[Elecraft] KPA1500 problem

[Don Wilhelm]

Jim,

No answers here, but email support at 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.
>