I should have added that USD $70 was the offered and accepted price. Shipping was very fast as well.
> ----- Original Message ----- > From: "Matt Zilmer" <[email protected]> > To: "Paul Christensen" <[email protected]> > Cc: <[email protected]> > Sent: Tuesday, April 05, 2011 11:40 AM > Subject: Re: [Elecraft] K3EXREF and Trimble Thunderbolts > > > Thanks Paul. Good summary and reference info. > > The K3EXREF certainly works as advertised. I've already used two > different Rb sources, and it's solid as a rock. Using a TIA over the > weekend,, saw a 1 to 2 Hz wander at 28MHz, however the Rb clocks have > a little start-up drift and the wander might have been due to that. > And of course, the TIA is based on Rb, itself. > > I bought a Rev E Thunderbolt GPS-DO from a vendor on eBay. It's still > training (< 24 hours), and there was a 1 Hz per 10 minutes upward > drift after two hours of operation, in the REF*CAL indicator. Is this > normal? Will check it again at around 24 hours into the experiement. > Even though I work in the GPS industry, I've never used a GPS-DO > before. > > I've tossed my original Wellnav OCXO-based freq source. We use these > as a time base here in our GPS simulators, but they're far from phase > noise free and there is significantly more drift (might also be age). > Was seening 5 to 6 Hz of wander, and sampling it showed a textbook > [but skewed] Gaussian distribution. The wander should not generally > even be detectable with conventional ham equipment, but it was. > > Cool stuff. > > Just to reinforce Paul's comments, the Trimble software is quite > impressive. I work in the industry, and I've never seen even in our > own Pro products, so much monitored statistical and operations data in > a control program. It certainly was worth the price (see Trimble's > web site under Support). Free that is. > > I'm running the Tbolt on a linear supply. It's a three-output Topward > lab-grade PS. Monitoring the current consumed, I see the following: > +12V: 700-750 mA for startup (warming the OCXO), 40-50 mA steady state > -12V: < 20 mA continuous > +5V: 370 mA continuous > > Add all this up, and steady state power consumed comes to about 2.7W. > This is perfect for use in a solar-powered station. My K3 and general > station power comes from two 50W Siemens PV panels on the roof. These > feed a charge controller and 110AH 12V AGM battery in the shack. The > lower power consumption of the GPS-DO is compatible with this set up. > > I had borrowed a Brandywine unit from a buddy that works there, and it > consumed about 35W steady state. Not good for this installation. > > 73, > matt W6NIA > Upland, CA. > > On Tue, 05 Apr 2011 08:43:46 -0400, you wrote: > >>Those of you considering a GPS-disciplined oscillator for use with the >>K3EXREF may be interested in this: I recently purchased two Trimble >>Thunderbolts on the surplus market to compare against my HP 58540A and >>Brandywine GPS4 units. After several days of testing, I'm retiring the HP >>and Brandywine units. All devices have exceptionally good stability, but >>the Trimble units consume far less power, run substantially cooler, and >>the >>monitoring interface provides much more status information than the prior >>units. >> >>In recent discussions with John, KE5FX, he has performed phase noise >>measurements across several GPS-DO units and even various oscillator >>brands >>within the Trimble Thunderbolt model. >> >>http://www.thegleam.com/ke5fx/tbolt.htm >> >>Early Thunderbolts use a Piezo Corp. OCXO and when combined with GPS >>correction, its phase noise performance is good but not exceptional. By >>contrast, the Trimble-branded OCXO offers phase noise performance several >>degrees better than most other GPS-DO units near Fc. The area between 1 >>Hz >>and 100 Hz is usually a good indicator of the overall phase noise >>performance. It's not easy getting good numbers that distance from Fc. >>Although the phase noise performance will not carry over to the K3, it's >>an >>important parameter if the GPS-DO will be used in other applications or >>other transceivers that phase lock onto the 10 MHz external reference. >> >>Some suggestions: >> >>1) Look for Thunderbolts with a year 2004 Rev. E stamp. These use the >>better quality OCXO units with the Trimble-branded label. KE5FX has >>sampled >>several from this batch. As noted, early units with the Piezo-branded >>OCXO >>are worse in terms of phase noise performance. I do not know the OCXO >>quality of recent units; >> >>2) You will see Thunderbolts in a high quality case where an internal >>DC-DC >>converter is used. My recommendation is to avoid being tempted by the >>nice >>looks and what may be perceived as a "better" unit. I can almost >>guarantee >>that the switch-mode converters will present noise problems with your K3 >>receiver -- and seen on your panadapters. I've been down that road with >>other GPS-DO units and ultimately, I scrapped the converters and fed them >>with linear supplies. Stick to the basic ugly OEM Thunderbolt module and >>feed it from a triple-output linear supply; >> >>3) Power supplies: I like OEM/off-board supplies by PowerOne, Condor, and >>International Power. They offer excellent performance and low noise. I >>am >>using an International Power IHBAA-40W. Also look for HBAA-40W. The user >>must add a fuse, power cord and wiring harness. It's a little more work, >>but you get a lot of performance for the money; >> >>4) Look for sellers who will accept offers. Both my Thunderbolts were >>purchased for USD $70 ea and a small shipping change. >> >>Even if you have no plans to use K3EXREF, get one anyway as a precision >>frequency reference for your station. >> >>Paul, W9AC >> >> >> >>______________________________________________________________ >>Elecraft mailing list >>Home: http://mailman.qth.net/mailman/listinfo/elecraft >>Help: http://mailman.qth.net/mmfaq.htm >>Post: mailto:[email protected] >> >>This list hosted by: http://www.qsl.net >>Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
