Re: [Elecraft] KX-1 BC interference on 20m
Hello Don I certainly wouldn't want to give the impression that I'm not really pleased with the KX-1 because it's given me a huge amount of pleasure in a relatively short length of time. I think I may have hit upon something- the KX-1 received a knock when camping and I have now discovered that the knock broke both solder joints for the ground connection on the bnc socket. Looking at them they seemed dry anyway and now they have been resoldered the problem has all but disappeared. I'm not looking for a perfect transceiver of course, but the BC stations were fairly intrusive and if I've got that sorted now then I shall be happy. Thanks to all for the advice received! 73 Stephen G4SJP On 26/08/2008 00:51, Don Wilhelm [EMAIL PROTECTED] wrote: Stephen and Ed, I was thinking along those same lines. On 20 meters, the KX1 LO signal is below the RF signal, so a strong BC station in the 4.1 to 4.3 MHz range could push itself through and be heard on the upper end of the 20 meter band. If you have no stations on that part of the spectrum, you can likely reject the assumption of an image response. The KX1 design faced many challenges in order to stuff all that performance in a small space, so the design is a bit of a compromise. The front end suffers from responses in the presence of strong RF energy just like any other Gilbert cell mixer connected in the receiver front end (with no RF amp stage for isolation). My understanding is that the Gilbert cell mixer can generate 'funny stuff' in the presence of strong RF energy fields like might be found in Europe - in reading EMRFD, I find that Wes Hayward does not even recommend the gilbert cell mixer for use in receivers that will be used on the Eastern side of the US for this very reason. In addition, the DDS does have some spurs that can be mysterious - if the offending signal tunes more quickly than normal signals, you are likely hearing the result of one of the DDS spurs. The KX1 is a good design, but it just is not perfect in all ways. You may be hearing the result of one of these imperfections - OTOH, you *could* have a problem there. Comparison with another KX1 under the same circumstances is one way of telling whether a problem exists or it is just one of those design compromise situations. 73, Don W3FPR Ed - K9EW wrote: Hi Stephen, It might help if you could identify the SW stations you're hearing, and find out what frequency they're on. What you could be hearing is a very strong signal on the receiver's image frequency, and the only thing you could do would be to add more selectivity to the front end to attenuate the signal on the image frequency. Ask Elecraft, they would know. 73, ed - k9ew www.k9ew.us\ ___ 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 No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.6.7/1631 - Release Date: 8/24/2008 12:15 PM ___ 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] KX-1 BC interference on 20m
Stephen, Yes, a poorly connected BNC shell could act as a mixer itself and cause all sorts of wierd happenings - especially within a strong RF field as exists in Europe with those BIG broadcast stations. 73, Don W3FPR Stephen Prior wrote: Hello Don I certainly wouldn't want to give the impression that I'm not really pleased with the KX-1 because it's given me a huge amount of pleasure in a relatively short length of time. I think I may have hit upon something- the KX-1 received a knock when camping and I have now discovered that the knock broke both solder joints for the ground connection on the bnc socket. Looking at them they seemed dry anyway and now they have been resoldered the problem has all but disappeared. I'm not looking for a perfect transceiver of course, but the BC stations were fairly intrusive and if I've got that sorted now then I shall be happy. Thanks to all for the advice received! 73 Stephen G4SJP ___ 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] KX-1 BC interference on 20m
As I have mentioned before, I really enjoyed using the KX-1 on holiday in Europe this year but found that there were several broadcast stations appearing across 20m from about 14.20MHz upwards. I was using a roughly 5/8 wave vertical antenna with counterpoise and the internal ATU. Is this normal operation, or should I delve into the manual for alignment procedures? I am at a disadvantage in that I did not build the unit. The radio suffered a pretty bad knock whilst camping and I am wondering if something is adrift. Thanks and 73 Stephen G4SJP ___ 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] KX-1 BC interference on 20m
