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Re: [RFI] Resolution of RFI into the receiver

To: Rfi@contesting.com
Subject: Re: [RFI] Resolution of RFI into the receiver
From: "Gary Smith" <Gary@doctorgary.net>
Reply-to: Gary@doctorgary.net
Date: Fri, 12 Dec 2008 09:16:30 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
> Congratulations to KA1J for caring about the quality of his  
> transmitted signal, and for diagnosing the source of the problem.
> 
> Bud, W2RU 


Thanks Bud,

It was driving me bats and was not making immediate sense. It 
confounded me long enough I ordered an Elecraft K3 kit (delivery next 
week) in a final gasp at "possibly" resolving the issue. I'm still 
happy to have the K3 as it's a markedly better radio but I would have 
probably held off a bit longer otherwise.

And yes, I have indeed seen the drifting swr but only when connected 
to the amplifier in operational mode. I have a Butternut HF9V, an 80M 
inv-L and a 160 inv-L all connected to the same radial plate which 
has 40+ 135' radials on a salt marsh. The 160 L has a pair of 
parallel doorknobs, the 80 L has a beater vacuum variable in line and 
the HF9V is what it is  and works well. a remote antenna switch 
selects which antenna is to be used. 

I couldn't understand why I was getting such a large swing in SWR as 
the tuned inputs to my Titan amp worked fine before and... the 
antennae I have are all resonant 1:1 at the feed point and when 
running barefoot in the shack. Thanks Bud for filling in that 
unexplained quandry. I have two radios at present; A corsair II and 
an Omni V. I should note the Omni suffered the SWR issue and the 
Corsair did not. Both radios experienced major difficulties with the 
amplifier.

FWIW, I was amazed I could get so much power out from these two 
3CX800A7 tubes (2.5KW+) and I had to keep bringing the drive back to 
keep it harnessed. It was because of the rfi into the radio that was 
causing this and now that the problem is resolved, the amplifier is 
as predictable as it should be. @ 2KW max. As I usually run around 
800W when QRO, the top end of power I can get is of no interest 
except that I surely was running the dirtiest station I have ever had 
and all that "extra power" was illegal garbage my station was 
spending unbeknownst to me.

I have to say I bet there's a lot of people having the same problem & 
don't know it. I hear a lot of garbage signals on the air & wonder 
how many of them are caused by this same problem. 

Gary
KA1J
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