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Re: [TowerTalk] Coax

To: "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] Coax
From: "Jim Brown" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Tue, 13 Apr 2010 15:18:11 -0700
List-post: <">>
On Tue, 13 Apr 2010 17:26:12 -0400, Roger (K8RI) wrote:

>UHF connectors on HF have so little loss you'd never know they are 

Yup. I recently made up 1100 ft of very low loss RG8 in 100 ft lengths 
for the Iraq DXpedition. I measured their loss in series up to 500 MHz. 
That's 22 PL259s and 10 barrels. All real Amphenols, properly soldered, 
and real Amphenol barrels, not junk connectors. The loss at 500 MHz was 
slightly LESS than the mfr's spec for that length of cable at 500 MHz.

The potential issue with PL259s is a MINOR impedance discontinuity that 
can cause a SMALL reflection at HIGH UHF. Think about it -- what's the 
wavelength at 1 GHz? How long is the connector?  

Martin said:

"I take my information  from many articles that I have read"

Like I said, actual measurements, not folklore. I'd bet that those 
articles are repeating articles that their authors have read. The 
historian and journalist Gene Lees wrote a long essay debunking the 
false story in a newspaper saying that Dizzy Gillespie had a drinking 
problem. Lees had known Gillespie and many of his friends for decades, 
and knew that he had always been a teetotaler, but this single newspaper 
story was picked up and quoted, and those quotes quoted, and that sloppy 
journalism became accepted as fact. 

Your time would be far better spent studying the fundamentals of how 
transmission lines work in the ARRL Handbook or Antenna Book. And we 
would all be better off if folks would not quote folklore as fact. 


Jim Brown K9YC


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