[Elecraft] Sherwood's receiver performance table updated

[Phil Wheeler]

But this discussion seems to have evolved into 
something difficult to relate to the thread title. 
You might want to change the title!

Phil W7OX

On 4/27/16 10:25 AM, James Rodenkirch wrote:
> 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.