Rotatable mast bonus

Regular readers may remember that I was asking about rotators some months back. Well, I have just realised that the place where I intend to fix my 2 inch diameter mast at the new QTH is such that I can rotate it by hand by opening a window about 10 feet from my new operating position. This means, if I so choose, I can erect a small beam for 2m and 70cm, or a combined 2/70cm beam and turn it 360 degrees very quickly using the trusty "Armstrong" method. So, initially I'll erect the V2000 vertical but may well add some small (not too sharp) beams for VHF/UHF contest and tropo work. Turning a beam by hand is quicker than a rotator and allows signals to be peaked by ear.

Anyone have any recommendations for a combined 2m/70cm horizontally polarised beam with around 3-6 elements, ideally fed with a single 50 ohm coax? I have seen combined 2m/70cm HB9CV antennas but think there are other options too.

First building projects for the new shack

It will take a few weeks to settle into the new home and get things straight, but already my mind is turning to projects for the autumn. Several of these are hang-overs from the current QTH i.e. "gunner" projects (I'm gunner do this or that!) or projects already started but needing to be completed. This is the list so far. You can be 100% certain this list will grow and change.

1. Check the LF/MF/HF noise environment at the new QTH. I have no real idea how this will be. I am more in the middle of the village at the new QTH, so suspect switchmode PSU and other noise sources may be more of an issue?
2. Finish the 10m WISPY transceiver. Both the direct conversion RX and DSB TX have been built and successfully used on air, but I have still to put the 2 bits together as one transceiver in a box.
3. Finish the optics for my G4HJW designed Finningley optical transceiver. I finished the electronics build some weeks ago but the move got in the way of the mechanical parts. I need a new stable tripod for this too.
4. Carry out some VLF earth-mode tests at 8.97kHz from the new QTH to compare results after the QTH move. My baseline earth-electrode "antenna" will be very slightly shorter and the direction more NW-SE (it was E-W before).
5. Carry out some 472 and 136kHz WSPR tests using the earth-electrode antenna. Again, the aim is to see how results compare at the new QTH. The earth-electrode's new loop direction will affect who can copy me.

Whether I concentrate on HF/MF/LF or move more to VHF/UHF will depend on the noise environment. Although there are plenty of things to try to reduce QRM if this proves to be a problem, it may be the perfect excuse to try something new, such as weak signal QRP work at VHF and UHF. We'll soon know.

Starting to equip new shack

Although our move is a few days away still, I am starting to move my equipment across to the new shack. I may erect my V2000 vertical this weekend too, so that I can have a first QSO from the new shack on the East Cambs 2m FM net on 144.575MHz next Monday at 8pm.

I am debating where to put the triband antenna: either on a gable end over the garage or on a longer pole attached to the rear wall of the garage. The latter would make antenna changes slightly easier as the pole would be attached at ground level, so no ladder climbing needed.

My understanding is that outside of a conservation area I do not need planning permission for a second antenna on the house such as a V2000 vertical as long as the linear horizontal dimension is not greater than 1m, which it would not be. A 2m big wheel on the same pole would probably be OK too. I should be able to string a 10m or 15m dipole from this support to a tree at the other end of the garden that would feed conveniently into the shack just below.

All my antennas now dismantled ready for the move

Today was an historic day: for the first time in around 20 years or more, I have NO antennas up outside at this QTH. The Par 10/20/40 end-fed HF antenna and the trusty V2000 VHF/UHF tri-band colinear were taken down this evening. The V2000 has been up continuously now for the best part of 10-12 years and is in remarkable condition still. Apart from a bit of dirt on the fibre glass covers and a little oxidisation on the metalwork, it is like new and electrically still works perfectly. There are several "copies"  of this antenna around, some of which are nothing like the original version.

It will be some days before I get the antennas sorted and erected at the new QTH, but at least the brackets and antenna hardware are now down and available for a suitable moment.

68-76kHz LF band allocated in the USA

Just in from WG2XRS/4.....

