Re: [Elecraft] [K3] Tunijng the Radio
Dave, To add to the replies which you have received, the width of your USB signal should also include those intermodulation products which appear at frequencies less than that of the suppressed carrier frequency, i.e. in the LSB region. If you tuned your K3 to 14.225 MHz, these IMD products would fall outside of your General Class portion of the band and could create interference. To be safe I would suggest that you do not operate your K3 in USB mode below 14.228 kHz. In Europe the top end of our 80m allocation is 3.800 MHz, and some European hams operate LSB on or very close to 3.800 MHz. This practice has caused some non-amateur users operating just above 3.800 MHz to complain about interference from amateur IMD products. Fortunately those complaints which I have heard are still at the muttering stage. 73, Geoff LX2AO On July 14, 2012 at 10:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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
Re: [Elecraft] [K3] Tunijng the Radio
http://www.contesting.com/articles/148 Chuck, KE9UW aka Jack, BMW Motorcycles BMWMOA #224 From: elecraft-boun...@mailman.qth.net [elecraft-boun...@mailman.qth.net] on behalf of David Guernsey [mooo1...@yahoo.com] Sent: Saturday, July 14, 2012 3:39 PM To: Elecraft List Subject: [Elecraft] [K3] Tunijng the Radio If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? 73 de Dave KJ6CBS __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Being a SDR there is really no suppressed carrier as the carrier is never created only the sideband for the mode selected. So unless you have signficant splatter there should not be an IMD problem with a K3. Again assuming no splatter and a properly functioning radio. This is no analog radio and all TX is based on the DSP first and then the TX filter last. ~73 Don KD8NNU On Sun, Jul 15, 2012 at 7:34 AM, Geoffrey Mackenzie-Kennedy wrote: Dave, To add to the replies which you have received, the width of your USB signal should also include those intermodulation products which appear at frequencies less than that of the suppressed carrier frequency, i.e. in the LSB region. If you tuned your K3 to 14.225 MHz, these IMD products would fall outside of your General Class portion of the band and could create interference. To be safe I would suggest that you do not operate your K3 in USB mode below 14.228 kHz. In Europe the top end of our 80m allocation is 3.800 MHz, and some European hams operate LSB on or very close to 3.800 MHz. This practice has caused some non-amateur users operating just above 3.800 MHz to complain about interference from amateur IMD products. Fortunately those complaints which I have heard are still at the muttering stage. 73, Geoff LX2AO On July 14, 2012 at 10:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Don: Not so at all - whilst the low level SSB generated by the K3's DSP may be close to theoretically perfect, intermodulation products produced by the K3's IPA and final amplifier stages are present in quantity and are the limiting factor. Jack K8ZOA On 7/15/2012 8:02 AM, gold...@charter.net wrote: Being a SDR there is really no suppressed carrier as the carrier is never created only the sideband for the mode selected. So unless you have signficant splatter there should not be an IMD problem with a K3. Again assuming no splatter and a properly functioning radio. This is no analog radio and all TX is based on the DSP first and then the TX filter last. ~73 Don KD8NNU On Sun, Jul 15, 2012 at 7:34 AM, Geoffrey Mackenzie-Kennedy wrote: Dave, To add to the replies which you have received, the width of your USB signal should also include those intermodulation products which appear at frequencies less than that of the suppressed carrier frequency, i.e. in the LSB region. If you tuned your K3 to 14.225 MHz, these IMD products would fall outside of your General Class portion of the band and could create interference. To be safe I would suggest that you do not operate your K3 in USB mode below 14.228 kHz. In Europe the top end of our 80m allocation is 3.800 MHz, and some European hams operate LSB on or very close to 3.800 MHz. This practice has caused some non-amateur users operating just above 3.800 MHz to complain about interference from amateur IMD products. Fortunately those complaints which I have heard are still at the muttering stage. 73, Geoff LX2AO On July 14, 2012 at 10:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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 __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Hi Jack, So I think what you are telling me is that the IPA is after the DSP and that obvioulsy any inperfections in this circuit and the final amp are what creates the IMD products. Is that another reason that the tx filter is 2.7 or 2.8 wide at the skirts to act as a wall to prevent this from getting out on the air compared to using a 3.0 wide filter. Thanks Don ~73 Don KD8NNU On Sun, Jul 15, 2012 at 8:51 AM, Jack Smith wrote: Don: Not so at all - whilst the low level SSB generated by the K3's DSP may be close to theoretically perfect, intermodulation products produced by the K3's IPA and final amplifier stages are present in quantity and are the limiting factor. Jack K8ZOA On 7/15/2012 8:02 AM, gold...