Some examples of the Squid Pole interface box built by NERC members

Click on each photo to see a larger image.

This first image is of the prototype and this version has been built by most club members. Band selection is done by jumper leads with 4mm plugs and sockets.

These three images are of the version built by Trevor, VK5ATQ. In this version Trevor has used a three pole switch to select the 80, and 20 Metre coils or straight through for 40 Metre

These images are of the two versions built by Phil, VK5SRP. Phil has also used a three pole switch. Details on how to build these at the end of this page.

Early in September 2015 Les (VK5KLD) came to me for some technical help. He had started building the Squid Pole interface at the NERC technical night but it had turned into a UFO, an unfinished object. I took this on as an oppertunity to make another easier to build version with a three position switch and using a readily available Jiffy Box. Rummaging in my box of boxes I found an AZtronics/Altronics H0151 158X95X53 mm grey plastic box, ideal for this new try at the project.

The two coils are mounted with 25mm PK screws driven into small holes drilled 60mm apart on one side of the coils. The Beehive trimmer is accessed through a hole in one end of the box. Two poles of the three position switch are used, one pole switches the antenna wire from the 80M coil, straight through for 40M and to the 20M coil. The other pole switches the input from the coax connector to the coils and straight througn in the 40M position.

Building the VK5SRP version of the Squid Pole Interface

Parts list

Proceedure - The radiating wire and the loading coil

The resulting length of wire + coil is used as the radiating element on all bands.
This length of radiating wire with the loading coil is now ready for use on the 40, 30 and 15M bands without the interface coils. The rotary switch will connect the coax socket from your rig to the bannana socket you plug the end of this wire into. No other coils required for these frequencies.

Next we build the 80 and 20m coils

The 80 Metre coil: Primary 25 turns of enamelled copper wire, Secondary 5 turns of hookup wire

The 20m coil: Primary 10 turns enamelled copper wire, secondary 2 turns of hookup wire

Tuning the 20M coil

Tune the 25pF trimmer for maximum received signal strength at 14.2MHz. Fine tune it by adjusting it for minimum SWR at low power output on the same frequency. If the tuned circuit is working properly there will be a single very obvious spot where RX and TX work brilliantly. If you have an antenna analyser you can tune it perfectly and expect to achieve a nice 50 ohm non-reactive load.

Connecting to your ATU

For portable use it is highly desirable to position the ATU right at the bottom of the squid pole. That way there is no coax between the ATU and the squid pole and thus no RF coming back down the coax into the portable radio shack. Stray RF with a poor earth is usually overcome when the ATU is at the base of the antenna because that configuration provides properly matched coax running back into the vehicle or tent. The perfect solution is a remote ATU and if you are doing much portable work you should rush out and buy one now.

This version of the Squid Pole interface is based on an project by Phil (VK7JJ)
My edited version of the above web site in PDF
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Written by and Copyright, Phil. Storr © Last updated 8th September 2015