Their is a great saying that ‘if it ain’t broke don’t fix it’, I was reading about the optimal (link to random length article) length of antenna wire, my overall wire length is 30m rather than at one of the optimum lengths specified in the link, one of the indicators apparently was if the auto-tuner tuned to perfectly, then it is not optimized for all the bands that the tuner can tune to.

According to the article, my antenna length should be 25.6m, so I loped 4.4m off the end and gleefully went to the shack to see what a dramatic change this will have made, well it used to tune on 80m and now it doesn’t 🙁

The ladder came back out as did the soldering iron and heat shrink, I now have it back to as it was and I won’t make that mistake again!

The table shows the results of the SG-237 tuning a 30m inverted ‘L’ wire at 6m above ground:

Lesson learned or is it now Lesson identified.

This is the final part in the installation journal, the first bit was to mount the end bracket which secures and terminates the antenna wire to the side gable at the front of the house, I used the ‘T’ from a galvanized TK type bracket, the one used was 24″ in length and secured to the masonry by 2 x 10mm expanding shield anchors.

To fit the insulator to the ‘T’ bracket I bent a small length of M6 threaded stud bar round a scaffold pole, to enable the insulator to slide of the exposed threads of the stud, I slid the braid from a length of coax over it and secured that with helleman sleeves at each end.

The existing TV pole and brackets were removed and the ‘T and K’ brackets were replaced, as were the securing fixings and pole brackets, this TV Pole also support the Weather Station anemometer and Direction sensor, so this was the reassembly order:

Nipped the pole up in the bracket and inserted the wind & direction sensor and pole into the top of TV pole and secured with machine screws, the pole was then pushed up slightly to allow me to add a log periodic TV aerial, the reason for replacing the existing TV aerial was to reduce windage loading on the pole.

The cables for the sensor and TV aerial drop within the pole exiting at the bottom before using conduit to pass through the wall.

Below the aerial is a bracket which secures a small length of pole at 90 degrees to the main pole, this has pulley’s which enable me to lower the insulator for maintenance.

The pulley parachord is secured with a halyard:

Couple of pictures which show different views of the antenna wire up:

The mod to this arrangement will be to replace the parachord with Dacron cord as I believe this is a more robust cord against the elements including UV.

Planning permission was granted today (10 Sept 2014 –  Ref:N9ZIWLHE01U00 ) for the installation of the 6m pole and longwire, in preparation I had mounted the 100mm x 100mm post and drilled the holes ready for the fixing saddles, this is a photo journal of the antenna install, this will be updated as each part is added.

Saddle secured to post using 10mm stainless steel stud, on the reverse of the post is an additional saddle to spread the load on the studs and to prevent any ‘pull-through’.

Pole secured to post using two saddles at 600mm centers, pole raised to insulate it from ground.

Paracord threaded down the inside of the pole and secured, this allows the insulator to be lowered for maintenance, the slack is pushed up inside the pole.

Tension on the wire is applied by the shock cord fixed to a hook, to reduce friction wear on the cord it is threaded through a galvanized pulley.

Side view of the pulley arrangement showing the shock cord fixing at the insulator and the clamp used to loop the flexiweave antenna wire.

View of completed antenna post, eventually the bush will grow to ‘soften’ the post.

Post up and antenna wire ready for high level fixings.

Click for part 4

Decided to make a dummy load as per the design of Ham AI4JI and incorporating ideas from a YouTube upload.

Link to AI4JI web site, this includes how to make the unit and also all the documentation showing how to take and interpret measurements in order to determine power output.

This YouTube video shows how to make a similar dummy load, the bit I took from this was the use of copper pipe.

https://www.youtube.com/watch?v=Gn0HaZMYzro

This is how mine turned out:

Parts & Cost

Ebay for the following –

1 litre Empty Paint Mixing Tin £3.75
2 x 500ml White Mineral Oil £15.50
BAV21 250v Diodes (pack 10) £2.67 inc P&P
20 x 3w 1k 500v Metal Oxide Resistors £5.70

Radio Rally –

1 x SO239 Socket – Chassis Mount – Nut Fixing £1.00

Shack –

1 x 0.01uf 2kV Ceramic Capacitor
200mm offcut of 28mm Copper Pipe
Red & Black Terminal Posts

Total Cost – £28.62

The Mineral Oil was the most expensive part of this build, I could have used engine oil as the coolant but taking the overall costs into consideration, under £30 for a 300w capable Dummy Load is not too bad.

NOTE– 12 October 14 – Even through I sealed around the terminal posts and antenna outlet socket on the lid, I have found that the mineral oil is so viscous that it ‘wicks’ up the wires and finds the smallest escape, even when not in use.
At first I thought I must have overfilled the can somehow, but their is a 10mm gap between the top of the lid and the liquid level, so capillary action must be the cause just to let you know.