Ebay Frequency Standards-Rhubidium and OCXO

Discussion in 'Homebrew and Kit Projects' started by K9TW, Mar 13, 2012.

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  1. K9TW

    K9TW Ham Member QRZ Page

    I am thinking about buying either a OCXO or a Rhubidium frequency standard for use as time base for my service bench frequency counters and signal generators. I am going to Dayton Hamfest and hope to find something there. If not, I have been looking on Ebay and see couple of Chinese suppliers of both types of 10 Mhz standards. Does anyone have any experience buying from these suppliers?

    I see the OCXOs are at least half the price of the Rhubidiums. I dont want to get too anal about this and not ready to look at GPS based units at this time.

    Any counsel would be appreciated as to which standard to buy and if there is one Ebay dealer more reputable than another.

    Thanks
    Terry K9TW
     
  2. KD0CAC

    KD0CAC Ham Member QRZ Page

    I have come across a lot of activity about those recently , maybe some upgrading has hit the surplus market as I remember , looking into the same .
    Some groups I have been monitoring this subject with have been ,
    TimeNuts
    Hackaday
    EEVblog
    and a local Ghz guy NLRS , Northern Lights Radio Society
     
  3. WA6TKD

    WA6TKD Ham Member QRZ Page

    I would think that a OCXO would be more then sufficient as a local 'bench standard'. Those Rubidium frequency standards are impressive but are more complex with certain components with finite lifespans, they just have more to go wrong in them. They are pulls from older cell phone equipment that have been upgraded or replaced. If you do go with a 10Mhz OCXO be sure you get the output type you want, sine-wave or square-wave.
     
  4. G0HZU

    G0HZU QRZ Member

    I recently bought an item from (chinese) ebay seller 2010bluebook who also sells the rubidium standards.

    My item was an Anritsu N type 50 ohm termination (12GHz) and it was sent on free delivery for $25.

    I was a bit worried at first (because it was such good value) but the item arrived three weeks later as described and it tests out fine on a microwave VNA. You also get a tiny free toy doll/bear with the sale and I think it's to do with the chinese customs as the parts are marked as used ham radio items when they arrive and the parcel has various stickers on it to do with export control and customs etc.

    The ebayer seems VERY keen to maintain good feedback and includes a letter with the item to reflect this so I think this seller is OK :)
     
  5. G0HZU

    G0HZU QRZ Member

    Personally, I'd go for the rubidium standard as the OCXO specs from the same vendor are very good but not 'fantastic' by today's standards.

    eg I have various frequency standards here and one is very similar to the Isotemp part. Mine is 5 parts per billion over -20 to +70degC (Quintenz) and it is nearly 10yrs old.


    However, it's the ageing spec that is most critical and mine does need a minor adjustment every year or so when measured against an offair standard. I'm tempted to go for a GPS based standard once the local offair (198kHz) transmitter at Droitwich shuts down in the near future. About 15yrs ago I designed and built my own 10MHz offair standard to lock to this local transmitter and pretty soon it is going to be redundant as they are running on their last set of transmitter tubes...

    http://en.wikipedia.org/wiki/Droitwich_transmitting_station
     
  6. K9TW

    K9TW Ham Member QRZ Page

    Thanks to all this is exactly info I was hoping for. I did see the bluebook seller. Also, I had not thought about sine vs square wave output. I had never heard of Droitwich very interesting.

    I will wait and see how I can do at Dayton on either type unit. If no go there then will have to decide on OCXO vs Rhubidium and take my chances on Ebay. Probably should have gotten the Rhubidium several years ago when they were half or less of going price today.

    I saw a Thunderbolt GPS unit on QTH not long ago, but it was $300 and I dont want to get that much involved. Tnx and 73s Terry
     
  7. LU1AR

    LU1AR Ham Member QRZ Page

    I bought a Rubidium Standard and was received with free delivery to Argentina (ยก!). They need 18 VDC 2 A. peak, 900 mA running and 5 VDC 300 mA. After warming inside, give negative a logic state. I used to light a LED, conected to the +5VDC line.
    The unit is surplus from Cellphone base stations and run OK. You will have a privillege to use a Rubidium Standard in your shack.
    Any trouble related with aging is no significative in the environment of amateur use. The worst Rubidium Standard is an order of magnitude better than the best OCXO.
    Regards.
    Edgardo
     
  8. W9GB

    W9GB Ham Member QRZ Page

    Terry -

    You don't need to spend that much.
    I have a Thunderbolt GPS unit here, if you wanted one badly.

    w9gb
     
  9. WA7PRC

    WA7PRC Premium Subscriber QRZ Page

    Like Edgardo/LU1AR, I recently purchased a used Frequency Electronics pn FE-5680A rubidium standard from eBay... less than $50 including shipping. While the datasheet says it wants 15 to 17VDC, it runs fine on 13.8V. It also needs 5VDC. Output is sinewave 10MHz @ +7dBm.

    I plan to use it with my TS-850S and an interface that also came from eBay. The interface is an active doubler. Its current monitor will tell the TS850 whether to use the internal or external reference. I'm way ahead of buying a TCXO, in terms of both cost and precision. :)
     
  10. K9TW

    K9TW Ham Member QRZ Page

    I sent you a response to your ARRL.Net email address to discuss this off list. My email is wagstw46@aol.com. Thanks Terry
     
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