[Elecraft] KPA100/KAT100 on 160 Hi Current

Thu Dec 7 13:31:00 EST 2006

Hi Don,

thank you very much, I will definitely take a look at
that. It certainly is easy to miscount a densely wound
toroid when distracted.

Cheers,

Julius
n2wn

--- Don Wilhelm <w3fpr at earthlink.net> wrote:

> John, Julius,
> 
> The normal thing to look at in a high current
> situation is the low pass
> filter.  Check both on the base K2 and the KPA100. 
> First thing is to count
> the turns on the toroids - count only the turns that
> pass through the center
> of the core or you might end up with an extra turn.
> 
> On the 160 meter band, one extra turn is all it
> takes to create a high
> current situation because the cutoff frequency of
> the LPF moves down into
> the 160 meter band and shunts some of the signal to
> ground.
> 
> The KAP100 LPF is easy to sweep with an antenna
> analyzer - connect the
> ribbon cable to the K2 and select the band of
> interest, put a 50 ohm
> resistor into the input cable and attach the
> analyzer to the SO-239.  If you
> do not find a low SWR throughout the band, the LPF
> is to blame.
> 
> 73,
> Don W3FPR
> 
> > -----Original Message-----
> > From: elecraft-bounces at mailman.qth.net
> > [mailto:elecraft-bounces at mailman.qth.net]On Behalf
> Of John Reiser
> > Sent: Thursday, December 07, 2006 10:43 AM
> > To: J F; Elecraft Discussion List
> > Subject: Re: [Elecraft] KPA100/KAT100 on 160 Hi
> Current
> >
> >
> > Hi Julius,
> >
> > Both my K2/100s, #4970 and #5570 exhibit excessive
> current draw on 160
> > meters, as indicated by the ammeter on my 30 watt
> Astron PS.  It
> > gets up to
> > 27 or 28 amps.  I use a 30 amp fuse.  In every
> other respect, my two
> > K2/100's work perfectly.  Current draw on all the
> other bands is
> > less than
> > 20 amps.
> >
> > I don't have an antenna for 160, so I never
> transmit on that band anyway,
> > and this is not a big problem for me.  Still,
> being a bit of a
> > perfectionist, it bothers me that it exists.
> >
> > I mentioned it on the reflector a while ago. 
> Someone said they
> > had the same
> > experience, but had no solution.  Someone else
> suggested that I
> > retune the
> > 80 meter bandpass filter to represent a compromise
> between 80 and 160.  I
> > tried that, but the excessive current draw
> continued regardless of the
> > bandpass tuning.  (Could it be due to the KPA100
> going into
> > oscillation at
> > the 160 frequency?)
> >
> > When I saw your post, I became hopeful that it
> might evoke a
> > response from
> > someone who had come up with the definitive
> solution.  But so far there
> > hasn't been any.
> >
> > Good luck and 73,
> >
> > John, W2GW
> >
> > ----- Original Message -----
> > From: "J F" <phriendly1 at yahoo.com>
> > To: "Elecraft Discussion List"
> <elecraft at mailman.qth.net>
> > Sent: Wednesday, December 06, 2006 5:49 AM
> > Subject: [Elecraft] KPA100/KAT100 on 160 Hi
> Current
> >
> >
> > > Well ARRL 160 is history now.
> > >
> > > As usual, with the K2 I heard more than I could
> get to
> > > hear me ;o) Evidently I heard and worked more
> than
> > > some of the local contesters with "other" brand
> > > equipment heheh.
> > >
> > > Anyway I have a problem... I use the KPA100 with
> the
> > > KAT100, and there may be no connection between
> the
> > > two, to stretch the bandwith of my antenna. If I
> set
> > > the K2 for 100 watts (or just twist the knob far
> > > clockwise), the ALC does not kick in. In a key
> down
> > > situation, the current keeps climbing until the
> fuse
> > > blows. If I set it for 99 watts (I realize this
> is not
> > > that precise) the ALC does function somewhat.
> I've not
> > > tried it with a dummy load. The antenna was
> fairly
> > > well matched (1.2:1 at it best point)and has a
> current
> > > balun on it. So this really shouldn't be
> happening. Do
> > > I have a problem with the KPA?
> > >
> > > Thanks,
> > >
> > > Julius
> > > n2wn
> > >
> > >
> > >
> > >
> >
>
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