K2 Linear Amp Driving Power

[Roy Morris-6]

Twelve watts output from my K2/100 on 75 meters will drive my Alpha 99 amp to 1000 watts.  My other two transceivers have to put out approx 35 watts to get 1000 watts out (which is normal driving power for this amp to put out 1000 watts).  I am using the same amp input coax on all transceivers which is approx 6 feet in length.  The output of the linear goes to a AT4K tuner which tunes the coax feed line to 1:1.  All components are properly grounded.  I receive good audio reports with the amplified K2/100, so I don't think stray RF or a parasitic oscillation is causing this.  I can increase the length of the amp input coax, but I don't know what else I can do to normalize the drive power.  The amp has 50 ohm passive input.  The power displayed on the K2/100 is normal at all power levels and on all bands 160-10 meters and is verified with both the Bird 43 wattmeter and the Array Solutions Power Master meter.  Any ideas anyone?  Roy Morris  W4WFB
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[Don Wilhelm-3]

Roy,

A watt is a watt as far as the amp is concerned, and it could care less
whether the driving generator is a K2/100 or whatever brand transceiver.

Put your Bird wattmeter in-line between the transceiver and the amp, then
try driving to 1000 watts with the K2/100 and another transceiver - observe
the power on the Bird as well as the power indicated by the driving
transceiver in both cases.

If you do discover that the power indicated on the Bird is the same for both
transxeivers, then the wattmeter in the KPA100 may need to be calibrated
better.  But if there really is a difference in drive required from the
K2/100 vs. other transceivers, you should drag out a 'scope and do some real
investigation of the waveform purity from all your transceivers - you will
likely be looking for a parasitic from one of them.  Don't overlook RF
feedback problems.  Ideally you should operate the amp into a dummy load for
these tests to remove the RF feedback possibility from the situation.

73,
Don W3FPR

> -----Original Message-----
>
> Twelve watts output from my K2/100 on 75 meters will drive my
> Alpha 99 amp to 1000 watts.  My other two transceivers have to
> put out approx 35 watts to get 1000 watts out (which is normal
> driving power for this amp to put out 1000 watts).  I am using
> the same amp input coax on all transceivers which is approx 6
> feet in length.  The output of the linear goes to a AT4K tuner
> which tunes the coax feed line to 1:1.  All components are
> properly grounded.  I receive good audio reports with the
> amplified K2/100, so I don't think stray RF or a parasitic
> oscillation is causing this.  I can increase the length of the
> amp input coax, but I don't know what else I can do to normalize
> the drive power.  The amp has 50 ohm passive input.  The power
> displayed on the K2/100 is normal at all power levels and on all
> bands 160-10 meters and is verified with both the Bird 43
> wattmeter and the Array Solutions Power Master meter.  Any ideas
> anyone?  Roy Morris  W4WFB

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