Stephen - Some of those SW BC stations are pretty strong - as in hundreds of KW. It is possible that what you were hearing is the 2nd harmonic from these stations operating in the 41-meter (7.10 - 7.35 MHz) Shortwave Broadcast (SW BC) band. Given a 100 KW transmitter, with 2nd harmonics 40 dB down from the fundamental (which would be considered reasonably good suppression) is still 10 watts at the 2nd harmonic, or roughly 5 times the output power of a 2-watt KX1. Since the European (ITU Region 1) 40-meter SW BC band starts at 7100 KHz, I think, then it would be normal to hear such signals starting at 14.200 and continuing up in frequency across the rest of the 20 meter band. 100 KW is probably more or less a median power level for SW BC stations, with some running less, and some quite a bit more - as in 500 KW. And, this is real power from the PA. Add to this the fact that some stations get another 10 dB or more from antenna gain in whatever direction they happen to be beaming and we're talking big time competition with amateur signals. Another consideration is that SW BC stations are usually designed to be frequency agile, and so they often have antennas that can be used on multiple frequencies. Such antennas can be efficient radiators of harmonic energy. So, the best hope is to wait for a few more years until the 40 meter broadcasters move above 7300 KHz, which I think is in the works, but I have forgotten just when it is supposed to happen. In any case, the problem you describe will be with us for a few more years. - Jim, KL7CC Stephen Prior wrote: As I have mentioned before, I really enjoyed using the KX-1 on holiday in Europe this year but found that there were several broadcast stations appearing across 20m from about 14.20MHz upwards. I was using a roughly 5/8 wave vertical antenna with counterpoise and the internal ATU. Is this normal operation, or should I delve into the manual for alignment procedures? I am at a disadvantage in that I did not build the unit. The radio suffered a pretty bad knock whilst camping and I am wondering if something is adrift. Thanks and 73 Stephen G4SJP Stephen Prior wrote: As I have mentioned before, I really enjoyed using the KX-1 on holiday in Europe this year but found that there were several broadcast stations appearing across 20m from about 14.20MHz upwards. I was using a roughly 5/8 wave vertical antenna with counterpoise and the internal ATU. Is this normal operation, or should I delve into the manual for alignment procedures? I am at a disadvantage in that I did not build the unit. The radio suffered a pretty bad knock whilst camping and I am wondering if something is adrift. Thanks and 73 Stephen G4SJP ___ 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] KX-1 BC interference on 20m
Given a 100 KW transmitter, with 2nd harmonics 40 dB down from the fundamental (which would be considered reasonably good suppression) is still 10 watts at the 2nd harmonic, I'm not sure about Europe but the Amateur radio *minimum* standard at HF for 1500 watts is about 45dB down for any spurious or harmonic. While there are lower suppression levels at lower power, it is set at a 50 milliwatt maximum limit. The USA commercial BC standard is in the -80dB range, I can't remember the exact amount. I just dealt with that with an AM BC station 100 miles from here that had a spur on 160 meters that was in the -40dBc range. In all cases there is an overriding regulation that says no matter what the level of spurious or harmonic, the unwanted emission cannot cause interference to a licensed service. This doesn't prevent BC stations from violating rules, especially in the USA with the poor enforcement and poor maintenance, but the rules themselves are pretty strict. -40dB would be considered very very poor suppression. 73 Tom ___ 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] KX-1 BC interference on 20m
My thought is that the problem was caused by one or more of the natural spurious responses of the KX-1's receiver, not by some harmonic or spur generated by the BC transmitters themselves. BC transmitter harmonics might also be generated and heard if you had a rusty bolt problem caused by say a nearby fence, and the BC signals were strong enough. 73, Geoff GM4ESD Stephen Prior wrote on Monday, August 25, 2008 at 2:07 PM As I have mentioned before, I really enjoyed using the KX-1 on holiday in Europe this year but found that there were several broadcast stations appearing across 20m from about 14.20MHz upwards. I was using a roughly 5/8 wave vertical antenna with counterpoise and the internal ATU. Is this normal operation, or should I delve into the manual for alignment procedures? I am at a disadvantage in that I did not build the unit. The radio suffered a pretty bad knock whilst camping and I am wondering if something is adrift. ___ 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] KX-1 BC interference on 20m
