Building instructions End Fed kit

Preparing the Case

We start by turning the housing into the correct position so that there is enough space for the PL socket connector and, if necessary, the valve. This will also be important later if you want to mount a mounting plate for the toroidal cores or a valve. The housing should be aligned as shown in the picture. On the short inner side, there are 2 threaded bushings on the left and right for the mounting plate. The PL socket, the optional valve and the ring are mounted on the longer inner side.

Now we start to mark and drill the holes to be able to attach the antenna connector, as well as the feed points ANT and GND, and the ring. You can mark this directly on the case or you can use some masking tape. With this, the drill does not slip on the smooth housing.

The holes of the GND and ANT connections are drilled on the short side, the PL flange socket and the ring for the strain relief, on the long side of the case. The places where the holes should be drilled, are shown here on the drawing:

The two drill holes for the radiator and ground connection should be drilled with a 5 mm drill bit. The drill hole for the PL socket with 16mm and succeeds most simply with a step drill. The ring for the strain relief needs a 6mm hole. I pre-drilled the holes with a small drill bit. This facilitates the centering of the large drill and the drill holes also come where they should actually go.

On the underside, we drill the 16mm hole for the PL flange socket in the center using a ‘sheet step drill’. On the top side, we also center drill the 6mm hole for the ring. After all necessary holes are drilled, we should check if everything fits.

Now we take super glue and spread some glue to the back of the PL flange socket.

We put the PL-socket into the hole and align the socket. When the glue is dry, you can now simply drill through the two holes of the flange with a 3,2mm drill bit.

The ring for strain relief you now put on top, from the outside through the 6mm drill hole and put from the inside the serrated lock washer on it and tighten the whole thing with the M6 nut from the inside.

The impedance transformer

We are going to start on the impedance transformer.

For the winding of the ferrite ring, just follow the video:

End Fed 1:64 10-160m

For the End Fed 0654 with 1:64 winding and 2 toroidal cores, it has 7 and 7 windings instead of 5 and 7 like the 1:49.

It should now look like this:

Now shorten the wires slightly and remove the insulation layer of the enameled wire at the ends by about 1 cm with a „sharp“ knife or cutter. With a multimeter you should now check the continuity before soldering the cable lugs.

Remove plastic insulation (blue or red) from the cable shoe with a plier and solder the shoes to the ANT as well as the GND side.

Mounting plate

If you have a mounting plate, it is now time to tighten the transformer to it with cable ties and mount it in the case with the 4 screws.

Mount ANT and GND connectors

The next step is to mount the two 5mm screws for GND and ANT. Take one of the two M5 screws and put a serrated lock washer over it. Now thread the screw through one of the two soldered cable lugs and through the 5mm drill hole provided. Left GND, right ANT, as shown in the drawing. Now screw the collar nut onto it and tighten it. Do the same on the opposite side.

Finishing

Now connect the primary side of the transformer to the BNC housing part as shown in the picture below. Again, remove about 1.5cm of insulation from the enameled copper wire. Be sure to do this carefully so that a good solder connection is made. Due to the limited space inside the case this part of the Mini Endfed, this is the most difficult part. Bend and cut everything before assembling. Now solder the primary side first including the capacitor as shown in the picture below.

After this precision work, you can connect the secondary part of the transformer to the antenna connector. To do this, you can use the enclosed serrated spring washers and place them under and over the M5 cable lugs (i.e. they are inside the housing and not on the outside). Thisensures that the bolt will not rotate when connecting to the antenna wire.

Ready

You can test the End Fed antenna impedance transformer by applying a resistor of about 2500 ohms (e.g. 2K3) to the ground of the coaxial connector and the antenna connection. In this way, the SWR meter should indicate a standing wave ratio of about 1:1.5 or less. Of course, it is also possible to test with half a wavelength of wire.

Extension coil

Included in the package was a coiled and measured extension coil of approximately 34uH, 110uH or 192uH.

Continue by drilling two small holes, right next to the coil, where you can stick the ends of the wire in.

The next step is to drill two more holes as shown in the photo above. These holes will be used to put the wire through, which will be used as the strain relief. Finish this step by tying a knot in the wire and pulling it tight.

The excess wire can be cut off from the winding wire and the antenna wire. Leave just enough so there will be enough material for soldering. Make sure that the winding wire is completely stripped of the enamel layer. This can easily be done with a sharp knife or some sandpaper. Now solder the wire to the coil and put this into the pipe.

Now attach the heat shrink tubing and heat it SLOWLY and evenly until it is well seated. But CAUTION! The melting point of the shrink tubing is about 125 degrees. However, the copper wire also heats up a lot and retains heat! The PVC pipe becomes soft and deforms. Therefore, take your time with it and let the coil cool down from time to time.

Wire lenghts

For the 10, 20 and 40 meter band, with 34uH extension coil

10, (15), 20 and 40 meters tape without extension coil
20,35Meter +5 to 10cm usually work very well

For the 10, (15), 20, 40 and 80 meter band, with 110uH extension coil

For the 10-12-15-17-20-(30*)-40-80-160 meter band, with 192uH extension coil and 1:64 winding.

Fine tuning

The lengths shown in the graphics are approximate values! The ideal length always depends on the environment. So hang the Mini EndFed antenna with some additional length to the desired location. Always start tuning by sizing the antenna wire for the high frequencies. This is the piece of antenna wire that sits between the impedance transformer and the extension coil. Always remember: don’t cut too much! It is usually a matter of centimeters and not meters! You can also use a wire clamp to fold the stranded wire over first before cutting! When the higher tapes have an acceptable SWR on average, you can start sizing the piece of wire beyond the coil.