Posted: 12/15/2014 1:25:37 AM EDT
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I want to add a frequency standard to my lab.
I'm torn between a Rubidium (RDO) and GPS (GPSDO) I don't do this stuff every day, but a more accurate time base would be very nice to have. seems the recent past availability of cheap RDO's on ebay are gone. the "retired" RDO's are still probably more accurate than any of the xco's in my gear, but the GPSDO's would maintain an accuracy as long as there were GPS satellites in orbit. anyone have any experience with building (or buying) one of them? I'll probably need a distribution amp for the signal, as I've got 5-6 devices that'll take the input. I think DEM has 'em. |
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I can only speak to the time part, I recently set up a time server that's accurate to 1-2 uS using ntp and a
PPS-enabled GPS unit, it's bordering on stupid easy to do. A side effect of this was letting me measure how good WWV is as a time base, and it's pretty darn good. If GPS ever goes down, having a reliable frequency standard in a home lab is going to be pretty low on the problems to solve list. 
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I've used many of both types in my work. These days I'd take an inexpensive GPSDO any day over a Rubidium unit. If you are looking at something new then the go-to places are Jackson Labs and Spectrum Instruments. I've bought inumerable TM-4's and they all work great.
There is a smokin' deal on eBay right now: http://www.ebay.com/itm/Intelligent-Reference-TM-4-GPS-Time-FREQ-Reference-Module-Spectrum-Inst-INC-/221584281776?pt=US_Radio_Comm_Meters&hash=item339773d0b0. If you want to hack just a little bit there are no end of old Trimble Thunderbolt units on eBay. Many of these have been pulled from older cellular base station installations. See http://www.leapsecond.com/tbolt-faq.htm. eta I'd love to connect one to my Flex 3000. The thing drifts like crazy! My IC7000 was better! But since there isn't an easy way to do that I'm holding off until I get an Anan 
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Quoted:
I've used many of both types in my work. These days I'd take an inexpensive GPSDO any day over a Rubidium unit. If you are looking at something new then the go-to places are Jackson Labs and Spectrum Instruments. I've bought inumerable TM-4's and they all work great. There is a smokin' deal on eBay right now: http://www.ebay.com/itm/Intelligent-Reference-TM-4-GPS-Time-FREQ-Reference-Module-Spectrum-Inst-INC-/221584281776?pt=US_Radio_Comm_Meters&hash=item339773d0b0. If you want to hack just a little bit there are no end of old Trimble Thunderbolt units on eBay. Many of these have been pulled from older cellular base station installations. See http://www.leapsecond.com/tbolt-faq.htm. eta I'd love to connect one to my Flex 3000. The thing drifts like crazy! My IC7000 was better! But since there isn't an easy way to do that I'm holding off until I get an Anan I am surprised the Flex 3000 doesn't have an input for an external reference oscillator. I had one on my Flex 1500. It was this one. The one that I bought looked in nicer condition than the one in that picture and is mounted on a PC board. The one I bought was also recently calibrated. I bought it from ebay, put it in a nice project box with power connector, bnc connector, fuse holder, power swtich and an LED to indicate that it was turned on. My Flex 1500 didn't drift, but it was cool to turn on WWV at 10 mhz, then switch on the reference oscillator and watch the radio snap over to exactly the WWV frequency. When I bougtht my Flex 6000 I got the optional GPS disciplined oscillator. I have no real use for this kind of frequency accuracy, but I think it is cool, so I bought them. Between the two, the GPS oscillator is definitely the way to go. Not that I know much about this subject or any other. |
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I have a GPSDO and they are the way to go.
I have the one from James Miller G3RUH, not cheap but plug and play. Look Here |
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I have a GPSDO and they are the way to go. I have the one from James Miller G3RUH, not cheap but plug and play. Look Here That looks like a nice GPSDO setup. If I didn't have a trimble thunderbolt I'd pull the trigger on one of these. |
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That looks like a nice GPSDO setup. If I didn't have a trimble thunderbolt I'd pull the trigger on one of these. Quoted:
Quoted:
I have a GPSDO and they are the way to go. I have the one from James Miller G3RUH, not cheap but plug and play. Look Here That looks like a nice GPSDO setup. If I didn't have a trimble thunderbolt I'd pull the trigger on one of these. I'm happy with it, I considered the Trimble Thunderbolt but at the time the price on them fairly high (for a used piece of gear with no warranty) made me look at what other options were available. |
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I have a GPSDO and they are the way to go. I have the one from James Miller G3RUH, not cheap but plug and play. Look Here looks decent, but at 436.365 USD...ouch |
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looks decent, but at 436.365 USD...ouch Quoted:
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I have a GPSDO and they are the way to go. I have the one from James Miller G3RUH, not cheap but plug and play. Look Here looks decent, but at 436.365 USD...ouch Yes but for that you get extreme accuracy |