+++++++++++++++++++++++++++++++++++++++++++++++ From: Wayne Burdick To: "Randy Moore" I had a talk with Eric about your problem. I misunderstood your situation: I thought you were using the spectrogram program to plot the center frequency of the *noise* output of the RX--I didn't realize you were using a carrier and tracking its pitch, which the K2 will preserve regardless of how you move the BFO! I can assure you that what you're experiencing is not related to the firmware rev., by the way. An example may help: - - VFO dial 7000.0 - - XFIL 4913.6 (center of xtal filter at present bandwidth) - - Sig gen 7000.0 - - BFO 4913.1 - - Sidetone 0.6 - - VCO 11913.7 (VFO + BFO + sidetone) The signal generator's carrier is not quite centered in the filter passband with the present setup -- it's 100 Hz too high: 11913.7 - 7000.0 = 4913.7 = IF carrier freq. But you'll hear the signal at a 600 Hz pitch because that's where you have the sidetone set (BFO - IF): abs( 4913.1 - 4913.7 ) = 0.6 kHz What happens when you run CAL PLL and move the CW-N BFO down 100 Hz to 4913.0? The new VCO value is calculated as soon as you switch filters or modes (in your case, you moved from CW-N to CW-R, then back again): VCO = 7000 + 4913.0 + 0.6 = 11913.6 The IF carrier signal now *is* centered in the filter passband, which is the desired result: 11913.6 - 7000.0 = 4913.6 = new IF carrier freq. BUT, you still hear it at 600 Hz: abs( 4913.0 - 4913.6 ) = 0.6 khz So what we've done is to move the signal in relation to the filter, while *preserving* pitch. (This is similar to IF shift on other radios.) No matter how far you move the BFO, this will always be the case. Hence your spectrogram program will think the signal has not moved--although it *will* be better centered in the crystal filter passband, at least if you've correctly determined what the center frequency of the filter is. You can now move your signal generator or the K2's VFO around a bit to check if the filter center corresponds to the desired pitch. Actually, if you can find the filter center frequency at each bandwidth used (using the "zero-pitch" method), you can then just set the CW-N and CW-R BFOs directly to Fcenter - sidetone and Fcenter + sidetone. That's why we added the BFO DISPLAY mode to CAL FIL. HOWEVER, the bigger problems are still (1) the counter's quantization error, and (2) a small amount of drift with temperature. No matter how much you tweak the BFO, you'll potentially always be off by as much as the sum of these two. I hope this helps! You can see why we don't try to explain this in *too* much detail in the manual. 73, Wayne ++++++++++++++++++++++++++++++++++++++++++++++++ Date: Sat, 05 Jan 2002 21:33:39 -0600 To: Peter Lutz AA6AV , elecraft at mailman.qth.net From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] Cal Fil possibilities in the K2 Peter: >Since I now have all the options of interest in my K2, I want to make sure >the filter calibrations are "correct", or at least as good as can be. I have >been experimenting with Spectrogram, following the approved documentation, >but I still have problems. It appears that there are two adjustments >available for each filter position. I can set the width and the BFO >frequency. But I seem to be missing something when it comes to setting >the position of the dial frequency when I change modes. Should a clean, >centered CW signal remain centered in the bandpass when I switch from >CW to CW Rev.? I loose the signal completely and have to re-tune quite >a bit to find the signal again. Should it work this way, or do I have >something badly out of adjustment? > >To put it another way, can I adjust the filter width, BFO frequency, and >center frequency of each mode the way I want all at the same time? First, YES, you should be able to switch from CW Norm to CW Rev with little, if any, change in the centered signal, and (usually) no more than a 10-20 Hz frequency, if any at all... actually, it also depends upon how diligent you were in zero deating the other station. Second... what you are experiencing is usually the result of having BOTH BFOs (CW Norm _and_ Rev) set to the SAME SIDE of the filter passband. Check either the frequency of the BFO setting(s), OR you can also compare the 3-digit DAC steps. Both values can be obtained while you are IN CAL | FIL mode, and you can use either one with equal facility. Assuming you are performing the Spectrogram alignment on a back LOWER than 15M (I personally prefer 40M but anything between 160M and 17M should