K3 & KPA500 3 days in.

[greenacres113-2]

My K3 is 2.5 yr.s old. I never bothered with updates as I was happy with
the radio as is. When my friend WB4YDL  helped me get the amp going we
had to run the latest updates. There is a new one that must be run to be
able to use the amp. I am using the Elecraft interconnect cable.
.....
I discovered that after we had the KPA500 up & running my ATU TUNE & ANT
[ant 1 or 2] functions were off in the K3. I  had to go into the MENU &
turn on  those functions. They are back & working OK. I don't know if
this is just something that  happened  because I had never updated the
K3 or if that happens to all connecting the KPA500. It did not affect
the RX ANT function.
...
One curious note. My SWR on the 6m antenna is apx 1.4:1. Good enough for
the amp. I tapped ATU TUNE with the amp off & the K3 easily went to it's
normal  1:1 SWR. When I keyed the amp the SWR LEDs  are showing  apx
1.2/1.3:1 SWR.  The K3 reads 1:1 SWR either way.I don't know if it
actually is that or what. During xmit with the amp it shows better SWR
consistantly. Haven't tried the HF antennas yet.

K9IL
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[Rick Tavan N6XI]

You don't have a problem with your 6M setup - it's working well. When you
use the 100W K3 ATU with the amp bypassed, it sees the antenna as its load
and adjusts the match to let the K3 see a 1:1 SWR. When you put the amp in
line, the K3 sees the amp as its load, not the antenna. The SWR seen by the
K3 should be close to 1:1. The K3 tuner can and should be disabled. The amp
sees the untuned antenna as its load, including any inherent mismatch. The
SWR displayed by the amp won't necessarily be the same as what the K3 saw
without its tuner because of SWR metering calibration differences and
variations in apparent SWR along varying lengths of feedline. But the K3
tuner is irrelevant when the amp is in line. It can't change the SWR seen by
the amp and the amp can't change the SWR of the antenna. If you put a high
power tuner between the amp and the antenna, then it should be able to tune
out the SWR seen by the amp. Elecraft has announced a future KAT-500 (1000?)
that will do this or you can use a third-party product.

73,

/Rick

On Tue, Jun 21, 2011 at 7:39 AM, r miles <[hidden email]> wrote:

>
> One curious note. My SWR on the 6m antenna is apx 1.4:1. Good enough for
> the amp. I tapped ATU TUNE with the amp off & the K3 easily went to it's
> normal  1:1 SWR. When I keyed the amp the SWR LEDs  are showing  apx
> 1.2/1.3:1 SWR.  The K3 reads 1:1 SWR either way.I don't know if it
> actually is that or what. During xmit with the amp it shows better SWR
> consistantly. Haven't tried the HF antennas yet.
>
>
--
Rick Tavan N6XI
Truckee, CA
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[Bill K9YEQ]

I use solid-state amp with my K3.  With the amp on standby in circuit, I
tune, then activate the amp.  The K3 and amp work just fine.  Tuner memory
may be an issue when doing a QSY so disabling the tuner in that circumstance
would probably be of benefit.  Any losses added by the tuner are
insignificant at 1.5 KW amp output.  I usually ragchew in the evenings and
use my amp.  Otherwise, the amp is off for my other bands where I operate
QRP most of the time.

73,
Bill
K9YEQ



-----Original Message-----


You don't have a problem with your 6M setup - it's working well. When you
use the 100W K3 ATU with the amp bypassed, it sees the antenna as its load
and adjusts the match to let the K3 see a 1:1 SWR. When you put the amp in
line, the K3 sees the amp as its load, not the antenna. The SWR seen by the
K3 should be close to 1:1. The K3 tuner can and should be disabled. The amp
sees the untuned antenna as its load, including any inherent mismatch. The
SWR displayed by the amp won't necessarily be the same as what the K3 saw
without its tuner because of SWR metering calibration differences and
variations in apparent SWR along varying lengths of feedline. But the K3
tuner is irrelevant when the amp is in line. It can't change the SWR seen by
the amp and the amp can't change the SWR of the antenna. If you put a high
power tuner between the amp and the antenna, then it should be able to tune
out the SWR seen by the amp. Elecraft has announced a future KAT-500 (1000?)
that will do this or you can use a third-party product.

73,

/Rick

On Tue, Jun 21, 2011 at 7:39 AM, r miles <[hidden email]> wrote:

>
> One curious note. My SWR on the 6m antenna is apx 1.4:1. Good enough
> for the amp. I tapped ATU TUNE with the amp off & the K3 easily went
> to it's normal  1:1 SWR. When I keyed the amp the SWR LEDs  are
> showing  apx
> 1.2/1.3:1 SWR.  The K3 reads 1:1 SWR either way.I don't know if it
> actually is that or what. During xmit with the amp it shows better SWR
> consistantly. Haven't tried the HF antennas yet.
>
>

--
Rick Tavan N6XI
Truckee, CA
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