AmateurRadio.com

10m band loop

A magnetic loop can be a very effective HF antenna, especially when the very sharp tuning is not an issue. They can be very efficient but there is a trade between bandwidth and efficiency. They are ideal for modes that do not need frequent retuning such as PSK31, JT65 or WSPR. Ideally the inductor should be made of copper pipe or thick coax and the capacitors need to be low loss and high voltage types. Tuning is usually very sharp. Having said all this. quite decent results have been obtained with loops made of quite thin wire.

See https://sites.google.com/site/g3xbmqrp3/antennas/magloop .

A very successful antenna for VLF, LF and MF receive only is an E-field probe. Ideally these should be mounted outside the house with some experiments to find the quietest spot. Size is not important and these are much smaller than many antennas for much higher frequencies.  The picture shows an example EFP. This is the complete antenna – no wires or loops etc are needed in addition. They can be made by just about anyone, so there is nothing stopping you having fun on 136,472 or even VLF RX.   Some people have built these inside a short length of uPVC pipe. The important thing is they are very small and work well on the lower bands.

I have also used EFPs as mag mounts on the car when looking for my signal on 136kHz QRSS3. These are very compact antennas. PA0RDT has created a good design that many people are using.

See https://sites.google.com/site/g3xbmqrp3/antennas/efp .

I see Elecraft has launched a deluxe version of its K3 transceiver. The K3 was already a pretty good rig and the S version will be even better, but sadly far too expensive. I guess Elecraft is right that this will be many times less expensive than similarly spec’d transceivers, but to me this is still far too much for an amateur radio rig. Don’t forget that lots of the features cost more – like the mic and 2m!

At half the price maybe, but certainly out of the question here in the UK when shipping, import duty and VAT have to be added. I am able to get lots of fun from our hobby spending just a small fraction of the cost. There will always be people who will pay these prices and buy a tower and a big beam.  Sorry, but this is not for me. I wish Elecraft well but feel they will need to slash prices soon to compete with the Chinese. An alternative is for Elecraft kits to be shipped from China. Sorry, but this may be the only way they will be able to compete in the future.

See https://sites.google.com/site/g3xbmqrp3/hf/tenbox

This very simple 10m AM transceiver is based on the Fredbox and Sixbox transceivers. This is designed for local communications and NOT DX. Although the RX and TX have been breadboarded, illness has prevented the project being boxed. It would benefit from a 10dB TX linear and a RX LS amp such as an LM386 stage. More details on my main website.

See https://sites.google.com/site/g3xbmqrp3/hf/interval  .

For a touch of pure nostalgia try the link above. Like many, my first experience with short wave was as an SWL, listening on a simple receiver to some of these broadcasters. Many were trying to indoctrinate me whereas all I was really interested in was a QSL card! I recall some great gifts from China! I heard some impressive DX back in the 1960s.

Of course radio amateur DXing came later and  radio amateurs ran considerably less power. These days I regularly copy stations running less than 5W from the other side of the planet, but I can still recall the thrill of hearing a 5kW broadcaster in the Windward Islands and copying Radio Australia on a crystal set – all the way from Australia too!

As you will have noticed by now, 10m is one of my favourite bands.  Although quiet at many times in the solar cycle it always comes to life with Es from late April until September. Alert 10m operators will sniff out Es at other times too, but there may be long periods of noise, as on 6m. WSPR is an ideal mode when the band may otherwise seem quiet.  It is good for local nattering at any time and F2 N-S DX  is often there even at solar minima.  Antennas for the band are small and easy to make such as the design on my website for a 10m halo. See https://sites.google.com/site/g3xbmqrp3/ .

A video of K7AGE making a dipole for 10m is available at YouTube.  See https://youtu.be/84F4UgSWmQo.   In this video, Randy is making a dipole for the USA technician’s band, so to cover the main SSB band (28.4 to 28.6MHz) you will need to make the wire slightly shorter.  In my experience if you cut the wires for the centre of the band it will still have a pretty low SWR at the band edges. Even a very simple ATU will bring the SWR down to 1:1, although  unless your rig has a problem with a mismatch of around 1.8:1, I would not bother, as the difference in radiated power is negligible (fraction of an S-point).

Because of the short wavelength, 10m antennas don’t have to be that high to be effective. When the band is in good shape, worldwide DX can be had with simple wire antennas and low power. It is a rewarding band.  What is more, 10m multi-mode transceivers can be bought at low cost.  In summary, 10m is unique: low cost transceivers, simple antennas and good DX potential.

A radio amateur in Nottingham,Vic G0RVA, recently bought one of these Belcom rigs. It appears to be an all-mode 70cm rig, although I am not familiar with this unit.

I know Belcom did a 2m version (the famous Liner-2, which I did once own) and a similar version for 70cm. The Liner-2 was a modification of their 10m version, which I don’t think was ever sold in the UK.  Inside Vic’s rig was what looked like a canned preamp with the marking “AngleLinear” but again I am not familiar with this unit. Angle Linear appear to be based in the USA http://anglelinear.com/ .

In its day, the 2m Liner-2 transformed 2m. It was a synthesised SSB rig and was frequently pushed too hard so that splatter was a problem. I was amazed how far I could work on 2m SSB with 10W pep. From Cambridge I could work stations that would have been impossible on FM or AM. I found I could work 200-300km with a simple antenna under ANY conditions.

Many were critical of these early Belcom transceivers, but I enjoyed my Liner-2 as did many others. Later I bought an ICOM IC202 which was a better radio, but with less ERP. The IC202 had a mock military style, that really was not too clever.

The “coming of age” of 2m SSB marked the change from “tuning high to low” to single frequency working. Sadly, there is far less activity on 2m SSB outside of contests so people think VHF is only really any good for local QSOs. With 10W SSB, or even less, it is possible to work a long way on VHF irrespective of conditions. From my current QTH, I think 200km is reachable with 5W pep and a 3 el beam on 2m. It is not that different on 70cm where I use 5W pep and a 5 el beam. Both my beams are hand rotated.