Re: [Elecraft] [K2] Is TX frequency susceptible to RF on chassis?
On 10/15/07, David Woolley <[EMAIL PROTECTED]> wrote: ... > broadcast stations. (Does anyone know a relatively accurate broadcast > station, receivable in a noisy location in the UK, and near the high end > of the VFO range?) I there is or was the LDS station from School of Electronic and Electrical Engineering, Leeds University on 5.000 MHz that is accurate to around 1x10^(-12). Otherwise there is RWM from Russia is at 4.996, 9.996, 14.996 MHz. -Michael, VE3TIX ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
Hi David! For fine tune C22 you can use the simplest method with PC and specrpogram. There is the original UA6HJQ's method: -connect K2's AF-out to PC mic-input, and phones to PC phone out; -turn On K2 and PC, and wait for 50-60 minutes (for temperature stability); -check the connection "TP1=>Control Board"; -run the Spectrogram, and set for it: Scale -60db, FFT 8192, Band 640 - 1329Hz and set marker to 1000Hz; -set LSB-mode, and tune VFO at 10001,00kHz (WWV), if ANT is connected you have to hear WWV-signals in headphones, -if we see the WWV-signal peaked on 1000Hz (our marker on Spectrogram), it's the ideal point for C22. -if not, turn VFO for peaking the WWV-signal at 1000Hz-marker. -f.e. if we have 10001,20kHz we'll have to subtract 20 (in later steps), if we have 1,80 we'll have to add 20 (in later steps) - MENU => CAL => CAL FCTR (don't touch VFO-knob!) - we can see 14914,70 (for example) - now if we had 10001,20 we must to subtract: 14914,70-20=14914,50 (if we had 1,80 => 14914,70+20=14914,90) -now slowly turn C22 for 14914,50 readings (or 14914,90) -recall CAL PLL for TP1 on 40m band -recall CAL FIL for TP2 on each filter/mode. Now you can recheck your K2 on WWV at 10001,00 kHz, as a rule the error makes few Hz. Same pictures you can see if follow here (in russian): http://www.hamradio.cmw.ru/elecraft/calibrated.htm 73! Alex K2#5287 On Mon, 15 Oct 2007 15:44:31 +0300, Don Wilhelm <[EMAIL PROTECTED]> wrote: David, The same principles work fine for any known frequency, it is just that the subtraction of the BFO frequency from the VFO frequency is not as straightforward. An AM station broadcasting standard and constant tones (such as WWV) is easiest because one can observe the demodulated audio tones with Spectrogram assuring accurate tuning. If you have a good ear, you may be able to tune to a station broadcasting music to within 5 or 10 Hz. If you do use an AM broadcast station without standard tones as your standard, I would suggest that you tune it by ear in LSB or USB first, then switch to CW while observing the audio with Spectrogram - the carrier should appear 'straight and tall' at the frequency you have set in the K2 for the sidetone pitch - thus assuring accurate tuning of the station. Then go back to SSB mode to set C22 while doing the subtraction between the VFO and BFO frequencies. A note to help - any adjustment of C22 will move the VFO frequency reading about 5 times faster than the BFO reading, so do the adjustment with the counter probe plugged into TP1 and then check the result in TP2. A few trials should yield an accurate setting. 73, Don W3FPR David Woolley wrote: Don Wilhelm wrote: refer to the K2 Dial Calibration article on my website http://w3fpr.qrpradio.com for techniques to accurately set the 4 MHz reference oscillator and the following steps to achieve good dial calibration. Unfortunately, the sun doesn't seem to favour picking up WWV. The original calibration was against the MHz birdies on an FRG7, which was, I think, calibrated against WWV in the past. However I just tried on some 41m broadcast stations, and it looks like the calibration might be 30 to 40 Hz high on that band, which probably equates to 50 to 70 Hz, in the same sense, on 10m, so I may try a calibration against those broadcast stations. (Does anyone know a relatively accurate broadcast station, receivable in a noisy location in the UK, and near the high end of the VFO range?) ___ 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/elecraftHelp: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- Отправлено M2, революционной почтовой программой Opera: http://www.opera.com/mail/ ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