work), both the frequency and the DAC value should be BELOW the correseponding values for filter center if you are aligning CW NORMAL, and they should be ABOVE filter center if you are aligning CW REV. Check and let me know what you find. 73 - Tom Hammond N0SS +++++++++++++++ Reply-To: "Don Wilhelm" From: "Don Wilhelm" To: , "Peter Lutz AA6AV" Subject: Re: [Elecraft] Cal Fil possibilities in the K2 Date: Sun, 6 Jan 2002 09:27:30 -0500 Peter, Tom (N0SS) gave you a correct answer, so all I can do is to say part of it in another way. When you are set up with Spectogram, position both the CW and CW REV BFOs to center the passband around your the sidetone frequency that you have chosen. Note that CW and CW REV are similar to LSB and USB - in other words, the CW BFO will be on the lower side of the passband while the CW REV BFO will be on the upper side of the passband. You will not see it that way in the Spectogram display unless you look carefully - the passband should flip around the center frequency when you get it right (i.e. the audio frequencies below the filter center in CW mode will become the frequencies above the filter center in CW REV) If the filter shape were perfectly symetrical you would not be able to see it at all, but if you look closely at the slightly jagged edges on the filter slope, you can see the effect. 73, Don Don Wilhelm - Wake Forest, NC W3FPR home page: http://www.qsl.net/w3fpr/ QRP-L # 485 K2 SN 0020 mailto: w3fpr at arrl.net ----- Original Message ----- > To put it another way, can I adjust the filter width, BFO frequency, and > center frequency of each mode the way I want all at the same time? +++++++++++++++ From: "Dan Barker" To: "Elecraft" Date: Wed, 20 Feb 2002 08:26:54 -0500 Subject: [Elecraft] K2 CW CAL FIL method Group: What's wrong with this method (besides it doesn't confirm you are on the = correct sideband): Zero-beat to WWV. Launch Spectrogram and put a marker at your desired CW note. (the WWV = carrier should spike right under the mark). Go into CAL FIL and adjust the AF Gain to see the WWV spike above the = noise, hit DISPLAY and then tweak the spike back under the mark. Also = adjust passband widths if necessary. Exit Menu and find a quiet spot (or better yet, hook up the noise = source). Return to CAL FIL on FL 4 (Yes 4, we're doing this inside out). Hit DISPLAY or BFO and center the passband on the mark. Exit menu. Retune to WWV (or whatever steady carrier you are using) and zero beat = with FL4. Reenter CAL FIL and set the other 3 filters to match the audio note of = FL4. There is some interaction between FL1 and FL4, so an occational = check of zero beat is done. That's it. It seems a definitive way to minimize the note moving around. = You are simply matching FL1, FL2 and FL3's note to FL4's, which isn't = touched after step 6. Notes: 1) This is for the CW filters. I have NO IDEA how to do SSB filters = (My KSB2 is installed, but the filters aren't tuned yet). 2) This method came up because doing it frontwards, I seemed to always = have a useless 100 Hz setting. The passband of the tight filter was down = around 500 Hz, with the skirt down 10 dB at my desired note (trying for = 600 Hz). Tweaking FL4 only caused the note to jump around as you cycle = the filters, as many have noted. 3) Would something like this work for SSB? I don't even know how to = zero-beat an SSB signal. I guess you have to know what the OM or YL is = supposed to sound like, and then twist the knob until s/he sounds right? = Hummmm. Well, I know how to adjust FL4, and PSK31 uses FL4 (but I bet it = won't work without getting 1-3 right). There'll be late night lights in = the shack tonight! Dan Barker / WG4S / K2 #2456 +++++++++++++++++++ From: DolfinDon at aol.com Date: Wed, 20 Feb 2002 09:04:58 EST To: elecraft at mailman.qth.net Subject: [Elecraft] K2 CW CALFIL method In a message dated 2/20/2002 7:28:33 AM Central Standard Time, dbarker at visioncomm.net writes: Would something like this work for SSB? I don't even know how to zero-beat an SSB signal. I guess you have to know what the OM or YL is supposed to sound like, and then twist the knob until s/he sounds right? Hummmm. ================= Hi Your CW filter setting is similar to the method I use except I use the 7.000 MHz birdie after I center the filters with Spectrogram. Set a Spectrogram marker at your sidetone frequency. Center the bandpass for each filter on that marker for CWn and CWr. Now with the antenna disconnect find the internal birdie at around 7.000 