Good frequency standard - UK Vintage Radio Repair and Restoration Discussion Forum

Wendymott · 2nd Apr 2018, 3:11 pm

Hi peeps. Have any of our members got a circuit for a decent 10 Mhz "off air" frequency standard please.
There are various ones on the "inter web" but none I would consider. The best guarantee is that a member has built one and can recommend it.
When I say "off air" it can be the 198Khz transmission.
I found a GPS one, but the modules were not now available.

Craig Sawyers · 2nd Apr 2018, 3:34 pm

I use a Trimble Thunderbolt GPS disciplined oscillator. The sell on eBay for a couple of hundred. Trimble bullet antenna on the end gable, and a cheapo switched mode supply and you are up and running.

chriswood1900 · 2nd Apr 2018, 4:08 pm

This thread had some info that may help and there was a Radcom arcticle many years ago and some kits that followed it.
https://vintage-radio.net/forum/showthread.php?t=137735
Chris

chriswood1900 · 2nd Apr 2018, 4:27 pm

Just found this.
http://www.qsl.net/pa2ohh/07freqstd.htm
and
http://www.g4jnt.com/MSFPart1.pdf
and
https://www.epemag3.com/lib/free_pro...0Generator.pdf
and this
http://www.spectrumcomms.co.uk/Test.htm
Last but one item.
Also take a look at the commercial units like the Quartlock 2A the manual is available here http://www.quartzlock.com/userfiles/...%20Scanned.pdf.
Good luck
Chris

jimmc101 · 2nd Apr 2018, 8:19 pm

If you don't mind a bit of experimenting and are on a budget I would suggest looking at James Miller's design.
The Jupiter-T module is long gone but there are some cheap modules on ebay using U-blox devices that should do the job (but watch the logic levels)...
The older (and cheaper - £3.50 with aerial) NEO-6M can be programmed to output a timepulse frequency of 1Hz to 1kHz. This is brought out to a pin on the v2 boards.
The newer NEO-7M can do 1Hz to 10MHz. (£5.50 without aerial)

Neither are meant for timing applications and will have a lot of jitter on their output but with a PLL to clean them up should be OK.
They might need something like an Arduino pro mini to program them at power-up, I'm not sure, and for less than £1.50 I'd use one anyway and use it to drive a status indicator LED.

I built a similar GPSDO about 7 years ago along these lines using a much older U-blox CW25 module which worked well.

You do need to be able to 'see' the satellites, an outdoor aerial is ideal but indoors on a windowsill works in a lot of places.

Jim

Nymrod121 · 2nd Apr 2018, 9:31 pm

Quote:

Originally Posted by Wendymott

Hi peeps. Have any of our members got a circuit for a decent 10 Mhz "off air" frequency standard please.

It depends on what you consider as 'decent'; for example, I have an ex-HP 10MHz OCXO unit that I've adjusted (albeit by a slightly complicated method) to be accurate to 1 beat cycle every 50 seconds with respect to a GPS-disciplined broadcast carrier frequency... would that qualify?
Best wishes
Guy

MrBungle · 2nd Apr 2018, 11:21 pm

I've got one of these on the "TODO list". It's a signal generator kit with optional OCXO and GPS module kits:

https://www.qrp-labs.com/vfo.html

Works out at $72 without enclosure.

There's an AN for it which shows how to add LPF modules to built a 0-30MHz low distortion generator: https://www.qrp-labs.com/images/appnotes/AN006_A4.pdf

I recently built one of their QCX kits and they're top notch. I can't vouch for the above (yet) but I'm willing to risk it soon

3rd Apr 2018, 10:47 am

The UBLOX SAM-8Q GPS module has a programmable timepulse pin. Worth reading the datasheets.

Wendymott · 3rd Apr 2018, 12:55 pm

Well. peeps..... Many thanks for the interaction..... lots to think about and try..I will keep you posted.

mhennessy · 3rd Apr 2018, 6:34 pm

Here's one built by our own Pamphonica:

http://golbornevintageradio.co.uk/fo...d.php?tid=5507

I'm quite tempted...

