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Fitting a PL259 to a coaxial cable.

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Beginners Notes.

Fit to 10mm Coax or 6mm non reducer or Mini 8.
Fit to 6mm Coax using 10mm plug and reducer.

Quick and Dirty method (all types).


On another site:
In depth guide with photos by W8WWV.

Beginners notes:

The cable from your antenna will normally be a coaxial cable of which there are 2 common sizes, a thick one which is approximately 10 mm diameter and includes types RG 8/U and RG 213/U and a thin one which is approximately 6 mm diameter and includes type RG 58/U.

Fitting a plug to thin, 6mm, coaxial cable will require a PL-259 either made for the small diameter cable, or with an adapter (Type UG-175/V) or reducer to enable the smaller diameter cable to be secured into the larger plug.

Becoming more common is 'Mini-8' or RG 8/X coax which has a slightly larger diameter than RG 58/U and special PL 259s are available to fit this coax, fitting is as for 10mm and 6mm (non reducer) type.

10mm type pl2596mm type pl259Left is the 10mm type plug.

Note the larger cable entry hole than the 6mm type on the right.

Mini 8 type is simmilar to 6mm type, with a slightly larger cable entry hole.

reducers for 10mm type plug for 6mm cable use
Reducers for 10mm type plug for 6mm cable use.

If you have never soldered a plug to coaxial cable before it is recommended that you practice preparing the cable end using an extra piece of cable. Do not actually solder the plug on the practice cable.

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Step by step instructions for large size coaxial cable, 10mm:
Or 6mm (non reducer) type plug and mini-8, RG 8/X:

  1. Cut the coaxial cable (coax) to the required length.
  2. Unscrew the coupling ring from the plug and put it onto the coax with the threaded end nearest to the cut end of the cable. Note. The coupling ring must be put on the cable first as it cannot be fitted after the plug has been soldered to the cable. (I know, I've been 'caught' before!)
  3. Remove 28-30mm of the outer sheath which is likely to be made of black plastic. This can be done by cutting carefully around the sheath with a knife, taking care not to cut the shielding copper underneath.
  4. Using a small tip soldering iron and small diameter solder, carefully apply solder to the braid from the point where the sheath finishes for some 15 mm along the braid ensuring that you don't melt the dielectric.
  5. Now cut the soldered braid , but not the dielectric, with a fine saw or small tube or pipe cutter at 11 mm from the end of the sheath.
  6. At a point 2 mm. from the cut in the braid now cut through the dielectric but not the central conductor. Remove the cut piece of dielectric.
  7. Check that the coupling ring is still on the cable as instructed in step 2. (I usually slide it on then tie a loose knot to stop it sliding off). Prepare the plug by roughing the edges of the holes (A in the drawing below) slightly with sandpaper or similar.
  8. The cable is now ready to be fitted to the plug. Gently screw the plug on to the cable ensuring that all the central conductor is inside the hollow central pin of the plug. Continue to screw the plug on to the cable, the thread on the plug will grip the black outer sheath and then the soldered braid should be seen through the solder holes of the plug.
  9. With a soldering iron with a small bit apply solder in the holes and solder the braid to the plug. Be careful not to overheat the cable in the plug. (A very small tip will not hold enough heat, so make sure it is large enough for the job, typically a 30W iron will just about do it if the tip is large enough, but a higher wattage iron is best).
  10. Solder the central conductor where it protrudes from the central pin. Now cut off any wire protruding from the pin and remove any excess solder with sandpaper or a small file.
  11. Screw the coupling ring on to the plug and check that the assembled plug will screw into a socket. (untie the knot first, if used).
  12. If the far end of the cable is disconnected i.e. not yet connected to an antenna balun or a transceiver etc. then electrical tests can be performed on the cable.
  13. If practical check there is contact, i.e. a resistance of only a few ohms, between the central pin of the plug and the distant centre of the coax. Also between the outer coupling ring and the braid at the distant end of the cable.
  14. Provided there is nothing connected to the distant end of the coax check that there is a high resistance between the inner and outer connections to the cable. A resistance of 1M ohms or more can be expected. Note that if you are touching both the inner and outer conductors or both the metal parts of the meter probes, then you will be measuring your body resistance which could be only 200K ohms.