@charter.net wrote: Being a SDR there is really no suppressed carrier as the carrier is never created only the sideband for the mode selected. So unless you have signficant splatter there should not be an IMD problem with a K3. Again assuming no splatter and a properly functioning radio. This is no analog radio and all TX is based on the DSP first and then the TX filter last. ~73 Don KD8NNU On Sun, Jul 15, 2012 at 7:34 AM, Geoffrey Mackenzie-Kennedy wrote: Dave, To add to the replies which you have received, the width of your USB signal should also include those intermodulation products which appear at frequencies less than that of the suppressed carrier frequency, i.e. in the LSB region. If you tuned your K3 to 14.225 MHz, these IMD products would fall outside of your General Class portion of the band and could create interference. To be safe I would suggest that you do not operate your K3 in USB mode below 14.228 kHz. In Europe the top end of our 80m allocation is 3.800 MHz, and some European hams operate LSB on or very close to 3.800 MHz. This practice has caused some non-amateur users operating just above 3.800 MHz to complain about interference from amateur IMD products. Fortunately those complaints which I have heard are still at the muttering stage. 73, Geoff LX2AO On July 14, 2012 at 10:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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 __ 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 __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Sorry Don, I was offline and I have just seen your comment, to which I see Jack has responded. Thank you Jack!! 73, Geoff LX2AO On July 15, 2012 at 2:02 PM, Don KD8NNU wrote: Being a SDR there is really no suppressed carrier as the carrier is never created only the sideband for the mode selected. So unless you have signficant splatter there should not be an IMD problem with a K3. Again assuming no splatter and a properly functioning radio. This is no analog radio and all TX is based on the DSP first and then the TX filter last. ~73 Don KD8NNU __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Don: The TX crystal filter is ahead of the IPA and HPA stages and while a narrower filter may help a bit, the real source of almost all transmitted 3rd, 5th, 7th, 9th etc. order IMD products is the power stages. Jack K8ZOA On 7/15/2012 9:12 AM, gold...@charter.net wrote: Hi Jack, So I think what you are telling me is that the IPA is after the DSP and that obvioulsy any inperfections in this circuit and the final amp are what creates the IMD products. Is that another reason that the tx filter is 2.7 or 2.8 wide at the skirts to act as a wall to prevent this from getting out on the air compared to using a 3.0 wide filter. Thanks Don ~73 Don KD8NNU On Sun, Jul 15, 2012 at 8:51 AM, Jack Smith wrote: Don: Not so at all - whilst the low level SSB generated by the K3's DSP may be close to theoretically perfect, intermodulation products produced by the K3's IPA and final amplifier stages are present in quantity and are the limiting factor. Jack K8ZOA On 7/15/2012 8:02 AM, gold...@charter.net wrote: Being a SDR there is really no suppressed carrier as the carrier is never created only the sideband for the mode selected. So unless you have signficant splatter there should not be an IMD problem with a K3. Again assuming no splatter and a properly functioning radio. This is no analog radio and all TX is based on the DSP first and then the TX filter last. ~73 Don KD8NNU On Sun, Jul 15, 2012 at 7:34 AM, Geoffrey Mackenzie-Kennedy wrote: Dave, To add to the replies which you have received, the width of your USB signal should also include those intermodulation products which appear at frequencies less than that of the suppressed carrier frequency, i.e. in the LSB region. If you tuned your K3 to 14.225 MHz, these IMD products would fall outside of your General Class portion of the band and could create interference. To be safe I would suggest that you do not operate your K3 in USB mode below 14.228 kHz. In Europe the top end of our 80m allocation is 3.800 MHz, and some European hams operate LSB on or very close to 3.800 MHz. This practice has caused some non-amateur users operating just above 3.800 MHz to complain about interference from amateur IMD products. Fortunately those complaints which I have heard are still at the muttering stage. 73, Geoff LX2AO On July 14, 2012 at 10:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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 __ 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 __ 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 __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Few filters have vertical skirts. They roll off gradually; the slope of that rolloff is one of the measures of filter quality. The filter width is often (but not always) described as the 6 dB down point on that rolloff curve, A filter described as 2.8 kHz wide will pass some energy through at frequencies outside its 2.8 kHz bandwidth. Graphs of representative Elecraft K3 filters are available at http://www.elecraft.com/K3/K3_filter_plots.htm For example, the representative 2.8 kHz 8-pole filter is 2.888 kHz at 6 dB down, and 4.488 kHz at 60 dB down. The 2.7 kHz 5-pole filter is wider at the 60 dB down point. Some older radios depended on filtering to remove the unwanted sideband and carrier. Current generation radios generate just the desired SSB signal, without the unwanted sideband and without the carrier. There are a number of amplifiers after the SSB signal generation and filtering that generate various levels of IMD products. It's up to the radio manufacturer to provide equipment that meets the FCC specified limits when the equipment is operated according to its owner-level instructions. It's up to us to operate the radio within these described limits in order to keep the unwanted signals within the FCC-prescribed limits and good amateur practice. When the instruction manual says 4-5 bars, that doesn't mean turn it up as far as it will go. http://www.youtube.com/watch?v=XuzpsO4ErOQ None of this is specific to the K3 except the details of the filters. 