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Re: [TowerTalk] compression PL259

Subject: Re: [TowerTalk] compression PL259
From: Ian White GM3SEK <>
Reply-to: Ian White GM3SEK <>
Date: Fri, 21 Jan 2011 15:57:42 +0000
List-post: <">>
Craig Clark wrote:
>When Pete brought this up, I went off on a tangent thinking a PL259 had 
>been designed that was similar to the newer F connectors that are 
>called compression connectors. On the F, you strip it per 
>specifications and them compress the back of the connector to complete 
>the job. I was wrong.
>We refer to the connector as a "clamp" type to differentiate between 
>crimp and the Ham standard solder type PL259.
>One of the differences I see in looking at the RFI RFU-503 and the 
>European connectors is that on the RFU503 the ferrule that the braid 
>fits over has a beveled edge that mates with the gasket while the 
>European version has a flat edge. I'll leave it to an engineer to tell 
>us what is a better design.

The RFU-503 is -NOT- the type of connector that I was describing and 

I have tried the RFU-503 type and they are far inferior to 'European' 
design. The anchoring strength of the RFU-503 depends critically on the 
braid being trimmed to the correct length and combed out evenly all 
around the washer. Otherwise the cable will not be clamped tightly all 
around, and will easily tear loose.

The 'European' design has none of those problems. There is no jacket or 
braid trimming: cable prep is simply one flush cut going all the way 
through the jacket, braid and inner insulation. No special tools, no 
measuring, no fancy surgery at the top of the tower - one cut with a 
sharp knife and the cable is ready.

The ferrule in the 'European' design is shaped like a top hat, with a 
sleeve and a flange, as shown in this picture:

The sleeve of the ferrule slides onto the cable, between the braid and 
the inner insulation - no combing required (remember, the braid was cut 
flush with the jacket).

Then the clamping force comes from compressing a large rubber sleeve (as 
you can see from the picture, this sleeve is much larger than the small 
washer inside the RFU-503).  When the back nut is tightened, the jacket 
and braid are squeezed radially inward onto the sleeve part of the 
ferrule, while the flange part of the ferrule is forced into a solid 
360deg connection with the plug body.

It's simply a much cleverer design. Accept no substitutes. Salesman does 
not receive commission.


73 from Ian GM3SEK

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