MHz. Go out of menu to normal and adjust the VFO so the birdie on the Spectrogram display is on top of the marker. Now without touching the VFO go into cal filter and make a small adjustment to each filter so the birdie is on top of the marker for each filter in CWn and CWr. When all is set up properly you can zero beat a CW signal and switch between filters or CWn or CWr with no change in tone. For SSB you can use the audio tones on WWV at 10.000 MHz. The tones are 500 and 600 Hz on alternating minutes with a 1000 Hz tone on the minute. Check the WWV website for the format. Don Brown KD5NDB ++++++++++++++++++++ From: "Dan Barker" To: "Elecraft" Subject: FW: [Elecraft] K2 CW CAL FIL method Date: Wed, 20 Feb 2002 13:29:50 -0500 The important distinction here, is NOT TO ADJUST FL4. FL4 is so tight, adjustments shift the passband too far from the cw offset. Adjust the other 3 to match 4. That was my point. I'll try your suggestion on SSB Filters, after my eyes settle down. I've been to the eye doctor (clean bill o health, yea), but was dialated. The screen sure does quiver! I've got the WWV schedule format. Dan +++++++++++++++++++ Reply-To: "Don Wilhelm" From: "Don Wilhelm" To: "Dan Barker" , , Subject: Re: [Elecraft] K2 CW CALFIL method Date: Wed, 20 Feb 2002 21:11:21 -0500 ----- Original Message ----- > > Would something like this work for SSB? I don't even know how to zero-beat an > SSB signal. I guess you have to know what the OM or YL is supposed to sound > like, and then twist the knob until s/he sounds right? Hummmm. > Don, Dan and gang, Setting the SSB filters is a bit more complex than the CW filters - but it need not be any more difficult if you are using Spectogram or some other spectral display. The procedure goes like this: 1) Determine the filter bandpass you want to use - if you have the SSB option installed, use the OP1 filter. 2) Use a noise source (no signal) - a noise generator is best, but 'empty band' noise will do fine too. 3) Looking at the Spectogram display - set a marker at 300 Hz (set a second marker at 2300 Hz too if you desire - that one is not critical, but may help you observe the passband) 4) Start with LSB. By changing the BFO frequency - move the passband so that the 300 Hz marker is 3 to 6 dB down from the top of the passband (it will appear approximately 1/3 down on the Spectogram display - exactly how much depends on your noise source and the noise floor of your computer soundcard connection). That is all there is to it - you should now be able to easily tune SSB signals. You can go back and shift the 300 Hz response to better suit your ears if the recieved audio from a good SSB signal sounds too high or too low. Repeat for USB and any other variable filters that you would like to set for SSB. You will find additional information (with pictures - complements of Tom Hammond N0SS) on the Elecraft website - http://www.elecraft.com/Apps/new_fil_docs/k2_ssb_gram.pdf click this link or dig deep into the filter setting portion of the Builder's Resource page. 5) Now take a break and check the response in SSB transmit - this will require a second receiver to listen to your transmitted signal or another willing ham. Tape record the receiver output and listen critically. If your voice lacks sufficient lows, change the BFO to move the passband a bit lower - if it is too low (and hard to tune) move the passband higher. Using this method will customize OP1 and BFO1 to your individual voice - remember that BFO1 is always used for transmitting SSB. BTW - the same procedure works FB for setting the digital mode filters - just figure out what the audio tones are that are used for the data mode you want to set up for and make certain that all tones fit easily within the passband - set the BFO to make that condition occur. 73, Don Wilhelm - Wake Forest, NC W3FPR home page: http://www.qsl.net/w3fpr/ QRP-L # 485 K2 SN 0020 mailto: w3fpr at arrl.net ++++++++++++++++++ From: "Christian GONDARD" To: Subject: Re: [Elecraft] SSB cal fil problem Date: Tue, 15 Oct 2002 20:14:49 +0200 hello, I aggree with Jerry : I have noted the same behaviour : same BFO settings for FL1 es FL2 do not produce the same audio frequency on a reference transmitter. Attempts to correct that by adjusting BFO's do not work when you exit the MENU mode. But I have noted that "often !!" the modifications are correct after exiting MENU if you move through the different FL parameters after modifying one BFO. This is not a problem on SSB, nor CW. It becomes a problem