73 de Dick, K6KR -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of gold...@charter.net Sent: Sunday, July 15, 2012 6:13 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] Tunijng the Radio Hi Jack, So I think what you are telling me is that the IPA is after the DSP and that obvioulsy any inperfections in this circuit and the final amp are what creates the IMD products. Is that another reason that the tx filter is 2.7 or 2.8 wide at the skirts to act as a wall to prevent this from getting out on the air compared to using a 3.0 wide filter. Thanks Don ~73 Don KD8NNU On Sun, Jul 15, 2012 at 8:51 AM, Jack Smith wrote: Don: Not so at all - whilst the low level SSB generated by the K3's DSP may be close to theoretically perfect, intermodulation products produced by the K3's IPA and final amplifier stages are present in quantity and are the limiting factor. Jack K8ZOA On 7/15/2012 8:02 AM, gold...@charter.net wrote: Being a SDR there is really no suppressed carrier as the carrier is never created only the sideband for the mode selected. So unless you have signficant splatter there should not be an IMD problem with a K3. Again assuming no splatter and a properly functioning radio. This is no analog radio and all TX is based on the DSP first and then the TX filter last. ~73 Don KD8NNU On Sun, Jul 15, 2012 at 7:34 AM, Geoffrey Mackenzie-Kennedy wrote: Dave, To add to the replies which you have received, the width of your USB signal should also include those intermodulation products which appear at frequencies less than that of the suppressed carrier frequency, i.e. in the LSB region. If you tuned your K3 to 14.225 MHz, these IMD products would fall outside of your General Class portion of the band and could create interference. To be safe I would suggest that you do not operate your K3 in USB mode below 14.228 kHz. In Europe the top end of our 80m allocation is 3.800 MHz, and some European hams operate LSB on or very close to 3.800 MHz. This practice has caused some non-amateur users operating just above 3.800 MHz to complain about interference from amateur IMD products. Fortunately those complaints which I have heard are still at the muttering stage. 73, Geoff LX2AO On July 14, 2012 at 10:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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
Re: [Elecraft] [K3] Tunijng the Radio
You'll be in the General portion of 20m. Your band spread will take you up to 14.2278 (+2.8 khz) which will be fine on USB. 73, Ian, KM4IK On Jul 14, 2012 6:55 PM, David Guernsey mooo1...@yahoo.com wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? 73 de Dave KJ6CBS __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
In general, you have to allow for the width of your signal. As a rule of thumb, I figure my USB/LSB signals occupy the range from the VFO suppressed carrier frequency to 3 kHz away from the VFO frequency. Maybe 4 if you have ESSB selected. If you tune to 14.225, the suppressed carrier frequency is 14.225, and your USB signal will occupy the range roughly from 14.225 to 14.228, so you're within the General section of the band. The problem we all run into is the high end of these bands. If you set your VFO (the suppressed carrier frequency) above 14.347, parts of your USB signal will spill off the end of the band, 14.350. On 40 meters, LSB, the situation is reversed. If you tune your VFO to a suppressed carrier frequency of 7.300 and the LSB signal will fall into the range from 7.297 to 7.300. However you can't crowd the bottom edge of the 40 meter band. For a general, your lowest frequency is 7.175. You shouldn't tune below 7.178 to avoid putting any part of your LSB signal below 7.175. 73 de Dick, K6KR -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of David Guernsey Sent: Saturday, July 14, 2012 1:40 PM To: Elecraft List Subject: [Elecraft] [K3] Tunijng the Radio If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? 73 de Dave KJ6CBS __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Well, you'd be legal if your dial is accurate, but I prefer to move up a bit to allow for Professor Murphy. And don't forget to stop at least 3kHz below the top (14.347000). Reverse is true for LSB. ...bill nr4c Sent from my Verizon Wireless Droid -Original message- From: David Guernsey mooo1...@yahoo.com To: Elecraft List elecraft@mailman.qth.net Sent: Sat, Jul 14, 2012 20:39:33 GMT+00:00 Subject: [Elecraft] [K3] Tunijng the Radio If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? 73 de Dave KJ6CBS __ 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 __ 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
Re: [Elecraft] [K3] Tunijng the Radio
Dave, You have already received some correct answers, but let me try to inject a bit of generalized information that should allow you to figure this out in the future for any band and for either LSB or USB. The K3 will display the (suppressed) carrier frequency. That means that USB signals will be higher in frequency than the carrier, so in the specific case of your question, you will be in the band (assuming the K3 frequency is properly calibrated). Similarly, LSB signals will be below the carrier frequency, so if you are operating on 80 meters where your lower band limit is 3800 kHz, you will be within the general portion of the band if your VFO is set to 3804 kHz (to be safe). If you are absolutely certain your SSB width is 3 kHz or less, then you can go as low as 3803 kHz. 73, Don W3FPR On 7/14/2012 4:39 PM, David Guernsey wrote: If I tune my K3 to 14.225 MHz will I be in the General Class portion of the 20 meter band, or do I have to allow for the width of my USB signal when I transmit? __ 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
