[TowerTalk] 4.3-10 Connector for RG8

[Jeff DePolo]

> ##  why would hams want to use a Type N  for HF use??   

For starters, because it's constant-impedance (less of an issue on HF, but
definitely an issue on VHF and above), and is more weatherproof.

> Type N has the puny bnc sized center conductor.   

I'm not sure why you brought up BNC.  Yeah, you can jam a type N male onto a
BNC female in a pinch and hope that it stays put, but BNC male and type N
male do not have the same center pin diameter.

A type N connector's pin diameter and the design of the interface handles
legal-limit current up into UHF.  You can run 1500 watts through RG142B all
day and night on HF, and its center conductor has only about 1/3 of the
cross-section area of a type N center pin...and you're not going to fuse the
center conductor of either the cable or the connector.  The only times I've
had "burn outs" of a type N center pin, even at 1 kW+ in continuous-duty
broadcast use on AM or VHF FM, were either due to lightning or when the
connector/pin was not installed properly to begin with.  

My point was that for most gear on HF, and even more so on VHF and UHF, the
only reason that UHF still seems to be common is because "that's what hams
have always used", not because it is a superior connector.  If the ham radio
world were to standardize TODAY on one connector which would be suitable for
95% or more of the types of things hams do, and the types of equipment they
do it with, in their home and mobile stations, I would think type N would be
a logical choice, all things considered (power handling, ease of assembly,
cost, availability, reliability, weatherproofing, etc.), but personally I
wouldn't complain about the slightly larger size (or even slightly higher
cost) of 7-16 DIN...

> 1.625 heliax,  with a type N looks pretty silly  with that tiny bnc sized
pin.

I wasn't promoting using type N's on large-diameter cable.  Unless there is
a very good reason to do otherwise, I don't purposefully spec or design
anything that would result in type N's being used on any cable larger than
1/2".  Even though type N can handle a good bit of power, mechanically it
becomes the weak link when you're dealing with large-diameter cables.  7-16
DIN is much better in that regard, or EIA flanges even better especially for
higher-power situations and larger cable diameters.  

I can't tell you how many failures I've dealt with over the years with
someone attempted to repair or extended a Heliax run by using a pair of
mated type N connectors -- one of the two connectors ultimately ended up
breaking.  If you have no other choice but to join two large cables together
mid-run, use a flexible jumper (like 1/2") between the two larger cables
with a one-turn coil in it (and use 7-16 DIN connectors), or use flanges for
large-diameter cables or if a 7-16 DIN won't handle the power.

> ##  PIM is a non issue for ham gear.   

Not for repeaters.  But for single-carrier service as one would typically
find at a home station, it's not much of an issue.  Regardless, my point was
that I wouldn't expect any big surge in 4.3-10 connector popularity or
availability for non-PIM cables like RG-8 because there will likely never be
a commercial demand for them.

						--- Jeff WN3A






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