Jim, No answers here, but email supp...@elecraft.com. I have heard of this sort of problem before, but do not know the answer.
73, Don W3FPR On 7/20/2018 8:54 PM, Jim Fitzpatrick via Elecraft wrote:
I received my new KPA1500 in mid April. After giving it a test drive and making a few QSOs here at home in Madison I took it up to our cabin in northern WI where it will live. I operated the Florida QSO party with it, as well as the ARRL VHF contest with no problems. I also made quite a few FT8 QSOs on 6 meters in casual operation. This past weekend I went up there for the IARU contest. I started on 40 meters and noticed no problems. Note that I do virtually all my receiving on 40 with Beverage antennas in the summer due to thunderstorm noise. After a couple of hours I went to 20. I thought that the band was awfully quiet and pretty dead. After a few hours I took a break. I was working people at a fairly good rate running about 1300 watts, but signals seemed very weak. Coming back from the break the band seemed much better. After a few minutes I noted that I had forgotten to take the amp out of standby and was running about 30 watts. So I put the amp in the operate position and all the signals disappeared. After a lot of putzing and futzing it appears that there is somewhere between 20 and 30 dB of attenuation in the receive path when the amp is in the operate position. I didn't notice it initially on 40 because I was using the Beverages. This appears to be the case on all bands. I am using resonant antennas and it is unaffected on transmit. It will put out full power on all bands with a low SWR. It doesn't matter if the tuner is in the circuit or not. So I took down the amp and for the rest of the contest I used my old amp, a Tokyo HiPower 550 without any problems. So I brought the whole thing back home and set it up here. I rebooted the firmware and then downloaded the newest firmware without any change in how it is behaving. There is no problem with the K3 or the other amp. The K3 works just fine with my KPA500 at home. So the bottom line is the KPA1500 has developed an attenuation of somewhere between 20 and 30 dB in the receive path (estimated from the S meter on the K3 assuming an S unit is somewhere between 3 and 6 dB). I haven't done anything klutzy like leave the K3 with the receive antenna switch on with no antenna attached....I've done this before :-). I'd appreciate any advice or ideas.
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