KPA1500 problem

classic Classic list List threaded Threaded
1 message Options
Reply | Threaded
Open this post in threaded view
|

KPA1500 problem

john@kk9a.com
You probably need a replacement T/R module.  Were the pin diodes exposed to
super high SWR?

John KK9A



Jim Fitzpatrick WI9WI 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.

73

Jim WI9WI

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]