Re: [Elecraft] K2 Filter settings
Thanks Don Since sending that email, I'd come across Wayne's article on the mechanics of CAL FIL. That opened my eyes to something I'd read, but clearly not absorbed: i.e. when a modified BFO is saved, the K2 re-calculates the value of VCO needed to obtain the same AF tone as before. Although the audio moves moves when the BFO is adjusted, once the BFO is saved, the tone goes back to where it was (or within 20Hz anyway). One thing though. Unless it's just my KSB2 filter, you can still see WWV's 100Hz sub-carrier on DM780 when the filter skirts are set as you suggest. It's very low, but DM780 has a high dynamic range and the carrier is just visible. Gareth, M5KVK Sent from my iPad On 3 Mar 2015, at 02:11, Don Wilhelm w3...@embarqmail.com wrote: Gareth, That is NOT correct. You must do things in order and all will work out properly. First, the 100 Hz WWV subcarrier should be outside the passband of the SSB filters, so it will have a very low amplitude. It is better to use the alternating 500 and 600 Hz as well as the 'on the minute' tone at 1000Hz to determine the correct tuning of WWV. The tone at 2 minutes after the hour is 440Hz. If your SSB OP1 (or FL1 if no KSB2) filter passbands are not properly aligned, do an initial alignment of the LSB and USB filters so the filter passband low frequency slope -5dB point is at 300 Hz (use Spectrogram to observe the passband position). Once the SSB FL1 filter is adjusted, then receive WWV and use the Spectrogram (or other audio spectrum analyzer) to properly tune the WWV transmitted tones. Once tuned properly, lock the VFO to prevent moving the VFO knob. With WWV properly tuned, set to CAL FCTR and alternate the internal counter probe between TP2 and TP1 while adjusting Control Board C22. Since all WWV transmissions are on '000.000 kHz boundaries, all you need to do is observe the 4 low order digits in the CAL FCTR display and you do not have to do the subtraction in every case. Once C22 is properly adjusted, put the counter probe in TP1 and run CAL PLL. When CAL PLL finishes, then go to CAL FIL. Even though the FL1 passband has been previously set, you must still change the BFO settings. Move them up one DAC count and back down to where they were before. Then adjust the BFOs for SSB FL2 thru FL4. I set the low frequency slope of FL2 at 350Hz, FL3 at 400Hz, and FL4 at 500Hz. Adjust the BFOs for the CW filters (and RTTY filters if you have them enabled) to properly position the filter passbands. If they were set correctly before, move them by one DAC step and back again - this is to force the BFO frequencies to be recorded into EEPROM with the current 4MHz reference frequency. After those steps, re-check the WWV tuning. It should be correct within 20 Hz. The BFO DAC steps are approximately 20 Hz wide, so you may see a shift in the tuning by that amount. If it is greater than 20 Hz, re-do the entire procedure from the beginning. I do this procedure more than 3 times a week on K2 repairs, and it always works. 73, Don W3FPR On 3/2/2015 11:11 AM, Gareth - M5KVK wrote: I realise this is close to becoming an obsession, but I really want to understand what's going on. Once I'd gone through my modified version of Wayne's process for adjusting the VCO (i.e. adjusting the VFO to have the WWV 100Hz sub-carrier on 100Hz), I realised that this applied only to LSB FIL1. As soon as I switched to FIL2, the sub-carrier moved and I needed to use CAL FIL to adjust it back. Also, if you want to move the position of the filter in the audio spectrum (e.g. to change where the skirts are), and thus change the BFO; you need to run Wayne's process again. Is that right? 73, Gareth - M5KVK __ 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 Message delivered to w3...@embarqmail.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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] Using CAL FIL and Spectrogram to set up the K2 filters
