The first Antenna page

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More antenna projects on the "Projects 2015" page

My second tower is up in the air and it has four antenna on top

The Antenna Farm

The first photo below shows the 10 metre tower beside the shackwith the centre of the G5RV antenna and a 6 Metre J-Pole made from copper pipe. The next photo shows more details of the 6 Metre J-Pole. The third photo is of the 2 Metre RingO attached to the back gable of the house outside the radio shack. The last photo is of the Tet-Emtron TEV4 four band vertical mounted on an out building in the back yard. This antenna has eight tuned radials (two for each band) that are strung around from the antenna pole to various points in the yard.

Vertical antenna experiments

I have been experimenting with home built vertical antenna for some time and hoping to be able to get something working on 160M. My noise level on this band is S9 on a good night but perhaps I can come up with an antenna that will make the use of 1.843 MHz AM viable !. My frrst attempt was to find an old 27MHz CB Bandmaster and make it much longer with loading coils in the middle and on the bottom. I got it working at 2.3MHz quite easily by making it eight metre tall with a long 100uH loading coil in the middle. The next stage in this development will be to add a roller inductor tuned with a remote controlled stepper motor to the bottom. My knee operation October last year has stalled this project as I am not agile enough yet to get down and get dirty working on this antenna near the ground.

Recently I was given a MoonRaker W22 with an unloaded top section and I decided this would make an ideal field day antenna for setting up in the bush. The first experiment did not go too well and I blamed the Kenwood AT-230 I was using to tune it when it was connected to my still sick IC-701. I had decided to keep it for club use at field days out in the bush but this plan did not get off to a good start at the 2013 John Moyle Field day. I could not get a low SWR on 40 Metres, no matter what I did and I could not operate on other bands most of the time because 80 Metres did not work on my Icom IC-701 and other operators were using other bands on the same site.

When I got home from the Field Day I rummaged on the web for a second hand AATU and soon found an SGC SG-237 that was in my price range. Deciding it would be a waste to only use this setp for field days I made a wood quick release bracket seen in the photos below and mounted it on a verandah post. When I read the instructions for the SGC AATU I found they claimed it would tune down to 80M with 6.5 Metre of antenna and down to 160M with 8.5 Metre. The W22 is about 6.5 Metre long so I added some 10mm tube to the top and put it up to try it out.

All was well as I tested it on 160M and 80M, yes it gave a respectable SWR on 160M and it is only 8.5 Metre long. When I got to 40 Metre the SWR was about 5:1, just like I was seeing at the field day ! Tried it on the other bands up to 10M and it was fine, SWR never more than 1.35:1 through the SG-237. It was about then that I started to see what I had done wrong at the field day. Instead of cutting the single conductor lead wire from the antenna to the AATU I coiled it up with two cable ties. Cut the cable short and the SWR on 40M was then a health 1.3:1. I sure learnt a leason that day and now I can work 160M but this is hampered by an S9 plus noise figure on this band most of the time.

Slim Jim

At a North East Radio Club technical night quite a few of our members made a 2 Metre Slim Jim antenna out of 300 Ohm Television Ribbon. This stuff is now very hard to find but one of our members searched all the Dick Smith stores here in Adelaide when they were going out of any thing useful and bought all he could find. I had made one of these some time ago but was not satisfied with the job I had done on the feed area and so I made another one. This did not turn out too good either and then Bob (VK5AK) suggested why not simply just cut the cable and join it with two strips of tinned copper wire to which the feed coaxial cable can be soldered and adjusted for best match.

The next day I cut that section out of the Slim Jim I had made and modified it like you can see in the photos below. The white plastic is 1.6mm plastic sheet but any insulating material should be satisfactory. I then went on to make a 70cM version and one tuned to 126.5 MHz for a friend who flys around in a little plane and likes to be able to listen to the local air traffic from his home not far away from the local country airfield. I used the Slim Jim claculator from MUKD, the link is listed below.

I used a hole punch to cut the 3mm holes in the ribbon for the 3mm nylon bolts that fix the ribbon to the plastic strip.

A very poor low pass filter, rubbish found in the junk box

Found a low pass filter and thought I may use it in the HF Antenna circuits until I drilled the rivets out and had a look inside. Looks home made but it was Archer, the double sided tape used to make the capacitors is very crude. Make sure any second hand item you want to use is actually working. I was caught by another low pass filter, I was testing the TS-50 on my antenna switching circuit and found the TX was operating into a short circuit. I worked my way back to the dummy load from the TX and found the other filter, also out of my junk box, was shorted. Took it apart and found three ceramic capacitors blowen apart and shorted. It was about then I remembered the fellow I got this one from had a 500 Watt linear.

Selected pages from the Technical stuff on this web site
Introduction to the Squid Pole Antenna
The Balun and the UnUn
Intoduction to HF Radio Propagation - Australian Government IPS Radio and Space Services
Understanding LF and HF Propagation - free ebook from Steve Nichols (G0KYA)

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Written by and Copyright, Phil. Storr © Last updated 16th March 2016