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[Amps] Ten-Tec Titan 10 Meter Input SWR

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Subject: [Amps] Ten-Tec Titan 10 Meter Input SWR
From: "Jim Thomson" <>
Date: Sun, 11 Jun 2017 10:22:53 -0700
List-post: <>
Date: Sun, 11 Jun 2017 16:53:44 +0000
From: Bill Turner <>
To: Amps group <>
Subject: Re: [Amps] Ten-Tec Titan 10 Meter Input SWR

------------ ORIGINAL MESSAGE ------------(may be snipped)

On Sun, 11 Jun 2017 09:38:54 -0700, VE7RF   wrote:

>##  On a related note,  why is it, when I increase the length of 50 ohm coax  
>from my drake amps to the xcvr, that the
>input swr rises ??   Its flat  with  4 ft or less.... but rises when say 5-8 
>ft is used.  Thats on all bands. 
>Jim   VE7RF    

<REPLY My understanding is that's a false reading caused by current flowing
on the outside of the coax braid. The true SWR does not change. 

73, Bill W6WRT

##  Ok, so what I require is a CM  choke between  xcvr + input of amp ?   I 
will try that, since I have a pair
of the   CM chokes with sky high 
RS, like  8-11 K ohms on 
all bands.  That higher indicated  input swr   happens regardless of what XCVR 
is used..even tube types..and also
using a dummy load.   And it also does it on all 4 x drake amps.   They used a 
simple PI net for each band..with a lot higher Q  than the SB-220,
judging by the value of the C1  + C2 caps used.   I will try adding the CM 
choke at the amplifier input end of the
coax cable.   Heck, I can put one at each end of the interconnecting coax. 

Jim  VE7RF 

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