[Elecraft] KPA1500 problem

[Jim Fitzpatrick]

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.

73

Jim WI9WI


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