With so much discussion about GPSDO's, and the recent article in QST, I was wondering if the under $300 Bodnar GPS Disciplined Oscillator would be an acceptable substitute for the internal module for my 6500?
I am interested especially in whether it's phase noise content would be within tolerance so as not to compromise the excellent response of the 6000 series.
I am interested especially in whether it's phase noise content would be within tolerance so as not to compromise the excellent response of the 6000 series.
Posted 3 years ago
George Molnar, KF2T, Elmer
Like the Bodnar idea of dual, independent frequency outputs to lock my Flex AND transverter. Both have TCXO's now, but the thought of being just that much more stable for weak-signal work has its appeal. Would love to hear some real user reports!
Tim,
Any update for additional functionality for the GPSDO?
Any update for additional functionality for the GPSDO?
Tim - W4TME, Customer Experience Manager
Not at this time.
When is the 10MHz output active? Does the 6500 have to be powered on?
Tim - W4TME, Customer Experience Manager
It has to have power applied to it.
i run it on 2 432 222 lock radio and tranverter right on
Peter K1PGV, Elmer
Peter K1PGV, Elmer
Is this the unit being discussed?
http://www.ebay.com/itm/121530825744
Sure is reasonably priced. Does anyone have one?
Jon...kf2e
http://www.ebay.com/itm/121530825744
Sure is reasonably priced. Does anyone have one?
Jon...kf2e
Scroll up to the first post reply in the thread that i made i posted a couple of links for you to do some reading. I dont have a calibrated counter that goes to less than tenths of a hz but mine runs right with my rubidnium standard if i put em both on the scope. People have tested and givin the differences in those units.
Peter K1PGV, Elmer
If that replay was supposed to be to me (it's not clear).... We are discussing two different units.
My curiosity and questions were with respect to the commercial Bodnar unit being sold by Force-12 here is the States, not the BG7TBL from eBay.
Peter
K1PGV
My curiosity and questions were with respect to the commercial Bodnar unit being sold by Force-12 here is the States, not the BG7TBL from eBay.
Peter
K1PGV
George Molnar, KF2T, Elmer
Jon, I've heard of some good results with the eBay unit. He makes a number of variants, it seems. Sine wave 10 MHz seems to be a great deal for the Flex. If you need a second, different frequency output, though, the Bodnar seems like the ticket.
Got to say, though, the 6500 is pretty darn stable on its own. My XV144 with TCXO and some after-market styrofoam work seems to be quite good, too. +/- just a few Hz on 2m, once I got it netted to a known good source.
Got to say, though, the 6500 is pretty darn stable on its own. My XV144 with TCXO and some after-market styrofoam work seems to be quite good, too. +/- just a few Hz on 2m, once I got it netted to a known good source.
Ok I'm brand new to the Flex, (just took delivery yesterday.) I have one of these Bodnar units, and would like to use it to calibrate the radio.(6500) I plugged a feed over to the 10MHz in and clicked on calibrate, and it's still -550 or so. I'm sure I'm doing something wrong, any suggestions would be appreciated. The Bodnar is sync'ed and is spot on, I checked with my O-scope.
Joe. Did you ever get your Bodnar unit to calibrate close to 0 as one would expect and actually work. I'm having the same issue with mine. I have removed the power cord leaving it off for a while to assure power is off. I know the Bodbar works, as I confirmed with a friends Icome 7800 and K3
Paul Christensen, W9AC, Elmer
The higher-priced version of the Bodnar is still > 30 dB worse at a 100 Hz offset than a Trimble Thunderbolt with a Piezo-branded OCXO when powered from a low-noise, lab-grade supply. For example, typical Trimble PN at 100 Hz is -160 dBc. The upper-grade Bodnar unit is about -125 dBc.
Compared to what's available on the new and used markets, the Bodnar's performance is probably better characterized as good, but not excellent. For Flex users it may not be an issue, but if the device is driving other test gear, that 30 dB difference may mean a lot.
The Trimbles were once plentiful on eBay for USD $99. Scarcity has driven that up but with persistence, a watchful eye can still spot one for a reasonable price.
I ended up installing a Trimble unit and Lambda linear supply into a customized enclosure:
Paul, W9AC
(Edited)
KE5FX thinks the Trimble-branded OCXO's are the ones that perform to the specs you list, viz a viz, the Piezo. Also, note that those specs can only be reached if the Trimble OCXO is removed from the PCB.
It's hard to tell precisely, but the Piezo looks like it lands somewhere around -142dBc at 100Hz. I do wonder what it would have been if he had tested the Piezo after removing it from the PCB, which is how he tested the HP and Trimble.
Check the following link, especially near the bottom, under "October 24, 2011: Further notes on the Thunderbolt OCXO":
Paul Christensen, W9AC, Elmer
My error in reporting. Yes, I meant the Trimble-branded OCXO and not Piezo. I derived my data above from the Trimble-branded OCXO.
Even the Piezo model has a (roughly) 20 dB phase noise advantage at a 100 Hz offset over the precision Bodnar unit. A decade later and the Thunderbolt performance is still extraordinary when powered from a low-noise supply.
Look for Thunderbolt Rev. E units with a 2004 date code (or later) for the best chance of getting one with the Trimble OCXO.
Paul, W9AC
Even the Piezo model has a (roughly) 20 dB phase noise advantage at a 100 Hz offset over the precision Bodnar unit. A decade later and the Thunderbolt performance is still extraordinary when powered from a low-noise supply.
Look for Thunderbolt Rev. E units with a 2004 date code (or later) for the best chance of getting one with the Trimble OCXO.
Paul, W9AC
I am still unclear about how a Trimble or the internal GPSDO effects phase noise. Does this improve the radios phase noise or just frequency accuracy ?
Sorry. I'm digging up old threads to finish them off.
See https://community.flexradio.com/flexradio/topics/external-10-mhz-reference-phase-noise-requirements
For anything above a 20Hz bandwidth (i.e., negligible), Flex transceivers retain their own phase noise characteristics when using an external reference. Essentially, the external reference is only used for long term frequency accuracy.
For those interested, I just received the Bodnar GPSDO Phase Noise Plot from SDRKits.
Here is a copy for your review.
Tom W3FRG
Here is a copy for your review.
Tom W3FRG
