[Elecraft] Power Out of KPA100

[W3FPR - Don Wilhelm]

Steve,

Put in the new resistors Scott sent to you (yes, the 5600 pf capacitors can
stay) and then calibrate the wattmeters in the KPA100 and the KAT100 and you
should be all set.  If you can buy, beg, borrow or otherwise acquire a good
50 ohm non-reactive dummy load you will find the wattmeter calibration much
more accurate.  I recommend using an RF Probe to measure the RF Voltage at
the dummy load rather than relying on any wattmeter - even the best are
spec'ed for only 5% of full scale when properly calibrated, so on a 100 watt
scale, even the best can be off by as much as 5 watts - the run of the mill
wattmeters can only be trusted to 20% of full scale (20 watts possible error
on a 100 watt scale) until proven otherwise.

73,
Don W3FPR


> -----Original Message-----

> Hi all,
> I am wringing out my KPA100 and have come up with the following
> numbers.  I
> did do the 2 capacitor mod while building the KPA100.
> I used the dummy load in my MFJ-949E, which I measure at 56 Ohms.  I
> connected the K2 to a Mirage MP1 Wattmeter to the KPA100 in the
> EC2 case, to
> the KAT100, to the MFJ-949E.  I figured the KAT100 would offset the 50 Ohm
> deviation in the dummy load.  For the SSB measurements I used a
> Kenwood MC43
> mic.  The number in "" is the requested power from the K2.   For SSB, for
> this very scientific test ;o) I said "Ahhhhh" into the mic.
>
> SSB
> 80M	3773	100W	"80"
> 40M	7251	100W	"99"
> 30M	10114	90W	"110"
> 20M	14290	70W	"110"
> 17M	18136	100W	"90"
> 15M	21350	110W	"100"
> 12M	24950	100W	"110"
> 10M	28400	100W	"110"
>
> CW
> 80M	3600	105W	"60"
> 40M	7050	110W	"70"
> 30M	10115	98W	"110"
> 20M	14050	100W	"70"
> 17M	18080	100W	"70"
> 15M	21100	100W	"60"
> 12M	24900	100W	"60"
> 10M	28050	110W	"70"
>
> Scott at Elecraft sent me 2 new low inductance resistors just in
> case, but I
> already replaced the 2 caps with higher values (5600 pf), and didn't save
> the old caps.  But then again that was for a fix for 20M and 17M.
>
> I repeated the SSB 30M and 20M test without the KAT100 in line and got the
> same results.  So it looks like 30M and 20 M output is a little
> low on SSB,
> but is fine on CW.
>
> Any comments?
>
> Thanks,
> Steve, W2MY
>
>
>
>
>
>
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