[TowerTalk] N CONNECTORS

[Craig Clark]

There are several basic types of N connectors. There is the 5 piece 
clamp which requires you to solder the tip and then you clamp the 
braid,#1, a crimp, #2 and the two piece solder type which 
necessitates soldering the pin and the braid like you do with a PL259, #3.

In my experience, if you properly install the center pin on type 1 
and 2, proper pin installation, you should not have a problem with a 
lack of continuity in cold weather. I have spoken to friends in the 
cable industry and they have told me this happens from time to time 
in their lines and seems to be more prone with the solid center 
conductor cables like CATV and 9913 coax than the stranded coax.

The two piece N connectors are made domestically by Andros in 
Rochester NY and also imported from the Far East and are sold by a 
number of us in the business. You prep the cable the same way as you 
do for a PL259 and then thread the connector on the cable. Using a 
small sized solder, heat the tip and solder. Then solder the two 
holes as you would with a PL259.

What I have found when installing the two piece N connectors is that 
you have to be very careful aligning the center conductor with the 
pin. With 9913, the ID of the pin is almost the same size as the 
center conductor of the coax and if mis-aligned, you could 
conceivably push the center pin out of the body of the connector and 
I have had this happen with the Andros connectors. I have not had the 
same problem with the imports as it seems the ID of the center pin is 
a bit bigger.

Here is some more information taken from about UHF and N series connectors.

http://ece-www.colorado.edu/~kuester/Coax/connchart.htm

"The Type N 50 ohm connector was designed in the 1940s for military 
systems operating below 5 GHz. One resource identifies the origin of 
the name as meaning "Navy". Several other sources attribute it to Mr. 
Paul Neil, an RF engineer at Bell Labs. The Type N uses an internal 
gasket to seal out the environment, and is hand tightened. There is 
an air gap between center and outer conductor. In the 1960s, 
improvements pushed performance to 12 GHz and later, mode-free, to 18 
GHz. Hewlett Packard, Kings, Amphenol, and others offer some products 
with slotless type-N outer conductors for improved performance to 18 
GHz. Type-N connectors follow the military standard MIL-C-39012. Even 
the best specialized type-N connectors will begin to mode around 20 
GHz, producing unpredictable results if used at that frequency or 
higher. A 75 ohm version, with a reduced center pin is available and 
in wide use by the cable-TV industry. "

"The UHF type connector saw its conception in the early 1930's, a 
time when VHF/UHF technology was quite new. The forefathers of VHF 
were in many cases Amateur radio experimenters, most with Engineering 
and technical backgrounds. They began experimenting and working the 
VHF frontier around 1926. Soon thereafter research into FM radio and 
Television began and out of this era came the then named UHF 
connector. Manufactures of UHF plugs and receptors all state that 
this type connector are of generally non-constant (characteristic) 
impedance and are suitable for use up to 200 or 300 MHz only, 
depending on production quality. They also state that the UHF 
connector can be used up to 500 MHz with a cautionary note of reduced 
performance.

The so named UHF connector from the past is not really suitable for 
use above 300 MHz at all. Perhaps the exception to this would be when 
a cheap and rugged system is required where loss and good signal to 
noise ratio is of little concern. However, even for frequencies as 
low as 144 MHz, if low loss and good signal to noise ratio are very 
desirable, the use of UHF type connectors is not recommended. The UHF 
connector still has a place in many applications where a robust but 
economical RF connector is required, but for serious applications its 
use should be limited to below 100 Mhz. The N type is far superior in 
performance, and it should also be noted the BNC type connector is 
similar in performance to the N type, but has the disadvantage of 
being less rugged."


73, Craig Clark, K1QX


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