Rick, For the majority who only do CW/SSB on HF, adding the EXREF is probably unnecessary. The TCXO-3 holds the K3 within 14-Hz on 28-MHz. The EXREF improves that by an order of magnitude to 1.4 Hz.
This becomes necessary for some digital modes like JT-65. That is mainly used on eme on 144 and higher bands. If you operate on the microwave bands oscillator error is mulitplied so that is becomes hard to get much freq. accuracy or stability. On 1296 I use a transverter that has an external locked PLL LO. That keeps it within 1-Hz. Typically one would not have better than a few KHz with a xtal oscillator on 105.67 MHz multiplied x12 = 1268 MHz. Getting the accuracy on the transverter LO without also having it on 28-MHz IF radio is kind of being only "Half-done". With the K3 EXREF my combined 1296 freq. will equal that of the K3. That is important when eme signals are so weak they cannot be detected by ear. Add frequency errors to that and the task becomes very tough. Now consider doing that at 10-GHz. A few of us with K3's are mw'ers and/or eme'rs so the accuracy is very important to us. Sidenote: Use of 10-MHz WWV is nearly impossible if you run a 10-MHz station reference oscillator. I have a mw freq.counter that uses a rubidium external reference. I use it to check the frequency of my 10-MHz OCXO which I run thru a 4-way distribution amp to feed things in the shack: 1) K3EXTREF 2) 144/28 Transverter (DEMI) 3) 1296/28 Transverter (DEMI) 4) future item The OCXO was bought off e-bay for $39.99+shipping, and is very stabile but does drift over months so I "tweak" it back to the Rubidium about 4 times a year. It runs 24/7 on a battery supply floated by a charger. All can be seen on my website (including newly added instructions for adding sub-Rx IF Out). 73, Ed - KL7UW ------------------------------ Message: 33 Date: Sun, 20 Mar 2011 14:45:59 +0000 From: Rick Stealey <rstea...@hotmail.com> Subject: Re: [Elecraft] Installed K3EXREF To: <elecraft@mailman.qth.net> Excellent posting by W9AC, a great reference, to be saved. Now I wonder if it would be possible for someone to enlighten me as to the need for such extreme accuracy? Is it because my K3 reads out to 1 Hz but I can't really believe the absolute accuracy of that number unless I get a K3EXREF? But if that is the case, my question would still remain, wouldn't it? Not that I need something else to put on my list ahead of my P3 and sub receiver. Rick K2XT 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-1.4kw, 432-100w, 1296-testing*, 3400-winter? DUBUS Magazine USA Rep dubus...@hotmail.com ====================================== ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
