Date: Sun, 11 Jun 2017 16:53:44 +0000
From: Bill Turner <dezrat@outlook.com>
To: Amps group <amps@contesting.com>
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 http://myantennas.com/wp/product/cmc-230-5k/ 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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