Brilliant - thanks to all for your replies. I'll start looking for a used Thunderbolt to experiment with. Sorry if I missed this in an earlier exchange, but are there specific Trimble model numbers known for recommended units?
Paul - I agree; can never hurt to have a disciplined reference source for other projects. Mni tnx es vy 73, James K2QI On Tue, Apr 5, 2011 at 3:40 PM, Paul Christensen <[email protected]> wrote: > Jim, > > In case you missed earlier comments, don't worry about phase noise > performance of the external reference if you'll only use it with the K3. > But, in addition to the K3, a high performance, low phase noise external > reference can be distributed around the shack or work bench for other > purposes. I use a second output from the Trimble to phase-lock an ADAT > transceiver. > > Paul, W9AC > > ----- Original Message ----- > From: "Paul Christensen" <[email protected]> > To: <[email protected]> > Sent: Tuesday, April 05, 2011 3:36 PM > Subject: Re: [Elecraft] K3EXREF and Trimble Thunderbolts > > >>> 1. Any reference oscillator operating at 10 MHz would work with the >>> K3XREF? >> >> The 10 MHz source should have a signal level between +4 dBm and +16 dBm. >> For >> square wave sources, 2VDC to 3.3VDC peak is optimum. If the source is a >> 5V >> logic level, use a 50-ohm resistor in series with the input. >> >>> 2. All that's needed for this to work is the K3XREF, updated >> firmware, an accurate 10 MHz clock/oscillator, and a BNC cable? >> >> Yes. >> >>> 3. Trimble Thunderbolt seems to be a good, cheap product to try. Any >> others that are > $100? >> >> Many. For those not affraid of getting a soldering iron hot, I think the >> Trimble units are pretty tough to beat. Requires making a power cable to >> a >> triple-output power supply of your choice. For a while, the HP Z3801A >> units >> were very popular. These use noisy DC-DC internal converters, are power >> hungry, but offer some of the best phase noise peformance of all the >> GPS-DO >> units. The Trimble units have been documented to pretty much meet the >> phase >> noise performance of the Z3801A. Rubidium is another choice in the USD >> $100 range but these too will require some creative power connections. >> >>> What are the additional advantages of doing this other than knowing >> you've pretty much eliminated any frequency drift? >> >> Really none I can think of, but as the weak-signal V/UHF ops have said, >> that's reason enough! >> >> 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 > -- 73 de James K2QI President UNARC/4U1UN ______________________________________________________________ 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
