Adapting PL-259 Coax Connectors to CATV Hard Line Coax Cable


Aluminum jacketed CATV hard line is an excellent feed line for amateur radio use.  Designed for transmission of TV signals in the hundreds of MHz range, it is very low loss at HF and VHF use.  It is mass produced for the cable TV industry so the cost is low. Since the cable installers don’t want to mess with lengths under a couple of hundred feet, these “short” pieces are often available for free or very low cost.

The problem is that connectors are expensive and often difficult to obtain. Even if the coax is free, the system cost can be very high if new connectors are purchased.

A number of methods of making connectors have appeared on the Internet or in magazine articles. I have not been happy with the complexity and/or cost of using these methods. Several years ago I came across a simple and reliable method on W5UN’s web site. Unfortunately that page does not appear to be online any more.

The basic idea is to use brass tubing to adapt the common PL-259 to the hard line. The first step is to get some 9/16” and 17/32” diameter brass tubing. This is available at hardware and hobby stores. The smaller tubing telescopes into the larger.  

Step 1. Use a tubing cutter to cut a .3” length of 17/32 diameter tubing and a 1.25” of the 9/16”.  Slip the 17/32” piece over the end of the PL-259. Solder it in place. Be sure the outer barrel is on the main body of the PL-259 as you won’t be able to put it on after the tubing is soldered on.  Use care not to get any solder on the outside of the brass tubing or you won’t be able to slide the larger tubing over it in the next step.

Step 2. Slide the 9/16 tubing over the 17/32 tubing.  Solder that to the smaller brass ring.


Step 3. Use a hack saw or Dremel tool to cut slots into the end of the 9/16 tubing.


Step 4. Prepare the coax by removing 1.75” of the outer shield. Then remove .75” of the center foam insulation to expose the inner conductor.

Step 5. Slide the modified coax connector over the hard line.  Solder the inner conductor and put a small hose clamp over the slotted brass tubing.  Weather proof with electrical tape.

Some types of hard line don’t use a foam insulator, but rather have plastic discs every few inches to hold the center conductor in place. This type has a center conductor that is too large to fit into the center pin of a PL-259.  You can’t just file it down because the conductor is copper clad aluminum. You won’t be able to solder to the aluminum.

Instead, cut a slot down the center of the conductor with a Dremel tool or hack saw.  This is difficult so take your time. Then use a pliers to press the two halves together and it will fit into the PL-259 pin. Since the copper is still on the remaining conductor, soldering is not a problem.

Surplus or scrap CATV hardline coax cable can be used as an inexpensive low loss feed line for amateur radio use.  It is easy to adapt standard PL-259 coax connectors with a couple of pieces of brass tubing. 

© 2009 - 2022 Gary C. Sutcliffe


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