HI Wayne, I have also noticed about the same TX power fluctuation when running JT65B with the K3 + XV-144 and attributed it to the filter variations. Normally 20% isn't much of a problem, but when working a very weak signal mode like JT65B having the tones vary 1.5 db could make a significant difference in decoding a sequence or not. In my case, full power output occurs at the lowest tone (1270 Hz) declining to about 20% lower at the highest tone (~1625 Hz). I believe the ability to accurately compensate at the DSP's IF would be a valuable addition.
73 Joe N6KK PS. I didn't mention it, but I LOVE THIS RIG! ----- Original Message ----- From: "wayne burdick" <n...@elecraft.com> To: <gliderboy1...@yahoo.com> Cc: <elecraft@mailman.qth.net> Sent: Sunday, March 08, 2009 10:15 PM Subject: Re: [Elecraft] K3 + XV-144 use on EME > > On Mar 8, 2009, at 9:23 PM, eric norris wrote: > >> This weekend I put my new K3 + XV-144 on EME using JT65 for the first >> time. I have these questions: >> >> 1. Using USB, I got a 20% TX power fluctuation depending on the tone >> being sent. > > Hi Eric, > > The K3's 8-pole, 2.8 kHz filter has typically less than +/- 1 dB > ripple. The 5-pole 2.7-kHz filter can be higher. "20%" power > fluctuation is only 1.5 dB, so this could entirely account for what > you're seeing. It may be possible to compensate using TX EQ, but it > would be more accurate to compensate directly at the DSP's IF, which is > on our list for future consideration. > > Does the present amount of amplitude variation affect JT65's accuracy? > >> >> 2. The first station I worked off the moon reported my TX signal >> being abt 600 Hz high. My XV-144 has the xtal oven and had been on >> for an hour before I got on the air. I was able to dial this in using >> XVTR OFFSET, but I had to set it to +600 to move the signal down >> 600Hz. Shouldn't this work the opposite way? > > Yes. In the XVn OFS menu entry, you're telling the K3 how far off your > transverter is, and in what direction. The K3 compensates the VFO for > this. > >> >> 3. While monkeying with the XVTR OFFSET, both VFOs locked on the K3, >> every time I would change the parameter and exit the menu VFO A would >> be set to 144.200, and the preamp would be on when I had turned it off >> and set the attenuator. Is this a possible firmware issue? > > Maybe. Please give me the exact series of K3 switch/knob events so I > can try to duplicate it. > >> Did I mention I LOVE THIS RIG! > > Yes :) > > Thanks! > > 73, > Wayne > N6KR > > --- > > http://www.elecraft.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 > ______________________________________________________________ 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