2nd Apr 2018, 3:11 pm	#1
Wendymott Octode Join Date: Jun 2013 Location: Huddersfield, West Yorkshire, UK. Posts: 1,795	Good frequency standard Hi peeps. Have any of our members got a circuit for a decent 10 Mhz "off air" frequency standard please. There are various ones on the "inter web" but none I would consider. The best guarantee is that a member has built one and can recommend it. When I say "off air" it can be the 198Khz transmission. I found a GPS one, but the modules were not now available. __________________ Should get out more. Regards Wendy G8BZY

2nd Apr 2018, 3:34 pm	#2
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,996	Re: Good frequency standard I use a Trimble Thunderbolt GPS disciplined oscillator. The sell on eBay for a couple of hundred. Trimble bullet antenna on the end gable, and a cheapo switched mode supply and you are up and running.

2nd Apr 2018, 4:08 pm	#3
chriswood1900 Octode Join Date: Jan 2007 Location: Dorridge, West Midlands, UK. Posts: 1,486	Re: Good frequency standard This thread had some info that may help and there was a Radcom arcticle many years ago and some kits that followed it. https://vintage-radio.net/forum/showthread.php?t=137735 Chris

2nd Apr 2018, 4:27 pm	#4
chriswood1900 Octode Join Date: Jan 2007 Location: Dorridge, West Midlands, UK. Posts: 1,486	Re: Good frequency standard Just found this. http://www.qsl.net/pa2ohh/07freqstd.htm and http://www.g4jnt.com/MSFPart1.pdf and https://www.epemag3.com/lib/free_pro...0Generator.pdf and this http://www.spectrumcomms.co.uk/Test.htm Last but one item. Also take a look at the commercial units like the Quartlock 2A the manual is available here http://www.quartzlock.com/userfiles/...%20Scanned.pdf. Good luck Chris Last edited by chriswood1900; 2nd Apr 2018 at 4:44 pm. Reason: Typo

2nd Apr 2018, 8:19 pm	#5
jimmc101 Heptode Join Date: Mar 2009 Location: Portsmouth, Hampshire, UK. Posts: 674	Re: Good frequency standard If you don't mind a bit of experimenting and are on a budget I would suggest looking at James Miller's design. The Jupiter-T module is long gone but there are some cheap modules on ebay using U-blox devices that should do the job (but watch the logic levels)... The older (and cheaper - £3.50 with aerial) NEO-6M can be programmed to output a timepulse frequency of 1Hz to 1kHz. This is brought out to a pin on the v2 boards. The newer NEO-7M can do 1Hz to 10MHz. (£5.50 without aerial) Neither are meant for timing applications and will have a lot of jitter on their output but with a PLL to clean them up should be OK. They might need something like an Arduino pro mini to program them at power-up, I'm not sure, and for less than £1.50 I'd use one anyway and use it to drive a status indicator LED. I built a similar GPSDO about 7 years ago along these lines using a much older U-blox CW25 module which worked well. You do need to be able to 'see' the satellites, an outdoor aerial is ideal but indoors on a windowsill works in a lot of places. Jim

2nd Apr 2018, 11:21 pm	#7
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Good frequency standard I've got one of these on the "TODO list". It's a signal generator kit with optional OCXO and GPS module kits: https://www.qrp-labs.com/vfo.html Works out at $72 without enclosure. There's an AN for it which shows how to add LPF modules to built a 0-30MHz low distortion generator: https://www.qrp-labs.com/images/appnotes/AN006_A4.pdf I recently built one of their QCX kits and they're top notch. I can't vouch for the above (yet) but I'm willing to risk it soon

3rd Apr 2018, 10:47 am	#8
Guest Guest Posts: n/a	Re: Good frequency standard The UBLOX SAM-8Q GPS module has a programmable timepulse pin. Worth reading the datasheets.

3rd Apr 2018, 12:55 pm	#9
Wendymott Octode Join Date: Jun 2013 Location: Huddersfield, West Yorkshire, UK. Posts: 1,795	Re: Good frequency standard Well. peeps..... Many thanks for the interaction..... lots to think about and try..I will keep you posted. __________________ Should get out more. Regards Wendy G8BZY

3rd Apr 2018, 6:34 pm	#10
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Good frequency standard Here's one built by our own Pamphonica: http://golbornevintageradio.co.uk/fo...d.php?tid=5507 I'm quite tempted...