[TowerTalk] Junk Connectors (was Re: How lossy are PL-259s at HF?)

[john at kk9a.com]

Actually your 39.37 meter to inches figure is the approximation.  It's
closer to 39.3700787402.   1 inch = 0.0254 meters is exact.

John KK9A



Richard Karlquist N6RK wrote:

I have had a pet theory about off shore threads, may or may not be
valid: 

If a manufacturer in Asia has screw machines calibrated in metric
threads, 

there is a double dilemma:  metric threads are given in mm per thread 

while imperial threads are given in threads per inch.  Thus there is a  

reciprocal relationship in addition to the factor of 2.54.  Along with
this, 

there is the problem that any errors accumulate and get worse with more 

turns of engagement.   Also, the factor of 2.54 mm/inch is only an 

approximation.  The official conversion is that there are exactly 39.37 

inches in a meter.  This translates to 2.540005 mm/inch.  I don't know 

if that is part of the problem. 

I could quite possibly imagine a case where Chinese SO-239 threads fit 

Chinese PL-259 threads perfectly if they were made on the same screw 

machine, but would not mate with Amphenol parts. 

---
Rick Karlquist
N6RK