Good points, Don. Last night, I experimented using DM780 (the datamodes program in the HRD suite) to visualise the audio rather than using Spectogram. I found that the waterfall made it much easier to see the shape of the filters. I don't have a noise generator so I'm using band noise. The randomness makes it quite difficult to see the shape in Spectogram; particularly at low audio; whereas a waterfall is more defined. I'll return to the setting up of the filters at the weekend and report back. Incidentally, using the waterfall exposed that I hadn't actually set the VCO calibration as I originally thought. As I said earlier, I actually tuned off WWV by 600Hz. Now I'm using a waterfall I can see that I was actually tuning the 100Hz timecode subcarrier. Gareth, M5KVK Sent from my iPad On 26 Feb 2015, at 14:01, Don Wilhelm w3...@embarqmail.com wrote: Gareth, Good work. May I offer a couple suggestions: 1) On SSB filters other than the FL1 OP1 filter, look carefully at the actual filter width. On many K2s, the actual width is far wider than that indicated by the K2 display. You ideally want to have each filter progression about 200 to 300 Hz more narrow then the prior filter. The easiest way to set that up is to first do LSB - the low frequency slope of the passband will not move substantially as you adjust the width. The set the BFOs for the filters after adjusting00 the width. 2) Rather than using SSB FL4 for PSK and other data modes, turn on RTTY in the secondary menu. That gives you another set of filters and an independent compression setting from SSB and you don't have to remember to turn compression off when using data modes. I normally set RTTY FL1 the same as SSB FL1 (including the BFO settings - RTTY is LSB and RTTY rev is USB) and then set the FL2 to 1000 Hz, FL3 to 700 Hz and FL4 to 400 Hz widths. I center those 3 filters on 1000 Hz. If you are not able to properly center the 400 Hz wide filter, you will have to pad the BFO with a small value capacitor (try 15 to 22pF) between pins 6 and 3 of RF board U11 - then recheck the BFO range. If you do have to make that change, you will need to re-do all the BFO alignments. 73, Don W3FPR On 2/26/2015 8:29 AM, Gareth - M5KVK wrote: Having finally got my KSB2 board working (it was a hi-resistance solder joint: enough to depress performance but not stop all signals), and calibrated the dial, I turned to setting up the filters. I started with the filter widths and BFO settings in the KSB2 manual, but it didn't sound right. So I decided to use WWV and Spectrogram. Now that I knew that the VFO was OK, I set it to 1.00. No audio on LSB or USB, which is good. I then tuned off by 600Hz to create a steady signal at 1.60kHz (.40kHz on the other sideband) and displayed the audio on spectrogram with a 600Hz marker set. I then went through CAL FIL, adjusting the BFO so that the audio tone was exactly 600Hz. I did this on all modes and filter widths: except FL4 on LSB and USB, which I adjusted for a 1000Hz centre (so I can use them for PSK31). I was surprised how far off the displayed spectrum was with the factory settings. On USB FL4, the centre was at 400Hz with the manual’s suggested BFO setting. 73, Gareth M5KVK __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] Confused when calibrating 4MHz oscillator
Right. It was the relationship between BFO and VFO I was missing. Nevertheless, I followed the procedure last night and it seems to have worked. I admit that it took three goes until I got the knack of adjusting C22 correctly, but it worked. I knew it would but I like to understand how rather than just taking it on trust. Thanks (again), Don. Sent from my iPad __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K2] Looking for a UK based expert to debug KSB2
Thanks, Frank, however if you read the email traffic on here relating to this you'll see that we're a bit beyond any jumper problems. I wish it were that simple. 73, Gareth Sent from my iPad On 24 Jan 2015, at 23:09, Frank Krozel kg9hfr...@gmail.com wrote: If I recall there are two jumpers that you needed to add. Frank KG9H On Jan 24, 2015, at 11:57 AM, Gareth - M5KVK m5...@m5kvk.org wrote: OK, I have to admit defeat. I can't see what's wrong with the KSB2 board I built for my K2. I need somebody with more skill than I to take a look. I'd prefer somebody in the UK, simply because of shipping costs. If there is somebody who would be willing to put my board in their own K2 and work out what the problem is, please email me direct at M5KVK at M5KVK dot ORG. I'll send them the board to take a look and,hopefully, get it working. I'll pay reasonable costs of course. 73 Gareth, M5KVK __ 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 Message delivered to kg9hfr...@gmail.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 Message delivered to arch...@mail-archive.com
