[Elecraft] K2/100, half power output on 17-10M

[Don Wilhelm]

Jeff,

In that case, review the soldering (and toroid lead stripping) in the 
wattmeter section.  See the KPA100 schematic sheet 1 on the right side. 
  T4 and components attached to it, U5 and components associated, and U6 
with its associated components.  Q10 and Q11 play a role in the scaling 
from low power to high power.

Do you have a problem at low power too?  Remove power from the KPA100 
and apply power only to the K2 coaxial power connector to investigate.

73,
Don W3FPR

Jeff Kinzli N6GQ wrote:
> Don, C31 is the new value, just replaced it a few weeks ago...
> 
> -J
> 
> On 4/7/07, Don Wilhelm <w3fpr at earthlink.net> wrote:
>> Jeff,
>>
>> In that case, what is the size of C31?  If it is the old .033 uF it must
>> be changed to the new .22 uF value.  You can get one from Elecraft when
>> they get back in the office, but if you have two .1 uF caps with a
>> voltage rating of 50 volts or more, you can parallel them for the time
>> being.
>>
>> 73,
>> Don W3FPR
>>
>> Jeff Kinzli N6GQ wrote:
>> > Don, thanks, it's the newest KPA100, just bought/built it about a
>> > month or two ago...
>> >
>> > -Jeff
>> >
>> > On 4/7/07, Don Wilhelm <w3fpr at earthlink.net> wrote:
>> >> Jeff,
>> >>
>> >> Before we give any answer, we need to know the level of the KPA100.
>> >> Did you build it from the manual Revision D or the earlier Rev C?
>> >> Another way of checking - do you have a toroid at L15 and is RFC10
>> >> present?
>> >>
>> >> It is not likely to be a sticking relay problem - that almost never
>> >> happens with the KPA100.
>> >>
>> >> 73,
>> >> Don W3FPR
>> >>
>> >> Jeff Kinzli N6GQ wrote:
>> >> > My K2/100 (#5945) has been working well lately, until I started
>> >> > noticing higher output at times, more pronounced with higher SWR
>> >> > antennas (i.e. it would more often spike it's output power if
>> >> > connected to an antenna with more than 1.3:1 SWR, the output power
>> >> > would rise to 140W).
>> >> >
>> >> > About the same time, I started noticing lower output power on 10, 
>> 12,
>> >> > 15, and 17M. Output remains full on 20, 30, 40 and 80M.
>> >> >
>> >> > Today I pulled the KPA100 apart, went though and checked and
>> >> > resoldered everything around the SWR bridge, and anything that 
>> looked
>> >> > remotely cold-soldered.
>> >> >
>> >> > Put it back together, same issue (well, at least the lower power
>> >> issue).
>> >> >
>> >> > With a setting of anything over 50W, the max output is 50-52W, as
>> >> > indicated on the K2 internal wattmeter, or my external wattmeter.
>> >> >
>> >> > Any ideas why I'd only get half power on half the bands (and this 
>> is a
>> >> > new occurrance, I was getting full power before).
>> >> >
>> >> > Thanks for any ideas,
>> >> >
>> >> > Jeff
>> >>
>> >
>>
>