Hi Geoff Well, I left out perhaps the most important info in that I don't have the problem on the same antenna with either the K2 or K3. I have mentioned the knock that the KX-1 received. I have subsequently found that the knock has broken the soldered joints holding both earth pins of the bnc socket- looking at them I'm pretty sure they were dry joints anyway. Having resoldered them, most of the BC qrm has gone, but not all. I have the same effect both here in the UK and in Portugal and France, so it's not a nearby fence in this case :-)) I'm sure that I did not experience the problem when I first had the radio and I am wondering if there are further joints which have been disturbed- my son caught the coax with his legs as he walked past my tent and the radio flew off the table really very quickly! I was pleased to find that it still worked. 73 Stephen G4SJP On 25/08/2008 19:21, Geoffrey Mackenzie-Kennedy [EMAIL PROTECTED] wrote: My thought is that the problem was caused by one or more of the natural spurious responses of the KX-1's receiver, not by some harmonic or spur generated by the BC transmitters themselves. BC transmitter harmonics might also be generated and heard if you had a rusty bolt problem caused by say a nearby fence, and the BC signals were strong enough. 73, Geoff GM4ESD Stephen Prior wrote on Monday, August 25, 2008 at 2:07 PM As I have mentioned before, I really enjoyed using the KX-1 on holiday in Europe this year but found that there were several broadcast stations appearing across 20m from about 14.20MHz upwards. I was using a roughly 5/8 wave vertical antenna with counterpoise and the internal ATU. Is this normal operation, or should I delve into the manual for alignment procedures? I am at a disadvantage in that I did not build the unit. The radio suffered a pretty bad knock whilst camping and I am wondering if something is adrift. ___ 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] KX-1 BC interference on 20m
Hi Stephen, It might help if you could identify the SW stations you're hearing, and find out what frequency they're on. What you could be hearing is a very strong signal on the receiver's image frequency, and the only thing you could do would be to add more selectivity to the front end to attenuate the signal on the image frequency. Ask Elecraft, they would know. 73, ed - k9ew www.k9ew.us\ ___ 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] KX-1 BC interference on 20m
Stephen and Ed, I was thinking along those same lines. On 20 meters, the KX1 LO signal is below the RF signal, so a strong BC station in the 4.1 to 4.3 MHz range could push itself through and be heard on the upper end of the 20 meter band. If you have no stations on that part of the spectrum, you can likely reject the assumption of an image response. The KX1 design faced many challenges in order to stuff all that performance in a small space, so the design is a bit of a compromise. The front end suffers from responses in the presence of strong RF energy just like any other Gilbert cell mixer connected in the receiver front end (with no RF amp stage for isolation). My understanding is that the Gilbert cell mixer can generate 'funny stuff' in the presence of strong RF energy fields like might be found in Europe - in reading EMRFD, I find that Wes Hayward does not even recommend the gilbert cell mixer for use in receivers that will be used on the Eastern side of the US for this very reason. In addition, the DDS does have some spurs that can be mysterious - if the offending signal tunes more quickly than normal signals, you are likely hearing the result of one of the DDS spurs. The KX1 is a good design, but it just is not perfect in all ways. You may be hearing the result of one of these imperfections - OTOH, you *could* have a problem there. Comparison with another KX1 under the same circumstances is one way of telling whether a problem exists or it is just one of those design compromise situations. 73, Don W3FPR Ed - K9EW wrote: Hi Stephen, It might help if you could identify the SW stations you're hearing, and find out what frequency they're on. What you could be hearing is a very strong signal on the receiver's image frequency, and the only thing you could do would be to add more selectivity to the front end to attenuate the signal on the image frequency. Ask Elecraft, they would know. 73, ed - k9ew www.k9ew.us\ ___ 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 No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.6.7/1631 - Release Date: 8/24/2008 12:15 PM ___ 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
