Aha! Then I did not fully understand the inner workings of the K2. I just looked att the schematics and noticed the BFO and the mixer. Out of that I made the conclution that the BFO value must change the pitch.
So what you are saying is: During filter setup, it is normal for the pitch to change but when I press XFIL the save-routine inside the K2 is compensating for the change and restores the pitch to its original position? Is that correct? Which in practice means that I cannot adjust the pitch manually (like on an old radio), it's up to the K2 routine to set the pitch. ./Erik 2012/4/29 Don Wilhelm <[email protected]> > Erik, > > The K2 will preserve the pitch when the BFO is changed. Of course, if > you move the BFO enough, the signal will no longer be inside the passband. > > You must move the VFO to change the pitch, just changing the BFO will > not do it. The filter passband edges will change, but the pitch of a > tuned signal will not. That is why it is important to use a broadband > noise generator (often band noise will do) and some type of audio > spectrum analyzer (I use Spectrogram) to view the shape of the passband > - you can see when it is centered at your target pitch. Use no signals > in the passband when changing the filters, having signals present will > only confuse your view of the passband shape and positioning. > > If you need Spectrogram, you can find it on my website www.w3fpr.com - > look near the bottom of the opening page. > > 73, > Don W3FPR > > > On 4/29/2012 4:40 PM, Erik Linder wrote: > > Don, tnx for the answer. > > > > Yes, the difference was small. Tnx for the info about 20 Hz, then I now > the > > limitation of the construction. > > > > Yes I can use the FL1 (open) as both TX and RX (well of course TX is > alway > > using FL1). But if I want something more narrow I like to use FL2 - FL4. > > And now I know that I can get in 20 or so Hz if I work hard enough. :-) > > > > But the main problem here is that I cannot adjust my filters at all right > > now. :-( > > I can move the BFO (change the pitch) as long as I am in cal fil but as > > soon as I save the filter and return to listen the pitch has changed to > > "default". The BFO-value _has_ changed, it _has_ been saved. (I see the > > display showing BFO freq for a short time). > > But still - the pitch is where it was before I changed the BFO-value. > > > > And I have changed it much - like 50 to 100 units. USB, LSB, CW - the > mode > > does no difference. > > > > So: > > Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz > > The BFO value is (lets say) 128 > > I change the BFO value too 100 > > I hear (and see on the waterfall) that the pitch is changing. > > I press XFIL (to save) > > Display shows BFO freq for a short time. > > I press XFIL a couple of times to "get round" to FL1 again. > > The pitch has now jumped back to 1500 > > The BFO-value is at it's saved 100 > > > > I can now lower the BFO value once more and when I come around the pitch > > will be 1500 and the BFO is saved with the new value. > > > > Isn't it suppose to work like: > > Change the BFO to get the correct pitch > > Save > > Return to the filter and the pitch is where you programmed it to be. > > > ______________________________________________________________ > 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
