Re: [amsat-bb] N connectors-failures?

[Stan <stan@xxxxxxxxxxx>]

Hello Greg,

I have used a lot of N connectors, here is some guidance..

Use a quality connector, about  5$ each new is what I pay. More for 
specialty cables like ANDREW's LDF5-50A etc.

Avoid the 2 part N's above 222 MHz

Find the manufacturer's assembly instructions and adhere to them

Avoid interaction from dissimilar metals on the center pins and keep the 
center pins straight and centered.
Center the pin after soldering and before assembly

Check each N connector before you mate it. The male center pin should 
barely be felt with your finger tip.
Any more exposure will result in a greater likelihood of the female pin 
being damaged.

Observe the impedance of the connector. Do not mate different impedance 
connectors.
A 50 ohm male center pin is guaranteed to destroy a 75 ohm female pin.

I use N connectors at legal limit at 222 MHz and below.
I will probably use a 7/16-DIN connector for the legal limit 902 and 
1296 MHz amps...

Mate a connector only to the diameter cable it is designed for.

Wrench clamp connectors are just as good as crimped connectors when 
properly installed.
Adjustable wrenches are as common as dirt. Good crimping tools are scarce.

No connector is weatherproof. Always seal up all connectors applied 
 outside.
Scotch putty tape, then a double overlapping wrap of scotch 88 or 33.

I would avoid using  additives like a conductive grease because the 
impedance may change,
the voltage withstand rating may be degraded, the introduction of 
dissimilar metals may reduce
conductivity and  reliability.  A flammable base of the conductive 
lubricant may cause an
exposion and fire if the center pin heats up during a poor VSWR event.

If possible use captive center pins. Free floating center pins will move 
in and out with
thermal expansion and contraction as well as when the cable is bent in a 
tight radius.
Wind movement should not cause any significant center conductor movement 
problems

Get ready for the MArconi special event next week from FN51 in Eastham, MA
Look for me on the FM LEO's as KM1CC morning and  evening passes.

Stan, WA1ECF




Greg LaHaie wrote:

> An apparent intermittent antenna connection on my homebrew uplink 70 
> cm helical has me wondering if the female N connectors have a tendancy 
> for the junction of the pin/mating socket to fail (due to mechanical 
> stress from wind on the cable?)
>
> Anybody had experience with these junctions being problematic? I am 
> considering a miniscule amount of conductive grease into the socket 
> tip before mating the connectors and wondered if anybody has tried 
> this before?
>
> Thanks
> Greg
> K7YDL
>
>
>
>
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