when using digital modes (RTTY, and more on PSK), where TX and RX frequencies must be very closed (i.e : much less than 10 Hz for PSK). In my case, using same parameters for FL1 (OP1) for SSB and RTTY, gives a shift of 30 hertz between RX frequencies. After many tests, I was unable to find a better settings of BFO parameters, so I stay like that ... But I am curious to read an explanation about this behaviour .. best regards and 72/73 Chris / F6FTB / K2 #644 + KPA100 (waiting for the KAT100 !!) ----- Original Message ----- From: "Jerry Hancock" To: "George, W5YR" Cc: Sent: Tuesday, October 15, 2002 6:48 AM Subject: RE: [Elecraft] SSB cal fil problem > I don't have a problem with dial calibration as much as not understanding > the operation of FL1 and FL2. Setting the BFO to the same number for both > filters should give the same results, shouldn't it? > > -----Original Message----- > From: George, W5YR [mailto:w5yr at att.net] > Sent: Monday, October 14, 2002 9:44 PM > To: jehancoc at pacbell.net > Cc: elecraft at mailman.qth.net > Subject: Re: [Elecraft] SSB cal fil problem > > > I applied both the SSB filter mods. I am using OP1 for filter 1 and 2. I > > have both BFO settings at 209. I would assume that this would make both > FL1 > > and FL2 the same. When I zero beat WWV and watch the tones (as per an > > earlier post) I see the 500hz and 600hz tones at the correct place in the > > spectrum using sound forge spectrum analysis. When I switch to FL2 with > the > > BFO settings at 209, the tones shift up about 39hz in the FFT. > > > > If I go back to CAL FIL and adjust FL2 to say 207, the spectrum display > > changes and I can get FL2 to match FL1 (as to the position of the tones). > > If I then exit FL2 and loop back to FL1, FL1 is correct. Pressing XFIL > once > > to select FL2 and the BFO setting is at 207 but the tone is back where it > > was, 39hz off. Setting the BFO for FL2 to 205 corrects it until I loop > back > > around again. > > > > If I change FL1 to 211 I can make the tone move and leaving FL2 at 209, If > I > > loop through the filters, it is ok. > > > > This happens on LSB on 14mhz. The difference seems less on 40m. I can > > leave the USB filters at the same BFO settings without an audio shift. > > > > So what gives? > > > > Thanks, I enjoy this radio to no end. +++++++++++++++ Date: Tue, 15 Oct 2002 13:02:00 -0500 From: "George, W5YR" Organization: AT&T WorldNet Service To: Christian GONDARD Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] SSB cal fil problem One must change the filter selection after making any change in order to save the latest value. If this is not done, the new value will not replace the old one. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas In the 57th year and it just keeps getting better! Fairview, TX 30 mi NE of Dallas in Collin county EM13qe K2 #489 Icom IC-765 #2349 Icom IC-756 PRO #2121 Christian GONDARD wrote: > > hello, > > I aggree with Jerry : I have noted the same behaviour : same BFO settings > for FL1 es FL2 do not produce the same audio frequency on a reference > transmitter. > Attempts to correct that by adjusting BFO's do not work when you exit the > MENU mode. But I have noted that "often !!" the modifications are correct > after exiting MENU if you move through the different FL parameters after > modifying one BFO. -- snip -- ++++++++++++++++++ Date: Wed, 5 Mar 2003 13:11:40 -0600 (CST) From: Paul Jensen To: Subject: AW: [Elecraft] counter probe mod > > 'Leave the frequency counter test cable connected to the BFO test point > > (TP2). ...' > > > > So only the reflector told me to remove it. > > If you look at some of the more up to date handbooks for the adapters, > then you will find the recomendation NOT to leave it connected to TP2. > > It does cause problems with spurs, especially on the higher bands. I > know this from personal experience. > > This really *should* be changed in the manual or at least be added to the > errata. > Perhaps a warning sticker (see below) placed inside the K2 cover would be a good idea: (the procedure is taken from a previous post). -------------------------------------------------------------- The recommended procedure is: 1) Plug the probe into TP1 and put the cover on. 2) Run CAL PLL. 3) Remove the cover, move the probe to TP3, put the cover back on. 4) Run CAL FIL. 5) Remove the cover, remove the probe, put the cover back on. ---------------------------------------------------------------- Paul Jensen AD5IW, PP-ASEL ++++++++++++++++++++