David, The same principles work fine for any known frequency, it is just that the subtraction of the BFO frequency from the VFO frequency is not as straightforward. An AM station broadcasting standard and constant tones (such as WWV) is easiest because one can observe the demodulated audio tones with Spectrogram assuring accurate tuning. If you have a good ear, you may be able to tune to a station broadcasting music to within 5 or 10 Hz. If you do use an AM broadcast station without standard tones as your standard, I would suggest that you tune it by ear in LSB or USB first, then switch to CW while observing the audio with Spectrogram - the carrier should appear 'straight and tall' at the frequency you have set in the K2 for the sidetone pitch - thus assuring accurate tuning of the station. Then go back to SSB mode to set C22 while doing the subtraction between the VFO and BFO frequencies. A note to help - any adjustment of C22 will move the VFO frequency reading about 5 times faster than the BFO reading, so do the adjustment with the counter probe plugged into TP1 and then check the result in TP2. A few trials should yield an accurate setting. 73, Don W3FPR David Woolley wrote: Don Wilhelm wrote: refer to the K2 Dial Calibration article on my website http://w3fpr.qrpradio.com for techniques to accurately set the 4 MHz reference oscillator and the following steps to achieve good dial calibration. Unfortunately, the sun doesn't seem to favour picking up WWV. The original calibration was against the MHz birdies on an FRG7, which was, I think, calibrated against WWV in the past. However I just tried on some 41m broadcast stations, and it looks like the calibration might be 30 to 40 Hz high on that band, which probably equates to 50 to 70 Hz, in the same sense, on 10m, so I may try a calibration against those broadcast stations. (Does anyone know a relatively accurate broadcast station, receivable in a noisy location in the UK, and near the high end of the VFO range?) ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
David. Your situation as described in another email seems very similar to mine. I am operating a K2/10 with an indoor antenna, a closed loop approximately 20m in circumference with the feedpoint about 2m directly above the K2. The loop is fed via the KAT2, some 2.5m of RG-213 and an Elecraft BL-1 balun at the feed point. I have no RF ground, being in an upstairs bedroom. When connected to the power supply, the K2 is grounded through the electrical supply earth, but I have never noticed any difference when operating it from its internal battery, completely isolated. In over 6 years of operating, including frequency-sensitive digimodes, I have never noticed any frequency shift of the K2 TX frequency. I just attempted, by holding the FT-817 with whip antenna right next to my K2, to test for sensitivity to UHF, while monitoring a PSK31 station on 20m, and there was no perceptible change in frequency. Therefore I wonder if you should look elsewhere for the cause of the problem. Before investigating inside the K2, is your power supply immune to RF? Does the voltage change in the presence of RF? -- Julian, G4ILO K2 s/n: 392 K3 s/n: ??? G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf On 10/14/07, David Woolley <[EMAIL PROTECTED]> wrote: > I checked the transmit frequency relative to the receive one with a > dummy load, at 10 watts, and there is no problem. It's possible that > this is simply a combination of my voice and the filter settings, but it > could also be that RF on the chassis is upsetting the BFO and/or > reference oscillator control voltages. Is this a known issue? ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
Don Wilhelm wrote: > the same sense, on 10m, so I may try a calibration against those Oops, I meant 20m. The same applies if I mentioned 10m in the original. -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
Don Wilhelm wrote: I do not believe that RF on the chassis could easily cause a frequency I hope that's the case, although UHF RF can cause a small shift, and I assume the MHz birdies are less affected than the varactor controlled oscillators. I suggest that you first take a good look at your SSB FL1 filter for both LSB and USB. If you have the curently normal SSB filter width of I'll have another look at that. tracking. If you have an extremely 'bassy' voice, then you may want to Low on USB would suggest the opposite. If you are using the K2 frequency indication to 'net' on a given frequency, your dial calibration may be off a bit. To get it right, As the frequency appeared to be round, I may have been influenced by that as well as the correct sound. refer to the K2 Dial Calibration article on my website http://w3fpr.qrpradio.com for techniques to accurately set the 4 MHz reference oscillator and the following steps to achieve good dial calibration. Unfortunately, the sun doesn't seem to favour picking up WWV. The original calibration was against the MHz birdies on an FRG7, which was, I think, calibrated against WWV in the past. However I just tried on some 41m broadcast stations, and it looks like the calibration might be 30 to 40 Hz high on that band, which probably equates to 50 to 70 Hz, in the same sense, on 10m, so I may try a calibration against those broadcast stations. (Does anyone know a relatively accurate broadcast station, receivable in a noisy location in the UK, and near the high end of the VFO range?) -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
