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
