[HCARC] "N" Connectors

[Kerry Sandstrom]

Hi Gary,

I prefer the Amphenol PL-259 UHF connentors.  The particular ones I use are 
83-ISP, the ones Bill, W3XO, mentioned at the meeting last thursday.  They 
don't appear to be silver plated to me.  The silver plated ones I've seen 
just have the end of the center conductor plated.  The UHF connectors to 
avoid are the ones that are cast.  you can see the parting lines on the 
coupling ring.  I don't have any idea what they are made of, but they aren't 
very rugged.  They also don't have the manufacturer's name on them.  If you 
see inexpensive  (~$1) connectors - avoid them!  I also avoid the ones with 
white plastic insulators.  The insulation melts.  I'm not sure how to 
relably identify Teflon insulated connectors so If I can't find the 
manufacturer's name, I don't buy them.  By the way, if I'm having trouble 
finding UHF connectors, I've been known to buy old cable with good 
connectgors on them and reuse the connectors.  After all, that is what ham 
radio is all about!

I use UG-21/U Type N straight plugs.  I've also used UG-23B/U.  Both types 
are used for RG-8, 9, 213, and 214.  They are solder type connectors and are 
weatherproof and 50 Ohm impedance.  The only soldering required is to solder 
the center conductor to the coax.  The shield doesn't require soldering.  I 
prefer the solder type because I am usually able to re-use them and as I 
have bought them all surplus, they are the ones usually available. 
Incidently, those cables are all 1/2" 50 Ohm cable.  RG-8/U has single bare 
copper braid, RG-213/U has double bare copper braid, RG-9/U has silvered 
center conductor and double silvered copper braid and RG-214 is the new 
designation for RG-9/U.

The tricky part of all the better RF connectors is stripping the coax to the 
correct dimensions.  The ARRL handbook has diagrams showing how to strip the 
coax and assemble the connectors.  It really isn't difficult.  These 
diagrams are in the "Component Data" section of the handbook which also 
includes a list of the mil designations for the various connector series, a 
list of the more common inter-series adapters, and the coax cables that can 
be used with each connector.  It is really quite useful and you will be 
amazed how many different connector series there are.

If I were using coax that has an aluminum foil shield, I think I would use 
crimp-on style connectors.  As I said previously, for foam dielectric coax, 
the center conductor is substantially larger in diameter than either the 
solid PE or teflon coax center conductors.  The standard connectors do not 
fit these cables.  If you're not using standard coax, you need to find out 
from the manufacturer which connector is recommended for his particular 
cable.  In any case, Amphenol is a good source of N-connectors.  There are 
several others.  I've found if the connector carries a mil designation like 
UG-21/U it will work OK no matter who made them.  There is anew mil 
designation for the connectors.  I think it is also Mil C17-XXXXXXXXX.  I 
haven't seen any surplus connectors labeled as such yet, but I have seen 
cables with the new numbers.

Amphenol also made/makes a line of N-connectors for IEEE 802.3 Ethernet 
LAN's.  Avoid them!  They are 70 Ohm impedance connectors and I don't think 
are as rugged as the UG-21/U connectors.  Amphenol also made/makes an RFX 
series of N-connectors which I believe are less expensive than the mil type. 
I haven't used them, but they should be all right if you are buying new 
rather than surplus.  By the way, the mil number for 70 Ohm N-Plugs is 
UG-94A/U, also avoid them unless you have 70 Ohm coax.

Probably more than you wanted to know, as usual.

Have fun,

Kerry