Friday, January 15, 2016

Weekend Project - 30 meter Loop

Here's a nice little project which should only take about a day to complete. I found it while trawling the net a few weeks back. It's for a 30 meter loop antenna, very easy to build and so far seems to work well. I've got it strung across a couple of trees, unfortunately not very high about 20 feet but it works reasonable well and is a bit of fun for a weekend project. Have a go and see how you get on.

This antenna is an easy construction project.  It was made out of common number 12 stranded electrical wire.  The side and top attachment points are made by removing two inches of insulation and wrapping and soldiering in short lengths of wire to create small loops. Non-electrical rope should be used for the support line and side pull out lines.  The bottom insulator should be about 3 by 5 inches in size and trimming the antenna to resonance was done at the bottom.

Start with the formula of 1032/Mhz to determine the total length.  I ended up pruning about a foot off of each side to achieve resonance at 10.125Mhz.  I used 72 ohm RG59 for the matching section.  Make sure you take into account the velocity factor of the coax when cutting it to length.  One method is to place a 100 ohm resistor at the end and use an antenna analyser designed for 50 ohms to measure for zero reactance (and SWR) while trimming the section to the correct length.
At 10.125Mhz, the SWR is 1.1/2 : 1, R is good at 50 ohms  (When I got these results, I decided not to build a balun).

Within a couple of hours of putting up the antenna I had made five DX QSO's.  It has performed well ever since.  The antenna is not overly directional probably due to the wire sections all being 45 degrees with respect to ground.

Thursday, January 7, 2016

Sending CW with confidence and QRP Work With the OHR 100A

I'm still having some minor trouble with my CW sending in only that I have this fear of sending, it's all due to confidence from post stroke, I'm rectifying by deliberately sending a QSO everyday trying to gain confidence and thankfully it does seem to be working, although local chit chat on CW is rather monotonous!

It's similar to my speech which in all fairness you wouldn't really notice, but I'm a bit self conscious and know that I'm a bit quieter than normal. Hopefully I can gain some voice experience on Sideband, deliberately talking to all manner of Amateurs, eventually I'm sure I will lose the nerves!!

Radio wise its fairly quiet at the moment with just European stations popping up I haven't heard many US or Canadian or for that matter DX in general, I think its just fairly slack but occasionally you do hear the odd station from some distance.

So I'm mainly doing QRP work with local stuff using the Ft2000D on low power or the OHR 100A at 5 watts. This is a pretty neat QRP rig that the XYL bought a few years back as a prelude to me building the K2. I really like it, probably use it as much as the K2  because its so easy to set up and use. The receive capability is very good for such a small kit and the only pain is it tends to drift on warm up, but that is on for the first ten minutes and then it's fine for operating.

The  OHR 100A kit was fairly easy to build, the only practise I'd had beforehand in kit building were the Rock Mites, so I was really starting from a early building position and I found little problems with the OHR 100A.
It's set for 20 meters and does a good job and banging out CW at 14.060 I can guarantee in good conditions I'll get an answer with nice RST reports. If you are thinking of a 20 or 30 meter kit I'd certainly recommend the OHR 100A and its not that expensive either! The only pain when purchasing for UK buyers is it comes from the USA so you have to pay £30 import duty.
Here's the site:

The OHR 100A
The box on top is a home brew frequency counter, very useful.
Very easy to build and produce good results.