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As I live in a small, old house in a conservation area, I am rather restricted with regard to antenna's, in order to operate on the hf bands I have overcome this in two ways, first, with my simple end fed antenna, and secondly, inspired by Will/GM0HKS I have made a Mag Loop antenna based around a wonderful vacuum variable capacitor which has winged its way from a Russian military maintenance depot via the Ukraine by way of ebay!!!

It cost only £22 with £10 delivery and was duly delivered recorded delivery 6 days later, not bad from the Ukraine.

I purchased 2 - 3 meter lengths of 15mm copper water pipe ----- problem number one, how to bend the pipe. I made a former out of MDF, which is simply a small piece filed in an arc and screwed to a larger piece of MDF - as in the illustration above. I also made an arc with a pencil and some string, to represent the final circumference. With nothing more than my thumbs and stomach muscles, a bending spring is not necessary, I managed to get the two pieces into a circle - not perfect but near enough.

Now I have the copper bent I have to think of some way to support the loop. I came up with the idea of using white plastic drain pipe and fittings. As can be seen by the photo I used a 90 degree bend to support the copper loop. At the bottom end I simply made a support using old wood and another price of plastic pipe which was conveniently a little larger to enable the support to "plug in".

The capacitor is attached to the stand using 2 brackets cut from discarded copper pipe, a small piece of wood and 2 nylon bolts liberated from a toilet seat!!!!
As you can see by this picture, the capacitor is connected to the main loop by once again using off-cut copper pipe cut vertically and opened up. Yes, the copper can be cut with nothing more than a cheap pair of scissors.

The Gamma Match is made from 1/8" copper tube (this is used by fridge engineers) connected by small copper brackets. These brackets (as with the top ones) can be moved to enable adjustment and if necessary soldered at a later date.The cable is connected to a PL239 socket.

The finished loop (with my car to give an idea of scale). Tuning of the loop is done with a piece of wooden dowel and so far it seems to tune easily to the intended 40 meter band.

100 pica farad vacuum variable capacitor
Diameter - 59 inches (circumference 15.5 feet approx)
Gamma loop - 37.2 inches
Made from 15mm copper water pipe (2 - 3 meter lengths - Focus DIY) and 1/8th inch copper pipe (donated by my colleagues at work)
The wood and plastic drain pipe, rescued from skips.


Ok, Loop performed well on 40 meters and above but in order to tune to 80 meters an additional capacitor is required. A 400 pica farad vacuum variable is horrendously expensive so I have made a simple home brew affair to "piggy back" the vacuum variable

The vacuum variable is now a trimmer - works great!!

As I am now looking to portable operation I need to disassemble the loop to fit into my new (old) Micra. First of all the yorkshire fitting at the bottom was removed and replaced by a simple compression joint (£2-30-Plumb Center). Now the gamma match, two problems, first it will not give me a 1 to 1 on all bands and secondly it is too delicate (the solder joint on the PL239 socket is vulnerable). I have experimented with a transformer match but it will only work on the design frequency. I have also made a couple of faraday loops but they also will only work on the design frequency. Solution, an adjustable gamma match.....

The coax is secured to a plastic bracket, center to the match and braid to the loop, the bracket at the other end can move up and down as it is secured by only two wing nuts.

With this moveable match a 1 to 1 can be achieved on 80m to 20m

Don't forget, 15mm copper pipe can be bent with only your hands, the pipe can be cut with sissors to provide brackets and capacitors can be home made.

Health and safety ----- high voltages can, sorry, will occur around the capacitor!!!

Hope to qso soon HF CW ---------73
Dennis MØMMX