[Elecraft] K2 and the KPA100 Power Fluctuation - Another Follow up

[Tom, W6WW]

Michael,

Thanks.  I think I will put in the 1K when I start the KPA100 and see how it
goes.  Right now, I am trying to kludge up an antenna to see if the basic K2
will get out for a first QSO.

73,
Tom, W6WW
K2 #3453


----- Original Message -----
From: "Michael Harris" <mike.harris@horizon.co.fk>
To: "Tom, W6WW" <tom@cwx.com>
Sent: Sunday, June 15, 2003 12:03 PM
Subject: Re: [Elecraft] K2 and the KPA100 Power Fluctuation - Another Follow
up


> Hi Tom,
>
> > Ah, but I am just finishing the K2 and haven't started the KPA100 yet,
so
> > don't know if I need it.  I was wondering if it made sense to do the mod
> to
> > the K2 before I finish it, or wait and see.
>
> Horns of a dilemma there..!
>
> Published numbers so far are: 1K0, 1K3 and 2K2 ohms.  I think it's
perfectly
> safe to go with the 1K0 substitution for R98.  The only thing you have to
> keep in mind is achieving no loss of power output on 10 metres.  In this
> respect it might be a good idea to build the K2 as supplied and then
change
> the R98 afterwards when you know the output on each band is normal.  Some
> people have had problems achieving 10W on 10 metres and had to sort that
> first.  After all, it is a very simple mod to make.
>
> One comment I would make is for tuning band pass filters an analogue power
> meter is better than digital, much easier to peak the output with a swing
of
> a meter than trying to absorb dancing digits.
>
> With the KPA100 the power calibration setting of R26 is critical and after
a
> rough alignment at 5W it is important to do go to a higher power, 50W is a
> good choice.  Life is difficult if the power is jumping up and down due to
> AGC stepping.
>
> Also, If you go the route of building the KAT100 then setting the power
> calibration of that is damn difficult with the power stepping between 17
and
> 22 watts when you are trying to set a voltage derived from a 20W signal.
>
> The problem is that if the ALC of the basic K2 is, for example, giving
0.1dB
> steps, fine enough control for anyone, by the time the KPA100 has added at
> least 10dB gain, the AGC steps are multiplied to 1dB per step.  This
> calculates out to close to the sort of power level fluctuation I, and
others
> were seeing.
>
> Best of luck,
>
> Mike VP8NO (IOTA SA-002)
> GQRP 10148
> QRP-Canada #57
> K2/100 #1400
>
>
>