[TowerTalk] ? Yagi Interaction on 15m: KT34XA and XM240

[Michael Tope]

Hi Jeff,

Your MFJ-259 VSWR curve is very similar in shape to the KT34XA that we put up at
W6UE. Your actual VSWR values are a bit different, but the peaks and valley's are 
all in the same places. The measurement I made on UE's KT34XA were made before
we installed the 4 element 40. The antenna was by itself at 102' when the measurement 
were made. 

The interaction between the 34XA and the XM-240 should be linear with power unless 
you are heating up a balun or something like that. Do you have a separate coax run for
the XM-240? If so, try changing the shack termination from open to short to 50 ohm 
dummy load to see if the KT34XA VSWR changes. This will give you some idea of the
degree of interaction. If you have the separate feedline for the XM240, put a wattmeter on 
it in the shack to see how much power is being coupled in from the KT34XA. 

Also, what equation are you using to convert the W-4 power readings into  VSWR?

Mike, W4EF........................................

----- Original Message ----- 
From: "Jeff Maass" <jmaass@columbus.rr.com>
To: "towertalk Mail List" <towertalk@contesting.com>
Sent: Thursday, October 26, 2000 7:24 AM
Subject: [TowerTalk] ? Yagi Interaction on 15m: KT34XA and XM240


> What are the signs of interaction between tribanders and 40 
> meter yagis?
> 
> I recently installed a KT34XA at 69' and an XM240 at 79' (~10 feet
> separation). I'm seeing differences between the measurements 
> made with my MFJ-259 and a transmitter (90W and 1000W) with 
> wattmeter. You can see the measurements at: 
> 
> http://www.zing.com/album/?id=4293852949&p=4282913117&idx=69
> 
> Is it possible that the interactions are not measurable with the low-power
> signal of the MFJ-259, but clearly evident when running more power
> for the measurement?
> 
> Jeff Maass       jmaass@columbus.rr.com     Located near Columbus Ohio
>          USPSA # L-1192       NROI/CRO    Amateur Radio K8ND
>     Maass' IPSC Resources Page:  http://home.columbus.rr.com/jmaass
> 
> 
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