[Elecraft] K3 - SWR Indication

[Steve Ellington]

Geoff
Try putting a 50 ohm dummy load in line and see if the K3 and your ext. 
meters read the same swr. This will take reactance and inbalance out of the 
picture.

Steve Ellington
N4LQ at carolina.rr.com
----- Original Message ----- 
From: "Geoffrey Downs" <geoffrey at downs.globalnet.co.uk>
To: <elecraft at mailman.qth.net>
Sent: Monday, May 04, 2009 10:14 AM
Subject: Re: [Elecraft] K3 - SWR Indication


> ----- Original Message ----- 
>
> From: "Steve Ellington" <n4lq at carolina.rr.com>
>
>
>>It appears that your coax does not exactly match the impedance of your
>>dipole (It rarely does)....
> -------------------------------------
>
> Thank you Steve for your comments. I fully accept about a probable 
> mismatch
> between dipole and coax (and of course the performance of the antenna
> remains to be seen), also that there are many factors affecting SWR and 
> that
> sampling at different points along the coax will produce different results
> if there is reactance in the load. In this case the antenna feeder was
> connected to the LP100A about 2.5 inches down the line from the ANT 1
> socket. To my mind that seems a short length to account for an SWR
> difference at 7 Mhz as big as 1.2:1 (K3) vs 2.0:1 (LP100A and MFJ 259B). 
> We
> all need to know what sort of load the rig or the amplifier is looking 
> into
> and a discrepancy like that is unsettling.
>
> All three measuring devices see no reactance and 1.0:1 at 7.145 MHz. What
> seems to happen is that as one moves up or down in frequency from that 
> point
> (and the load gains reactance) the K3 indication remains significantly
> lower than than other two. I doubt if 2.5 inches of coax would account for
> the difference and the MFJ259B, which agrees with the LP100A,
> connects to the antenna feeder at exactly the same point as the K3's
> ANT 1 socket so there is not even that extra 2.5 inches.
>
> It leads me to think that maybe my K3 is not measuring SWR as well as it
> should either due to a fault in my particular one or to the way it is set 
> up
> to work.
>
> 73 to all
>
> Geoff
> G3UCK
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html