[TowerTalk] Homage to Ohmage

[KD7JYK DM09]

>> Exactly, its off by 2 ohms!  Supposed to be 50.  LOL!

When we had standards, it was 52.  Once standard became "nominal", it 
was rounded down in print to cover sloppiness/ease in manufacturing.

Kinda like "4 full Watts!" seen in so many radio ads of decades past.
Shoot, I was really hoping for four partially filled Watts...

Interestingly, many things labeled 50 nowadays measure right around 52. 
  51.7 is pretty common, even with some MFJ loads, and my higher end 
items right around 51.97.  I figure the 0.03 is because my meter is off. 
  I guess "50" looks better in marketing.  The new "1950 Kluge Rambler!" 
rolls off the tongue better than, the "Improved 1951.97 Junque Velocipede!"

Coax-wise, I just use whatever I have from ~25-~75, the radios don't 
mind the lumped sum of coax and antenna ranging from ~37-~62 Ohms at the 
output.

Doing a quick test on the bench, I measured, on a 52 Ohm load (through a 
bunch of junk, see below), 1.15:1 at 52 Ohms, 1.20:1 at 37 Ohms, and 
1.35:1 at 62 Ohms.  The difference seen by the equipment across the 
loads varying by 0.05-0.20, or, 1.05:1, to 1.2:1, with "perfect" at 
relative 1.15.

For those that agonize over SWR, and interconnects, the baseline was 
determined with a source, transitioning through an SO-239, PL-259, 
BNC-Male, banana sockets, two cruddy 30 to 35-year-old 18" test leads 
twisted at ~2 turns per inch average, to two more banana sockets, to a 
plastic box with some resistors in it amidst a pile of junk on bench. 
All that only changed the relative SWR by .15, so the kluge was pretty 
clean.  The secret being- Find what works.  Don't mess with it.

A sealed 50.4Ohm load right at the source resulted in a reading 1:1 at 
the test frequency of 1680kHz (that's where all the junk was happy).

In the end, however, none of that has to do with "getting out", or 
efficiency of a radiator, so as awesomely flat-ish as 1.05:1 is, the 
antenna, in this case, a resistor, can be total rubbish, and blow 
everything to heck.

On the other hand, when the bands are in, trash works.  I used to tune 
up receivers mid-HF, mid-afternoon, with my finger on the antenna 
terminal, in my pre- test/alignment equipment days, for best reception, 
at worst conditions.  It's all relative.  That's the nice thing about 
radio, when it works, it's good, sometimes, it's better, and best is 
debatable.

Kurt