatures such as 35 degrees plus) or quite as smooth in the clarifier, but won't need the board that we are currently finishing the design of. It also will be easy to revert the radio back to standard later on - the channel switch wiring does not get touched in the conversion, unlike the earlier EPROM / Binary adder / MCU mods.

Back to the one currently being prototyped. This week it was the carrier oscillator circuit that was cleaned up. Not needed so much for the 858 chassis as that already has a very stable carrier oscillator, it's more for the "exports" and the uPD2824 radios that use 3 inductors to set the carrier offsets. Ended up using an SMT ceramic filter.

The joys of prototyping - it'll look a lot neater in a few weeks when the new design boards arrive.

Image

Image

The dowmix signal doesn't need this filtering, as any low level spurs will be eliminated by the loop filtering in the radios existing PLL circuit.

Next - finalising the board design and ordering / loading the first batch. Hopefully within the next few weeks.

To be continued...

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Re: Finally stopped the Galaxy / ranger drifting

Post by bigal68 » 02 Nov 2019, 13:36

Hi Sue,

Thanks for that.

Going back to a previous post on this thread, replacing the VCO is potentially the next step. But how far do you go??

Eliminating the xtal drift out of a Superstar/Ranger boarded set would be excellent. I am really interested in a board/pair of boards (however the design progresses) for my Galaxy Saturn, great set... but a real traveller when the room temp changes!!

I'm sure that it could also be used to alter the coverage of other good SSB sets such as the 858's and clones such as Colonel/WKS/Stag/Palomar radio's. I don't know what its like is Aus, but getting tight tolerence xtals made to change ranges in the UK is becoming expensive.

Anyway, as always, a great read, please keep us informed as the "drift killer" progresses.

Thanks again.
Alan 26FB806
----------------------
27.385 LSB, 27.555 USB, 27.78125 FM

Use it or lose it!!!!

lbcomms
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Re: Finally stopped the Galaxy / ranger drifting

Post by lbcomms » 02 Nov 2019, 16:12

Replacing the VCO with a DDS or similar was tried, but in all cases it made the RF performance worse. They are not as clean spectrally as a VCO and these low level additional frequencies they generate can mix with incoming signals on frequencies other than what has been selected to receive and put them into the IF passband - in other words, increasing the noise and interference in your receiver.

They can be cleaned up with filtering, but it needs to be a filter with variable tuning to keep it as clean as a VCO. This needs stable, close tolerance components, read as expensive. Making the existing VCO more stable gives the same result for less money and effort, so we went that way.

The only time this doesn't apply is where there wasn't a VCO on the first place, such as the mid 70's 23 channel radios that used 10 to 14 crystals. These crystal synthesizers were fairly dirty to start with so the radios they are used in have tight filters in there already, to enable them to meet FCC specs. This also means they are limited to 80 channels tops if you want them to stay clean, which is not really and issue as most folk just want to put what would otherwise be a paperweight onto 35, 38, or 555 depending on where they are located.

Back to the PLL drifty radios, the add-on board will lock the existing VCO to a much more stable reference than the existing circuit, reducing the drift to the point where it can't be detected by ear. The last ones we bought were under 300ppb, which works out to "0.3 hertz per megahertz", so a 27 MHz radio will be stable to (27 x 0.3) worst case 8Hz, 0 to 60 degrees C. Most people can't detect a 25 hertz error by ear, so the transmission always sounds spot on.

The DIY version is 1500ppb (1.5 "hertz per megahertz"), so a 27 MHz radio will be stable to 40Hz. This is only just barely detectable by most people, and more than good enough for voice communications. On the upside, it uses off the shelf "ebay" parts and doesn't need any SMT soldering. Alignment of frequency and SSB offsets is done with an app, along with other options such as clarifier range and selecting whether the clarifier tracks transmit and receive or just operates on receive only.

To be continued...

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