[Elecraft] KPA100 over current on 160m

[Bob Henderson]

I like to keep my K2 S/N 997 up to date.  I fitted a KPA100 two years 
ago and routinely apply other enhancements as they arise.  Whilst at 
Dayton this year I bought the components to increase the tolerance of 
the KPA100 to hi SWR.  I have just completed fitting the modkit and have 
replaced the firmware with 1.09.  Having done so, I decided to check the 
power output of the K2/KPA100 against DC current input accross all 
bands.  As I expected, there is a variation of DC current input and RF 
output.  However, from 80m thru 10m old 997 produces 90-110W at 
nominally 20 Amps.  The big shock is that on 160m it produces 110W but 
draws a huge 30 Amps from the DC supply.  Concerned that I might have a 
problem with the LPF for 160m, I terminated the KPA100 LPFs in 50ohms 
and used my MFJ antenna analyser to check the SWR of the filter.  On 
160m it is around 1.2:1.  The filters for other bands are all 1.3:1 or 
less.  It doesn't seem like the problem is the LPF.  I wonder if any 
other KPA100 owners might have seen this problem or have a clue to its 
cause?

73  Bob, 5B4AGN