[Elecraft] KAT500 Tuning issue

[Jerry Weisskohl]

Right now, I have the coax from the antenna directly connected to the
KAT500. I could try using my Delta-4 switch, have the coax go to that and
then a small run to the KAT500 to see if that makes a difference. The high
swr is an issue on 40 and 10 meters, however, ten is manageable, it's about
1.9 - 1 and I am working around the issue but using my 80 meter vertical on
20 meters. So this is not a "show-stopper" but just wanted to understand
 why it was happening.

Jerry - AC4BT


On Sat, Dec 8, 2012 at 4:14 PM, Vic Rosenthal <k2vco.vic at gmail.com> wrote:

> If the feed line happens to be near an even multiple of a half wavelength
> the impedance will be very high and there will be a voltage loop (HV point)
> at the tuner. As someone else noted, losses would also be very high, so
> using a 40m coax fed dipole on 20 is a poor idea.
>
> Vic k2vco
>
> On Dec 8, 2012, at 12:37 PM, "hawley, charles j jr" <c-hawley at illinois.edu>
> wrote:
>
> > Now that I think about it, if you have a different feedline length
> depending on tuning from the output of the KAT or tuning from the output of
> the K3 with both in line, that may make enough difference in the required
> values to tune.
> >
> > Chuck, KE9UW
> > Lionel Trains, TCA, LCCA, LRRC
> > aka Jack, BMW Motorcycles BMWMOA #224
> >
> > ________________________________________
> > From: elecraft-bounces at mailman.qth.net [elecraft-bounces at mailman.qth.net]
> on behalf of hawley, charles j jr [c-hawley at illinois.edu]
> > Sent: Saturday, December 08, 2012 2:33 PM
> > To: Jerry Weisskohl; Elecraft at mailman.qth.net
> > Subject: Re: [Elecraft] KAT500 Tuning issue
> >
> > One thing I ran into with an automatic "hi powered" tuner is that the
> firmware does not allow all the otherwise available values of the
> components on certain bands. This is done in the case of the MFJ tuner I am
> using (now until the KAT arrives) on 40 Meters so that the voltage and
> current limits are not exceeded when handling full rated power. I don't
> know if the KAT500 has this implemented or if in the case of the higher
> power capability, it just doesn't have quite the range of the 100 watt
> tuner in the K3.
> > As was mentioned in a similar thread, you might experiment by changing
> your feedline a few feet plus or minus to find a more satisfactory matching
> situation on some bands.
> >
> > Chuck, KE9UW
> > Lionel Trains, TCA, LCCA, LRRC
> > aka Jack, BMW Motorcycles BMWMOA #224
> >
> > ________________________________________
> > From: elecraft-bounces at mailman.qth.net [elecraft-bounces at mailman.qth.net]
> on behalf of Jerry Weisskohl [jweisskohl at gmail.com]
> > Sent: Saturday, December 08, 2012 1:57 PM
> > To: Elecraft at mailman.qth.net
> > Subject: [Elecraft] KAT500 Tuning issue
> >
> > I believe I have run into a problem with the KAT500 tuner and wanted to
> > mention it to see if anyone else is experiencing the same issue. I just
> > received the KAT500 tuner  and the KPA500 amp and got it up and running
> > with my K3. The KPA500 works great but I am finding that the KAT500 is
> > unable to tune my 40 meter wire dipole on 20 meters. The best it can do
> is
> > 3.75 - 1 swr which trips the FAULT light on the KAT500. The internal
> tuner
> > in the K3 has been able to tune this antenna on all bands without issue.
> > Also the KAT500 is unable to tune 28400 below 2.5 - 1 while the internal
> > tuner in the K3 has no problems tuning that frequency. I have two
> antennas,
> > my other one is a 80 meter vertical so I switch to that for 20 meters
> but I
> > don't understand why the KAT500 is unable to tune certain frequencies
> when
> > the internal tuner on the K3 is able to do so.
> >
> > I called Elecraft and spoke to David who had me take the KPA500 out of
> the
> > picture by connecting the KAT500 directly to the K3. I had the same
> > results. David then sent me the latest unofficial KAT500 firmware 1.18
> > which I installed. It did not make any difference.
> > David had me try tuning using the utility, again no difference and still
> > unable to tune 20 meters below 2.75 - 1 on my 40 meter wire dipole.
> >
> > In general I am finding that the internal tuner does a much better job
> > tuning my antennas then the KAT500. I wonder if anyone else is
> experiencing
> > the same problem.
> >
> > As far as the settings on the K3 I am using the following:
> > COnfig:PWR Set = Per Band
> > COnfig:Tune PWR = 15
> >
> > I guess I will hope that this can be addressed through a later firmware
> > release. Meanwhile, the KAT500 is the weak link in my system. The KPA500
> is
> > fantastic, just need to resolve this tuner issue.
> >
> > Jerry - AC4BT
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