Hello Tim and all,
What's the reasoning behind placing the choke at the amp output
as opposed right at the transceiver?
73,
Larry K4AB
On Thu, Apr 8, 2021 at 10:45 PM Tim Duffy <k3lr@k3lr.com> wrote:
> Hello Alex,
>
> I can tell you that this test opened my eyes to how noise is propagated to
> our radio receivers. Like K9YC, W1HIS and many others I have embraced these
> findings. There is a reason the noise floor here at K3LR is below S0 on all
> bands. This is science - nothing more.
>
> I have significant common mode impedance chokes at every antenna feedpoint
> and at the connection to each amplifier (11) - so end to end on the
> feedlines. The results speak for themselves.
>
> This is not a wives tale. Do your own research and report your results.
>
> 73
> Tim K3LR
> -----Original Message-----
> From: RFI [mailto:rfi-bounces+k3lr=k3lr.com@contesting.com] On Behalf Of
> alex@kr1st.com
> Sent: Thursday, April 8, 2021 3:21 PM
> To: Alan Higbie
> Cc: Rfi List
> Subject: Re: [RFI] Old wives tail, or true?
>
> Let me challenge that test because I'm not convinced that the test is
> valid.
>
> I watched that video and it only shows the signals before and after the
> choke has been applied, on the outside of the coax. The conclusion is
> then drawn that all those signals make it into the receiver and causes
> noise. Can someone explain why that would be a valid conclusion?
> Shouldn't he be showing that those signals are indeed making it into the
> receiver and then showing that the application of the choke indeed make
> these signals disappear?
>
> I mean, I can make such measurements on any cable attached to a receiver
> and would probably be horrified by what I would see, but that doesn't
> mean that those signals actually make it into the receiver and cause
> noise.
>
> Like someone else wrote, the best test is probably to apply the choke
> and if it doesn't make a difference, ask for a refund from DXE. :)
>
> This inquiring mind would like to know.
>
> 73,
> --Alex KR1ST
>
> On 2021-04-08 10:35, Alan Higbie wrote:
> > In 2019 K3LR presented such a test at the Dayton Contest University.
> >
> > Tim describes it @ 15:30 into the presentation.
> > Here is the YouTube link: https://www.youtube.com/watch?v=wd5B5qPHI_U
> >
> > The relevant slides are at pages 41050 of his Power Point presentation.
> > CTU 2019 14-K3LR-Contest-Station-Optimization-PLUSROTATOR.pdf
> >
> > 73, Alan K0AV
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