http://elecraft.85.s1.nabble.com/K3EXREF-and-Trimble-Thunderbolts-tp6242158p6242822.html
I should have added that USD $70 was the offered and accepted price.
> ----- Original Message -----
> From: "Matt Zilmer" <
[hidden email]>
> To: "Paul Christensen" <
[hidden email]>
> Cc: <
[hidden email]>
> 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
>>
>>
>>
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