pl259 ready for soldering

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Step by step instructions for small size, 6mm coaxial cable using reducer/adaptor type of plug:

  1. Cut the coaxial cable (coax) to the required length.
  2. Push the cable through the centre of the adapter such that the narrow end of the adapter is nearest to the cable.
  3. Unscrew the coupling ring from the plug and put it onto the coax with the threaded end nearest to the cut end of the cable. Note. The coupling ring must be put on the cable first as it cannot be fitted after the plug has been soldered to the cable. (I know, I've been 'caught' before!)
  4. Remove 18 mm. of the outer sheath. This can be done by cutting carefully around the sheath with a knife ensuring not to cut the shield cable beneath it.
  5. Ensure that the end of the adapter is level with the outer sheath.
  6. Now cut the outer braid, but not the inner insulation, with a pair of small scissors at 10 mm from the end sheath. Remove the cut braid and fold the remaining braid back over the adapter. If necessary further trim the braid so that there is only 10mm folded over the adapter and it does not reach the tread.
  7. At a point 2 mm. from the braid now cut through the inner insulator but not the central conductor. Remove the cut piece of insulation.
  8. Apply solder to the central conductor.
  9. Check that the coupling ring is still on the cable as instructed in step 3. (I usually slide it on then tie a loose knot to stop it sliding off). and ensure that the braid is folded back over the adapter. Prepare the plug by roughing the edges of the holes (A in the drawing above) slightly with sandpaper or similar.
  10. The cable is ready for fitting the plug. Gently screw the plug on to the adapter ensuring that all the central conductor is inside the hollow central pin of the plug. Continue to screw the plug on to the adapter, then the braid should be seen through the solder holes of the plug.
  11. With a small soldering iron with a small bit apply solder in the holes and solder the braid to the plug. Be careful not to overheat the cable in the plug. (A very small tip will not hold enough heat, so make sure it is large enough for the job, typically a 30W iron will just about do it if the tip is large enough, but a higher wattage iron is best).
  12. Solder the central conductor where it protudes from the central pin. Now cut off any wire protuding from the pin and remove any excess solder.
  13. Screw the coupling ring on to the plug and check that the assembled plug will screw into a socket.
  14. If the far end of the cable is disconnected i.e. not yet connected to an antenna balun or a transceiver etc. then electrical tests can be performed on the cable.
  15. If practical check there is contact, i.e. a resistance of only a few ohms, between the central pin of the plug and the distant centre of the coax cable. Also between the outer coupling ring and the braid at the distant end of the cable.
  16. Check that there is a high resistance between the inner and outer connections to the cable. A resistance of 1M ohms or more can be expected. Note that if you are touching both the inner and outer conductors or both the metal parts of the meter probes, then you will be measuring your body resistance which could be only 200K ohms.

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PL259 Plug Fitting Instructions: Quick and Dirty method:

I've seen this done (and done it myself when a suitable soldering iron is not available) it can be done with 6mm & 10mm plugs (adaptor types fold the braid over the screw thread on the adaptor). It is NOT RECOMMENDED! as the shielding braid does not get soldered and, over time, corrosion can cause a resistance between the braid and the plug body which can result in a degradation of incoming signal and, possibly, damage to the transmitters output circuit due to high VSWR. Remember: Do It Properly and you only Do It Once!

  1. Cut back outer insulation by 30mm.
  2. Cut back braid leaving 6mm.
  3. Cut back centre core insulation leaving 10mm.
  4. Fold back remaining braid over the outside of the outer insulation.
  5. Twist centre wire so that no strands of wire are loose.
  6. Insert the cable into the plug and screw the braid into the threaded section at the rear of the plug.
  7. Solder the centre core wire at the tip and cut off excess.

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