[Elecraft] Feedline loss w/wo tuner

[Ron D'Eau Claire]

My first "radio book", the 1941 ARRL Radio Amateur's Handbook, mentions SWR
in passing, but nearly everyone used open wire feed lines before WWII that,
with their moderately high impedances (450 to 600 ohms), had rather low loss
at any SWR one was likely to encounter. So Ham concerns with SWR were mostly
academic and limited to the antenna "theory" discussions. 

The need for shielding to minimize TVI and the huge amounts of very cheap
"war surplus" coaxial cable after WWII changed the feed line landscape very
quickly. The low impedance of that coax (50 ohms) meant that feed line
losses were no longer insignificant although it took a number of years for
coax to become the dominant feed line. By the 1950's QST was publishing
designs for homebrewing an SWR Meter several times a year. 

73, Ron AC7AC

 

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Fred
Jensen
Sent: Wednesday, April 27, 2016 1:35 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Feedline loss w/wo tuner

Indeed!  I don't remember when the acronym "SWR" crept into the Amateur
lexicon, or we became concerned about it, but I'm pretty sure I was rapidly
approaching "OT Status" when it happened.  Early on, we link coupled to the
final tank inductor and any reactance in the feedline just changed the
resonant point which was adjustable of course.  With the advent of the
ubiquitous pi-network, we were just matching the impedance presented by the
feedline to the plate impedance of the PA's [a couple of K ohms or so].

There is probably no single thing in a ham station more misunderstood [or
mis-named] than "The Antenna Tuner."

73,

Fred K6DGW
Sparks NV
Washoe County DM09dn