GM Joe, It can't be solved. The SSB and/or Data at that AF MARS frequency is just slightly below the band pass filter change over to the 5.3 bandpass filter on the KPA500. That means that when you are on SSB, part of your rf envelope crosses over to the 5.3 band filter which causes the amp to switch to the higher bandpass (5.3) and when the rf at the frequency stops, the amp switches back to the 3.5 bandpass. It is not that noticeable at SSB operations because most men's vocal range does not stay or reach up high enough to trigger the switch. On data, however it's a different story. Since the M101 waveform has a bandwidth of 2.8 KHz, your signal is almost always going to cross over that "flash point" causing the amp to go from OPER to STBY and vice-a-versa. There is a slight delay in the switching because of what I believe, are the high and low thresh holds of the filter frequency change point. There is also some delay in the changeover since again, what I believe is a hardware/software operation which says "I know you have change to a higher/or lower frequency, but I am not going to change to the correct band pass filter until - say 100 milliseconds later, because you might not have meant to do this". That's just a rhetorical guess on my part.
I brought this problem up with Elecraft some time ago so they know about the MARS Radio. Elecraft said there could be a software solution to move the trip points up a little bit. There were not, however, going to do it because the demand for the change is too low, there would be a lot of effort to test the modification and finally, it would be a another parallel version of the product to maintain. Hope this helps With best regards, Jerry, W1IE, AFA3GK -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Joe Rogers Sent: Monday, November 14, 2022 21:00 PM To: elecraft@mailman.qth.net Subject: [Elecraft] KPA500 Shifting Bands without any change in K3 Frequency I am operating the KPA500 KAT500 power combo with the K3. The combination works great and normally makes frequency and antenna changes really simple. I operate on MARS frequencies and normally all works just fine outside of all the amateur bands with the KPA500/KAT500/K3 there is, however, one frequency where there is an issue. When transmitting at about 4.5 MHz using SSB or digital modes, using the KPA500/KAT500/K3 combination, the band indication shoes the KPA500 spuriously shifting back and forth between 3.5 and 5.3 MHz bands. This also affects the amplifier output power. I can also hear what sounds like contact/relay cycling. This makes the combo unusable on this frequency. How can I resolve this problem so that the KPA500 is usable on this frequency? 73 Joe AJ1Y ______________________________________________________________ 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 w...@jetbroadband.com -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Joe Rogers Sent: Monday, November 14, 2022 21:00 PM To: elecraft@mailman.qth.net Subject: [Elecraft] KPA500 Shifting Bands without any change in K3 Frequency I am operating the KPA500 KAT500 power combo with the K3. The combination works great and normally makes frequency and antenna changes really simple. I operate on MARS frequencies and normally all works just fine outside of all the amateur bands with the KPA500/KAT500/K3 there is, however, one frequency where there is an issue. When transmitting at about 4.5 MHz using SSB or digital modes, using the KPA500/KAT500/K3 combination, the band indication shoes the KPA500 spuriously shifting back and forth between 3.5 and 5.3 MHz bands. This also affects the amplifier output power. I can also hear what sounds like contact/relay cycling. This makes the combo unusable on this frequency. How can I resolve this problem so that the KPA500 is usable on this frequency? 73 Joe AJ1Y ______________________________________________________________ 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 w...@jetbroadband.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
