[Elecraft] k3 SWR readings seem generous

[Jeff Kinzli N6GQ]

Mike, I see the same thing. My Autek says my antenna is 2.5:1, the K3
(#476) says 1.2:1 at the same frequency (numbers mentioned were on
40M).

My Palstar SWR meter pretty much agrees with the Autek.

-Jeff N6GQ

On Thu, Jan 1, 2009 at 17:47, Mike Scott <mike at paxsen.com> wrote:
> I have been working on antennas today and have a puzzle. I am finding that
> the K3 SWR indications are unbelievable generous.
>
> With my 40M inverted V fed with RG8X (50 ohm) coax I see that the K3 seems
> generous in the SWR indication on tune with ATU bypassed. I have noticed a
> slight change in SWR with K3 power setting so the following was taken with
> K3 tune power set to 100 watts. If I set it to 10 watts the discrepancy is
> greater...
>              SWR     SWR     SWR
> Freq.         K3      VA1     Daiwa
> 7.00 MHz     1.3      1.92    2.0
> 7.05 MHz     1.2      1.92    1.9
> 7.1 MHz      1.2      1.98    1.95
> 7.15 MHz     1.3      2.26    2.1
> 7.2 MHz      1.9      2.60    2.3
> 7.25 MHz     1.5      2.88    2.6
> 7.3 MHz      1.6      3.32    2.7
>
> The Daiwa is the CN-101L cross needle meter. The VA1 is the Autek Rx Vector
> antenna analyzer.  The VA1 does not have a tuned input so it is possible
> that it can be fooled by local broadcast stations. I don't suspect this
> issue here as there aren't any close by broadcast stations that I am aware
> of. The Daiwa and the VA1 tend to agree pretty well anyway. The K3
> measurements are the outliers. This antenna on a "Tenna Dipper" shows
> minimal SWR at 7.040 MHz, just where I tuned it a few years ago. The LED
> does not extinguish indicating higher than 1:1 SWR at the minimum. If you
> look at the numbers, I guess I don't believe the K3, Do you think my antenna
> is below 1.6 to 1 across the entire 40M band?
>
>
> So now on to 20M dipole fed with RG58 (50 Ohm Coax)...
> The Tenna Dipper fully extinguishes at 13.805 MHz indicating that my antenna
> is bit too long but is close to 1:1 at that frequency.
>
> Freq        K3     VA1     Daiwa
> 13.81       --     1.12    --
> 14.0 MHz    1.1    1.24    1.31
> 14.1 MHz    1.1    1.30    1.70
> 14.2 MHz    1.1    1.55    1.85
> 14.3 MHz    1.2    1.69    1.85
>
> RG58 may have some losses on this band so perhaps all of the SWR indications
> are generous, some more than others. The dipole is a low one and probably
> isn't 72 ohms at the feed point.
>
> Mike Scott - AE6WA
> Tarzana, CA (DM04 / near LA)
> K3-100 #508/ KX1  #1311
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>