Fwd: Re: [TowerTalk] N connectors

[Jim Lux]

At 11:44 AM 9/9/2003 -0500, Jim Rhodes wrote:
>Ok, Strike #1 off of your list if you use these. They are no more weather 
>proof than a UHF connector.


Nonsense... N connectors have gaskets (if properly assembled) and are 
weatherproof.  For that matter, they pass hermeticity tests for vacuum 
chambers. We use them at work all the time as bulkhead feedthroughs into 
vacuum chambers. As to whether the cable to connector interface is 
weatherproof is more a matter of proper assembly.  Check out the datasheet 
on Amphenol's site.  That's not just idle puffery, it's a real spec, and 
gets tested exhaustively.

No gasket on UHF connectors... not to say that both types can't be 
assembled and field potted (i.e. wrapped with stuff) to make them weatherproof.


>Also, has anybody tested these to see what the impedance really is?

a - That's part of the spec, which says, < 0.15dB loss and VSWR<1.3 from 
0-11 GHz
b - In practice, they're a heck of a lot better, if not mistreated. I've 
measured them numerous times on a calibrated network analyzer.  They really 
are 50 ohms and flat to at least 14 GHz.  I've built high precision systems 
for which changes in loss of 0.01 dB can be detected and they use Type N 
connectors. (The mate/remate consistency of N connectors isn't all that 
hot.. You could expect a couple tenths of a dB change each time you mate 
them, at microwave frequencies, at least, unlike a precision connector such 
as a APC-7)

I note that the special versions made for corrugated coax (hardline) spec 
out at 33 dB return loss .. that's about 1.05 VSWR

But, as has been pointed out more times than not, the impedance problem 
with a UHF connector is probably insignificant at HF frequencies. (just how 
tightly controlled is the impedance of that coax, anyway.... Belden cites a 
typical spec of 4% for solid conductor and solid dielectric, and a VSWR for 
the run of the mill cable of 1.1:1 (due to manufacturing variability in 
dielectric, etc.)

I did a casual search for any actual measured impedance data for a UHF 
connector and couldn't find it.  Maybe I'll have to scrounge up a suitable 
network analyzer and try it someday at lunch time.



>Not that I haven't used them for jumpers in the shack. But I really 
>wouldn't consider them that much superior to a UHF connector except for 
>impedance (and like I said I wouldn't swear to that without confirmation).


Another advantage of N connectors is that they produce the specified 
performance when tightened finger tight (re: the discussion a week or so 
ago about using pliers on UHF connectors) and are available with safety 
wire holes to keep them fastened in the face of vibration and temperature 
cycling.


>At 02:03 AM 9/9/03, Dino Darling wrote:
>>I finally found a picture of the ANDROS N Connector....
>>http://www.universal-radio.com/catalog/parts/4505.html
>>
>>>Date: Mon, 08 Sep 2003 23:52:40 -0700
>>>To: towertalk at contesting.com
>>>From: Dino Darling <k6rix at arrl.net>
>>>Subject: Re: [TowerTalk] N connectors
>>>
>>>There sure is a lot of speculation out here when it comes to 
>>>N-Connectors!  Its almost embarrassing!
>>>
>>>N-Connectors are SUPERIOR to the UHF connector for many reasons...
>>>1- Weather proof
>>>2- Constant impedance to 11 Ghz
>>>3- Constant impedance.
>>>4- Able to withstand HIGHER voltages!  (1500 volts peak)
>>>http://www.amphenolrf.com/products/typen.asp