[Elecraft] Sherwood's receiver performance table updated

[James Rodenkirch]

Wow....lots of good stuff emanating from this discussion - tnx to all for participating....

For Jerry - there are other reasons for employing an ATU in the shack - e.g., using open wire line feed line from the antenna back to the xmtr. 

_____________________________________
From: Jerry <ajermo at carolinaheli.com>
Sent: Wednesday, April 27, 2016 10:10 AM
To: Ken K6MR
Cc: Jim Rodenkirch; elecraft at mailman.qth.net
Subject: Re: [Elecraft] Sherwood's receiver performance table updated

I always thought the ATU in the shack was specifically to allow operation where there's an impedance mismatch (not necessarily non-resonant) specifically to protect solid state equipment from the high voltages that can be present.

Obviously an antenna system can be resonant and still not match impedance of the feed line and/or Radio.

Sent from my iPad

> On Apr 27, 2016, at 11:36 AM, Ken K6MR <k6mr at outlook.com> wrote:
>
> “P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
> make it "ok" to have the ATU in the shack while operating an antenna on
> multiple bands....what technical evidence of that posit do you have to
> share????”
>
> Jim:
>
> Google “transmission line bounce diagram”. This is a simple concept easily proven by mathematics.
>
> On a practical level, this is the concept behind the use of open wire feed lines. It’s been done for decades. The type of feed line does not change the theory.
>
> Ken K6MR
>
>
>
>
>
>
> From: Jim Rodenkirch<mailto:rodenkirch_llc at msn.com>
> Sent: Wednesday, April 27, 2016 06:21
> To: elecraft at mailman.qth.net<mailto:elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Sherwood's receiver performance table updated
>
> "It all depends" is/was the premise for my reply, Don.
>
> If new and old hams don't understand the potential problems with long runs
> of coax to/from an antenna they want to operate on multiple bands and an ATU
> in the shack they will be surprised at how inefficient their system is.
>
> P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
> make it "ok" to have the ATU in the shack while operating an antenna on
> multiple bands....what technical evidence of that posit do you have to
> share????
>
> Note 1: I had a 43' vertical with top loading wires in a NORD-style config
> with my external ATU at the base of the vertical and 120' of coax back to
> the shack ---- never saw a VSWR delta of more than .2 between what was
> "seen" at the input to the tuner and what was "seen" at the xmtr while
> operating on 160 through 20 meters.
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-s-receiver-performance-table-updated-tp7616652p7616802.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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