[Amps] Power handling of an SMA

[Shane Youhouse]

The other (huge) thing not being mentioned is weatherproofing.

I have both weatherproof and non, and the diff in price between flavors is nil:  ie, REAL weatherproof PL259s are the same price as their N and BNC counterparts.

The PL\SO239 connector is SO MUCH MORE healthy, though.  I converted a 10 meter vertical to N connectors before I discovered weatherproofPL\SOs.  I get 3 inches of ice, and over 100 MPH winds here.  Weatherproofing is a BIG deal.

The N males failed 3 times in 1 winter.  The center socket wriggled around from having the gamma direct mounted and would hollow out.  The SO239 I'd replaced had been in 3 complete winters here, and was over 30 years old.  I put it back after the 3rd N failure, gorilla snotted the SO connector, and used gasketed PL259s since.  NO more problems since.

REAL teflon PL\SO connectors are 12 \ each single lot qty, and they differ very little, except in impedance match.


Transistors have ratings, tubes have guidelines!

--Shane  
Kilowatt Delta Six Victor Xray India

-----Original Message-----
From: Steve Thompson <g8gsq72 at gmail.com>
Sent: Tuesday, April 26, 2011 02:48 PM
To: amps at contesting.com
Subject: Re: [Amps] Power handling of an SMA

I suspect a lot of issues with 259s arise from the variation in 
materials. I see lots with nylon and brown 'plastic' (bakelite or 
SRBP?) insulation which I wouldn't trust under stress or with age. 
  Then there's the problem with the braid connection and the cold 
soldered joints onto low grade plating. Even when that's ok, the 
coupling ring is prone to working loose given time, mechanical 
movement or thermal cycling etc. Most other connectors have some 
form of spring fingering that maintains contact even when the 
coupling nut isn't tight.

Where the non constant impedance isn't an issue, a good quality 
well assembled 259 will handle a lot of juice - but it's a trap 
waiting for the unwary.

Steve

Carl wrote:
> A 30 Ohm connector that is 1" long will not even show a bump thru at 
> least 6M and they are still OK on 2M.
> 
> Some UHF articles have stated they are a perfect 50 Ohms at 1296, dont 
> know.I use them at low power on 2M FM gear including the 400W PP 4-125A 
> FM amp for contest into an old commercial 22' collinear.
> 
> Carl
> KM1H

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