[Elecraft] Filter alignment question
Hi, I was monitoring the K2's local oscillator frequency and I noticed that as I tune to WWV in the various modes, that the LO frequency is different at zero beat. I expected an offset (w/respect to SSB) in the CW mode but I expected the LO to be the same at zero beat whether I was in LSB or USB modes. It isn't so I am wondering if something is not aligned properly. Any insight is appreciated. Thanks Mike, WA1SEO K2 4778 ___ 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
RE: [Elecraft] Filter alignment question
Mike, Which oscillator are you referring to as local Oscillator? If you are referring to the BFO, then it should be different from LSB to USB because that is the way the sidebands are switched. If you are referring to the VCO, then you must be retuning if that changes between LSB and USB - if there is a need to re-tune to maintain zero beat, then yes, a filter alignment is in order, and perhpas a dial calibration also. Full, detailed instructions for setting the reference oscillator and doing a dial calibration and filter alignment can be found on my website http://w3fpr.qrpradio.com 73, Don W3FPR -Original Message- I was monitoring the K2's local oscillator frequency and I noticed that as I tune to WWV in the various modes, that the LO frequency is different at zero beat. I expected an offset (w/respect to SSB) in the CW mode but I expected the LO to be the same at zero beat whether I was in LSB or USB modes. It isn't so I am wondering if something is not aligned properly. Any insight is appreciated. Thanks Mike, WA1SEO K2 4778 ___ 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
Re: [Elecraft] Filter alignment question
Hi Here is a way to check the alignment of the filters. Assuming a 600 Hz sidetone tune to 4.000 MHz in CW normal mode You should hear the 4 MHz internal oscillator as a 600 Hz tone, Switch to each filter and the tone should not change frequency by more than a few hertz. Then switch to CW reverse and go back through the filters. Again the 600 Hz tone should not change. To check the SSB filters select LSB and tune to 4.00060. You should hear the same 600 hertz tone then check each SSB filter and the tone should not change. Now change to USB and tune to 3.99940 MHz and check for the 600 hertz tone on each filter. If you do not hear the correct tone on any of the above tests then you need to recheck the filter alignment for that filter. You may have it set on the wrong side of the filter slope or may need to move it slightly. Use spectrogram to re-align the filters after first setting them to the values listed in the manual so they are in the ballpark. You should move each filters BFO frequency slightly even if it is correct so the firmware will recalculate the sidetone offsets. Don Brown KD5NDB - Original Message - From: [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Monday, March 13, 2006 7:05 AM Subject: [Elecraft] Filter alignment question Hi, I was monitoring the K2's local oscillator frequency and I noticed that as I tune to WWV in the various modes, that the LO frequency is different at zero beat. I expected an offset (w/respect to SSB) in the CW mode but I expected the LO to be the same at zero beat whether I was in LSB or USB modes. It isn't so I am wondering if something is not aligned properly. Any insight is appreciated. Thanks Mike, WA1SEO K2 4778 ___ 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 ___ 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
Re: [Elecraft] filter alignment question
W3FPR - Don Wilhelm wrote: If the tone pitch change is 20 Hz or less it is because of the quantizing error in the K2 and nothing can be done about it. The K2 firmware works to preserve the pitch no matter where the filters are set as long as the signal is anywhere within the filter passband. Well, something CAN be done about it, if you don't mind changing the filter bandwidth slightly. For example, suppose that you have set a filter to 400 Hz bandwidth and located the BFO so that the signal is centered in the filter, and suppose that the result is that the pitch of the centered signal comes out 10 Hz. high. Just change the bandwidth to 420 (or 380) Hz., readjust the BFO and let the K2's magic algorithm do its work. Chances are it will come out on pitch. I have been able to adjust all of my filters so that there is no change in pitch when I cycle through them. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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
[Elecraft] filter alignment question
I recently acquired K2 #1084 from a friend. I upgraded the radio to Rev. B, added the DSP module and am about half way through the KPA100. As I was aligning the filters I noticed something unexpected. Everything seems to be fine except that as I scroll through the CW XFIL filters, the tone of the test signal changes slightly. Is this to be expected? Is it possible to get the tone exactly the same for every filter setting or is a slight variation normal? The DSP was in bypass while alignment on the XFIL filters was done. The K2 is a wonderful little radio. It sits on top of an OMNI 6+. Its a tough decision lately which one to use, hi hi. ___ 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
RE: [Elecraft] filter alignment question
If the tone pitch change is 20 Hz or less it is because of the quantizing error in the K2 and nothing can be done about it. The K2 firmware works to preserve the pitch no matter where the filters are set as long as the signal is anywhere within the filter passband. 73, Don W3FPR -Original Message- I recently acquired K2 #1084 from a friend. I upgraded the radio to Rev. B, added the DSP module and am about half way through the KPA100. As I was aligning the filters I noticed something unexpected. Everything seems to be fine except that as I scroll through the CW XFIL filters, the tone of the test signal changes slightly. Is this to be expected? Is it possible to get the tone exactly the same for every filter setting or is a slight variation normal? The DSP was in bypass while alignment on the XFIL filters was done. The K2 is a wonderful little radio. It sits on top of an OMNI 6+. Its a tough decision lately which one to use, hi hi. ___ 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
RE: [Elecraft] filter alignment question
KT5D asked: Everything seems to be fine except that as I scroll through the CW XFIL filters, the tone of the test signal changes slightly. Is this to be expected? Is it possible to get the tone exactly the same for every filter setting or is a slight variation normal? Yes, it is normal to have a slight variation although sometimes you get lucky and it will be zero. What's happening is that when you select a filter (FL1thru 4) digital data is being recalled from memory that is converted into an analog voltage that tunes the BFO and VFO to the right frequencies. The accuracy with which the analog voltage is generated is limited by the Digital-to-Analog Converters (DACs). The DACs in the K2 provide a resolution of about 30 Hz. That is, the frequency can be as much as 30 Hz different from the value that was originally set when the filters were aligned. What you need to do to get it closer, if you can, is to repeat the filter alignment procedure in the manual. Actually, you don't need to repeat the whole setup, but simply cause the system to re-store new digital data for the current settings. Information on now to do this is included in the Builders Resources on the Elecraft web site. You may get a closer match or, if you are already within 30 Hz, it might not be quite as good! Ron AC7AC ___ 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
