Hi everyone, Lyle reminded me that the K3's built-in AF voltmeter display can be used as a reliable indicator of audio amplitude - it is a true RMS reading indication. He also indicated that a steady carrier can easily be used rather than the wideband noise source. If you use an on-the-air signal, be careful not to confuse amplitude changes caused by the filter with QSB on the signal. A QRP transmitter feeding a dummy load would probably serve as a steady source of carrier if you do not have a signal generator available.
There are several ways to do a relative gain evaluation, and I mentioned only the way I am more used to using - I just didn't think of the others initially. 73, Don W3FPR -------- Original Message -------- Subject: Re: [Elecraft] SHIFT pitch Date: Tue, 27 Jan 2009 11:06:20 -0500 From: Don Wilhelm <w3...@embarqmail.com> Reply-To: d...@w3fpr.com To: W5UN <w...@wt.net> CC: elecraft@mailman.qth.net References: <20090127073502.f72f4...@dm0205.mta.everyone.net> I suspect that the filter gain rather than the width is the major cause of that behavior. Try working with the FLx GN setting in the CONFIG menu to see if you can obtain a smoother transition. You could expect the widest filter to have the smallest loss, so start with the transition between FL1 and FL2 and when that seems right, move on to the FL2 and FL2 transition, etc. The easiest way to do this is with a broadband noise generator (such as the Elecraft NGen) so you have a constant input to the K3 and it would be easy to evaluate the audio level using Spectrogram or some other audio spectrum analyzer, although a AC DMM connected across the speaker would give decent results. Once you have the filter gains equalized, you can easily change the filter offsets if necessary. While the 8 pole filter offsets are close to zero, it is not practical to expect that they are all exactly zero. 73, Don W3FPR W5UN wrote: > I have three 8 pole filters installed, 2.8, 1.8, and .4 kHz. As I > rotate the WIDTH knob, the filters switch in and out at their > transition frequencies (as they should). But when that switch occurs, > the background noise pitch frequency seems to jump to a different > SHIFT frequency setting. In other words, the transition between > filters is not smooth. > > I am wondering if all K3's with 8 pole filters do the same thing as mine? > > My filter offsets are all set to zero, as that is what I am told the > 8 pole filters offsets should be. > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
