Greyline DX Feedline Kit: Ladder-line to Coax PL-259 Adapter

Greyline DX Feed line Kit: Ladder-line to Coax PL-259 Adapter (options)

The Greyline DX Feedline Kit is meant to allow the installation of our antennas to be simply, 'plug n play' even when you see ladder line in the box, "what's that?" It's okay, we have you covered, it's all super easy no matter which of the several options you receive. Read on to see two presented below. Keep in mind, we reserve the right to create even better options without notice. (You're welcome!)

Some of you might receive one of several Feedline Kit versions, all of which are testing and approved by you and your friends...

Note: White chassis is a 1:1 Ladder-line to PL-259 Adapter by Palomar. (ca. 2018)

That's a ladder line to a coaxial converter that enables the ladder line into a coax connector making connecting your antenna to the remote tuner, plug n play, just like most of us prefer. (soldering iron not needed).

Some tuners have the balun posts or random wire posts on the back, which are needed to connect directly from the ladder line to the remote tuner, and most just do not have these, instead SO-239 for your Coaxial connector, which makes more sense, right? You will have the option of both, as you wish.

To be fair, purists, or guys smarter than most of us, count the number of junctions in the feed line system. These folks would tell us that fewer junctions are better, less lossy, and preserve dB's for your output and receive signal.

We combine the wisdom of these purists and make life easy for plug n play by offering you options that are less lossy and easy to figure out.

"Hey, we get it, every 1/2 dB counts! Just plug it in, friend."

In 2018, we chose to remove the more lossy coax stub here and replace it with Ladder line, or window line, in the feed line sections of the antenna system to take advantage of newly discovered performance (dB's), offering us all less loss and more DX. Even the high power guys can appreciate this one. Oh, and they do!

In order to make this simple for those less technically inclined, we developed (Thanks, W6NBC!) an adapter that allows the purists to choose ladder line and those of us QCAO (appliance operators club types!) to choose the universally acceptable, Coax connector. The purists appreciate fewer adapters, even though our adapter is very low loss and can take high power, too. Options are good, right?

If you want to get a head start, these parts are easily available online or you can receive one with your Feedline Kit included in your Greyline DX Flagpole Antenna order.

SPACERS: One note here on the Ladder Line Spacers... Inside the flagpole from the ground level to the feed-point, you'll want to install by hand the four included plastic spacers. These are 3D printed and work great to keep the ladder line centered within the Flagpole Antenna. Be sure to park the spacer in an open ladder area space about a foot apart as it travels in the flagpole tubing.

spacer, feed kit, 3d, greyline, flagpole, antenna, hf vertical, hoa, ham radio


450 Ohm Window Line to PL-259 Interface Block

Parts key:

- 3D Block Adapter Kit (block, bolts, nuts)
- PL-259
- UG-175 mini-8

Some users of the DX Flagpole antenna may be uncomfortable using hookup wire to connect the ends of the 450 Ohm window line (ladder-line) to the ceramic-insulator terminal and the grounding screw on the tuner. They may instead prefer to use the SO-259 coax output. Also, some tuners, such as the LDG RT-600 remote auto-tuner, do not have a ceramic output terminal. Remember, we do not ground the antenna system at all. (which includes the antenna, remote tuner, and RF Choke. Grounding your station, of course!)

It's true, ever hear of the QCAO club? Come on, you can do this! We've heard if you can't connect a PL-259 properly, you may lose your license upon inspector home visits. (okay, not really!)

This little easily-manufactured 3D-printed adapter block psychologically and conveniently overcomes this reluctance, by providing a sturdy direct interface between the 450 Ohm window line and the tuner’s SO-259 jack. See Figure 1.

Figure 1: PL-259 to 450 Ohm Window line interface.

Amazon Image: PL-259 and UG-175 mini-8

Figure 2 shows the interface shell with one of its two identical halves removed, exposing the wires and the insulation of the window line trimmed and soldered directly to a PL-259 solder-type connector and UG-175 mini-8 adapter. Also seen is a short length of 4 or 5mm Teflon tubing that replaces the polyethylene window line insulation.

The Teflon tubing enables the assembly to tolerate high power. Also for higher power, PL-259 connectors with Teflon insulation are preferable.

Image credit: YL Ham from W7

Figure 2: Assembly with half of the shell removed because of the shaped recess in the printed shell halves, seen at the left of Figure 3, the PL-259 and UG-175 adapter, when tightened create a very positive clamp to the shell. To the right, a raised portion in the printed block halves also very tightly clamps the window line.

Figure 3: A shell half showing recess for UG-175 adapter (left) plus a window-line compression box (right)

The holes in one shell half are drilled out to 9/64 in. as clearance for 6-32 screws. The holes in the other half are tapped for 6-32 threads. Four ½ inch pan-head stainless screws clamp the shell halves together.

Note: if weatherproofing is desired, the shell may be filled with RTV silicone adhesive during assembly.


Figure 4 shows the prepared ends of the window line, with dimensions. Lightly solder-tin to the wire tips.

Figure 4: Window line trimming dimensions. Note 5 mm Teflon tubing replacing the window line insulation.

The insulation on one side is completely removed and replaced with 2¼ inches of 4-5mm Teflon tubing. You can purchase 5-feet from Amazon for $5-10, for example. The tubing reaches up all the way into the PL-259 connector and permits the interface to operate at full power.

To facilitate easy soldering of the other wire to the UG-175 adapter, a 1/16 inch hole must be carefully drilled lengthwise at the edge of the adapter’s end boss. File a small flat spot on the boss edge for an accurate center punch for drilling. If possible, do not drill completely through the adapter boss.

Insert the longer window-line wire with the Teflon tubing installed into the UG-175 adapter. Then carefully solder the shorter window-line wire into the small hole in the adapter boss. File off any excess solder. Insert the Teflon-covered wire and the UG-175 adapter into the PL-259 connector. Screw in the adapter only a turn or two. The center wire should stick out of the PL-259 connector pin just a little. Do not solder it yet.

Next place the assembly in one half of the shell. Further, screw together the PL-259 connector and the UG-175 adapter until they clamp the edge of the shell. Adjust the bend of the wires in the shell for a good fit. Then install the other half of the shell. You may fill the shell with an RTV silicone sealant at this time if you desire. A sealant is, however, not essential and may be omitted if the block ever needs to be disassembled.

Next grasp the back end of the PL-259 connector with pliers and snug it up against the shell. Finally solder the PL-259 tip, trimming the center wire if required.

Depending on where the tuner is mounted, the interface block may be screwed onto the tuner either straight on turned 90 degrees to allow the window line to be led away appropriately.

Whether you are a coax plug n play operator or enjoy a little (easy) technical adventure that a 3rd grader can master in minutes, you have options!

Ham Radio is fun again!

73 Greyline Performance

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