David, I do not believe that RF on the chassis could easily cause a frequency shift, but then who knows because each situation like that is different. I suggest that you first take a good look at your SSB FL1 filter for both LSB and USB. If you have the curently normal SSB filter width of 2.4 kHz I recommend that you set up Spectrogram with markers at 300 and 2600 Hz, then adjust the BFO to center the passband between those markers. If you have the older 2.1 kHz filter use 300 and 2300 kHz markers. With the 2.4 kHz filter aligned that way, you should be able to use it for both transmit and receive with good fidelity and frequency tracking. If you have an extremely 'bassy' voice, then you may want to set FL2 up as I have described and set FL1 for a passband about 50 Hz lower (250 to 2550 Hz) and use FL2 for receive. If you are using the K2 frequency indication to 'net' on a given frequency, your dial calibration may be off a bit. To get it right, refer to the K2 Dial Calibration article on my website http://w3fpr.qrpradio.com for techniques to accurately set the 4 MHz reference oscillator and the following steps to achieve good dial calibration. Once you have assured yourself that the SSB filters are correct, try it again and see if there appears to be any difference. 73, Don W3FPR David Woolley wrote: This may be correlated with the balun thread. From the same station, I got a report that I was off frequency on 15m SSB and a more quantitative one, of 120Hz low, for 10m. This was during a local contest, so I couldn't do a lot of investigation on air, and I may not get many SSB opportunities on these bands in the near future. I checked the transmit frequency relative to the receive one with a dummy load, at 10 watts, and there is no problem. It's possible that this is simply a combination of my voice and the filter settings, but it could also be that RF on the chassis is upsetting the BFO and/or reference oscillator control voltages. Is this a known issue? The method I used to check with the dummy load isn't easily adapted to a live antenna, but as I've observed that the K2 has EMC problems with UHF transmitters, I tried holding a PMR446 transmitter close to various chassis seams and managed to upset the frequency by a small amount (beat frequency when SPOTted onto the 14MHz birdie), maybe no more than about 10Hz. This happened well after the point where the RF pickup was upsetting the received audio. On 15m I was using the balun, but the actual antenna is approximately resonant (disconnecting either side gives a strong drop in received noise). On 10m the antenna would be more like anti-resonant, so I would expect much more signal on the chassis. Unfortunately I didn't have a quantative report for 15m. If the frequency is shifting due to RF on the chassis, my next priority really is going to have to be sorting out a good internal antenna solution. External antennas are out of the question for various reasons, that includes flag poles - I don't have exclusive access to anything at ground level! ___ 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] [K2] Is TX frequency susceptible to RF on chassis?
This may be correlated with the balun thread. From the same station, I got a report that I was off frequency on 15m SSB and a more quantitative one, of 120Hz low, for 10m. This was during a local contest, so I couldn't do a lot of investigation on air, and I may not get many SSB opportunities on these bands in the near future. I checked the transmit frequency relative to the receive one with a dummy load, at 10 watts, and there is no problem. It's possible that this is simply a combination of my voice and the filter settings, but it could also be that RF on the chassis is upsetting the BFO and/or reference oscillator control voltages. Is this a known issue? The method I used to check with the dummy load isn't easily adapted to a live antenna, but as I've observed that the K2 has EMC problems with UHF transmitters, I tried holding a PMR446 transmitter close to various chassis seams and managed to upset the frequency by a small amount (beat frequency when SPOTted onto the 14MHz birdie), maybe no more than about 10Hz. This happened well after the point where the RF pickup was upsetting the received audio. On 15m I was using the balun, but the actual antenna is approximately resonant (disconnecting either side gives a strong drop in received noise). On 10m the antenna would be more like anti-resonant, so I would expect much more signal on the chassis. Unfortunately I didn't have a quantative report for 15m. If the frequency is shifting due to RF on the chassis, my next priority really is going to have to be sorting out a good internal antenna solution. External antennas are out of the question for various reasons, that includes flag poles - I don't have exclusive access to anything at ground level! -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. ___ 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
