K3 and KAT500 low power problems

[ejkkjh]

I have been doing some testing using WSJT-X, and other digital modes, with my K3 an my Signalink USB.
Receive works pretty good with decodes on WSJT-X at –19 to an occasional decode at –24.
On transmit using various digital software and modes, when I transmit at 5 watts the KAT500 has problems.
I tune up with 20 watts, all is fine, 1.0 swr.  But then I transmit with power at around 5 watts, in a digital transmission, the KAT500 starts a tuning cycle, then ends in a fault condition.  If I transmit with the power above about 10 watts, clear up to 100, everything works perfect?
I have tried this with various modes and digital programs, does it every time, on several different bands.
I prefer to run at 5 watts but I guess the easy solution is to run at 15 or 20 watts.
Any help or ideas would be appreciated.
Thank you 73
Emory  WM3M
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[mcduffie]

> I tune up with 20 watts, all is fine, 1.0 swr.  But then I transmit with power at around 5 watts, in a digital transmission, the KAT500 starts a tuning cycle, then ends in a fault condition.  If I transmit with the power above about 10 watts, clear up to 100, everything works perfect?

As previously recommended, you should not leave it in auto after tuning.  After
tuning, use manual mode so that it doesn't "go hunting".  This seems to be
especially true for CW/SSB, where power varies between zero and X watts.

Gary
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[Eric Swartz - WA6HHQ]

Hi Emory,

The KAT500 design is optimized for 10W through 1000 W operation, with better
tuning above 20W. It is not designed as a QRP tuner.  It can be used at 5W
levels, thought we do not guarantee this, if it is pre-tuned first at higher
power (20 W +) on each freq and then run in manual mode (which still auto-reads
the frequency and selects the correct prior tune for that range).  That should
prevent most false frequency counts at 5W.

Your WSJT power envelope will drop well below its 5W peak during transmission,
causing the frequency counter to get multiple incorrect counts and generating a
spurious re-tune when operating in auto-tune mode. The frequency counter in the
KAT500 works best during regular TX for signals that are primarily peaking above
the 20W range.

Also, make sure you have the latest KAT500 firmware loaded in your unit. We have
made significant improvements to the frequency counting and tuning algorithms
since our earliest shipped units.

Personally, even when running my KPA500 with the KAT500 at 500 W operating
levels, I use auto-tune mode and 20-50 W to train the tuner to my antennas on
each frequency with a CW carrier, and then run it in manual mode at 500+ W from
that point for normal operating.

73,

Eric
elecraft.com

On 11/13/2014 2:30 PM, [hidden email] wrote:

> I have been doing some testing using WSJT-X, and other digital modes, with my K3 an my Signalink USB.
> Receive works pretty good with decodes on WSJT-X at –19 to an occasional decode at –24.
> On transmit using various digital software and modes, when I transmit at 5 watts the KAT500 has problems.
> I tune up with 20 watts, all is fine, 1.0 swr.  But then I transmit with power at around 5 watts, in a digital transmission, the KAT500 starts a tuning cycle, then ends in a fault condition.  If I transmit with the power above about 10 watts, clear up to 100, everything works perfect?
> I have tried this with various modes and digital programs, does it every time, on several different bands.
> I prefer to run at 5 watts but I guess the easy solution is to run at 15 or 20 watts.
> Any help or ideas would be appreciated.
> Thank you 73
> Emory  WM3M
> ______________________________________________________________
> Elecraft mailing list
>

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[Jim Brown-10]

On Thu,11/13/2014 2:30 PM, [hidden email] wrote:
> On transmit using various digital software and modes, when I transmit at 5 watts the KAT500 has problems.
> I tune up with 20 watts, all is fine, 1.0 swr.  But then I transmit with power at around 5 watts, in a digital transmission, the KAT500 starts a tuning cycle, then ends in a fault condition.  If I transmit with the power above about 10 watts, clear up to 100, everything works perfect?

The reason the KAT500 is misbehaving is that it is a high power antenna
tuner. Last I looked, 10W was the minimum power for tuning. That's why
Gary advised you to take it out of Auto mode once you've trained it with
higher power and stored settings.

73, Jim K9YC
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[k6dgw]

On 11/13/2014 4:10 PM, Jim Brown wrote:

> The reason the KAT500 is misbehaving is that it is a high power antenna
> tuner. Last I looked, 10W was the minimum power for tuning. That's why
> Gary advised you to take it out of Auto mode once you've trained it with
> higher power and stored settings.

Mine wants to see a tune power of 20 - 25W for reliable tuning.  I
"trained it" on each segment, and normally run it in MAN mode.  It
recalls the settings almost instantly.  Only annoyance for me is when it
rains, the window-line changes characteristics just a little.
California is in a deep drought however, so rain is scarce and this is a
problem with *my* antenna system, not the KAT500.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the 2015 Cal QSO Party 3-4 Oct 2015
- www.cqp.org


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