Hi Barry,
I think what I am seeing is related to your experience. I ran through some
additional testing. I see perhaps some slight differences between ANT1 and ANT2
positions as far as SWR readings, but nothing significant, at least on 40
meters.
I do now see something I’m even more puzzled over. While collecting SWR
readings into a dummy load on 10 meters, I initially did see a high (2.0:1)
reading on the K3 meter. I switched in the K3 tuner, and brought the SWR down
to 1:1. But when I then bypassed the tuner, the low 1:1 SWR remained. This
was true for either ANT1 or ANT2. I really don’t understand that.
So back to 40 meters, where I first noticed the high SWR anomaly. I
thought I would try the tuner again, and then bypass it, to see if SWR would
stay low on the K3 meter as it did on 10 meters. It did not. So I still have
the anomaly on 40 meters, and it is the same on either ANT1 or ANT2 positions.
To summarize:
1. SWR using a dummy load on 40 meters remains constant using an external
LP-100A meter, but varies greatly using the K3 meter. As you tune up in
frequency on the 40 meter band, the SWR on the K3 meter rises to almost 3:1,
and the K3 output power drops back significantly.
2. Antenna tuner settings appear to “stick” on 10 meters, even when the tuner
is bypassed.
I believe some users, assuming there are others that have K3s which would
exhibit this behavior, may not have noticed this anomaly. I do believe it may
be responsible for what some users have noticed when using their K3 with an amp
such as the KPA1500. That is, power overshoot. I suspect the K3, at least for
me on 40 meters, is folding back power in response to a false SWR reading, and
this can be seen in how the KPA1500 amp correspondingly drops back in power as
the user transmits. That is perhaps why (again, for my situation) I see the
power overshoot only on 40 meters when using my KPA1500.
--Ed—
Sent from Mail for Windows 10
From: Barry Simpson
Sent: Monday, January 21, 2019 1:51 AM
To: Ed G; Elecraft Mailing List
Subject: Re: [Elecraft] K3 SWR Question3
Hi Ed
I recall having had a similar experience with my K3 some years ago, although it
wasn't on 40m. I think it was either 10 or 12m and related to an antenna
connected to the ANT 1 socket.
Eventually I tracked it down to having previously had an antenna connected to
the ANT 2 socket and having used the ATU in the K3 to tune it at that time
although I think that there was no antenna on ANT 2 when the problem cropped up.
I believe that the feed through between ANT 1 and 2 sockets was sufficient to
give a false SWR reading on the K3.
It might be worth investigating this and possibly swapping over your
antenna/dummy load to the ANT 2 socket to see what happens.
I think I eventually just retuned the ATU on ANT 2 with a dummy load in place
and the problem went away.
Good luck.
Barry VK2BJ
On Mon, 21 Jan 2019 at 04:17, Ed G <[email protected]> wrote:
Hello,
My K3 is exhibiting some SWR meter behavior I don’t quite understand. To
eliminate any possible effects of antennas or cabling, I hooked a Palstar DL2K
dummy load directly to the K3 antenna connector. All bands except 40 meters
seem fine, with SWR reading as you would expect with a dummy load. The anomaly
I am seeing is that SWR as shown on the K3 meter looks fine at 7.01 MHz
(approx. 1.2:1), but as I go up in frequency, the SWR as shown on the K3 meter
rises. When I transmit into the dummy load on 7.298 MHz, the K3 meter reads
almost 3:1. I can switch in the K3 internal tuner and bring the SWR down to
1:1.
I also tried an older Cantenna dummy load with the same puzzling results.
Any ideas as to what may be causing this 40 meter only problem? I first
noticed this problem during NAQP SSB when using my Steppir, which of course
retunes itself as I change frequency. When going from the low part of the phone
band to the high part on 40 meters, I noticed SWR increasing on the K3 meter,
even though it was not increasing and stayed at 1.2:1 on my inline LP-100A.
The K3 also started to fold back power. That prompted me to do the further
testing with the dummy load as I discussed above.
--Ed—
Sent from Mail for Windows 10
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