"You might have heard a group of us have received a license covering 68 to 76 kHz with 10 W ERP for most all modes including SSB!  Authorization came yesterday and already have W4DEX on QRSS and into W1VD and others with very solid sigs on 72.4 kHz.  Am gearing up for that operation as we speak.Bob, WG2XRS/4."

This is fascinating news. Although getting anything like 10W ERP is a major challenge at 73kHz, much weaker amateur signals have spanned the Atlantic in the early 2000s when the 73kHz band was available by NoV here in the UK. See  http://homepage.ntlworld.com/mike.dennison/index/lf/transcontinental/2001-2/at2001-2.htm

There is no doubt that some of the US stations will be copied in Europe this coming DX season. Since the first few years of this century a number of new weak signal modes have appeared such as WSPR2 and WSPR15 and OPERA. Also, with GPS locked systems and superb frequency accuracy, it is possible to run very slow CW and DFCW modes knowing that the TX frequency can be very accurately set, so the RX can look for the signal in uHz bandwidths to dig it out of the noise over a period of hours. All we now need is for a limited number of 73kHz permits to be again allocated in the UK.

Please note this is NOT a general allocation in the USA: it is a special research permit to a limited number of stations in much the same way as some access to 500kHz and 136kHz has been granted over there. Their FCC does seem to be incredibly slow at getting new bands like 472kHz allocated. I don't know why this is such a problem: perhaps they fear allocating these LF bands will be a threat to homeland security?

New Address with OFCOM

This evening on-line I notified the TV licence people of our upcoming address change as well as notified OFCOM of my new address.  It is now unlikely I shall make any further QSOs from my current QTH as the last remaining antennas will be coming down next week. Getting my VHF/UHF vertical up is a priority at the new QTH although there are a few more pressing issues to deal with first - like getting some carpets on the floor!

On the front cover of Practical Wireless this month

Well, I had quite a surprise when the Sept 2013 edition of Practical Wireless (PW) magazine dropped on the mat in the post this morning. Although I knew my review of the Wonderwand Wonderloop was inside, I did not expect my bald head to be the subject of the main cover image! My wife Lis took the photo in the back garden of our current home.

I hope those reading the Wonderloop review will think it a fair one. The loop is tiny and uses thin 1mm wire, yet the performance was actually pretty good considering its size, averaging a couple of S-points down on a decent back garden antenna. As the review shows, some good results were obtained.

May I recommend you buy PW as there is a reasonably decent selection of articles in it most months. It is now the only independent amateur radio magazine published in the UK. I do miss the old Short Wave Magazine which was a good magazine in its heyday back in the 1950s and 1960s.

20m WSPR with 0.5 to 2W

As I wind down activity from this QTH before my move, I have been allowing my WSPR beacon to run on 20m using an indifferent wire antenna strung to a low tree at the bottom of the garden. At its lowest point is is only about 2m above ground. Power out has been 500mW or 2W. The results below speak for themselves: WSPR spots from across the planet.

20m WSPR unique spots in last day or so

These are just some of the unique spots: the actual list goes on and on down the page. I am a real fan of WSPR for checking rigs, antennas and propagation. It is also a way to still enjoy the hobby whilst packing up books, CDs, DVDs and other household rubbish in preparation for a house move!

Reflex Receivers

In the days when semiconductors were very expensive parts, the reflex receiver was a very popular design for AM broadcast and simple amateur AM receivers. The basic idea is to use a single transistor is several different ways: as an RF amplifier, possibly a detector and then finally as an audio amplifier by clever feeding of the RF and AF signal back around the transistor. Even today they are fun circuits to try. For example, see the schematic at http://www.ke3ij.com/reflex.htm . Rick has a number of novel circuits on his site.

http://www.ke3ij.com/reflex.gif

In Rick's circuit, Q1 first acts as an RF amplifier. The 1N4148 rectifies the signal which is again applied to the base of Q1, which is now used as an AF amplifier stage. Although adaquate level is available on the collector of Q1 to drive a high impedance earpiece, Rick added another low cost stage to drive an 8 ohm speaker.

Another example of a reflex circuit is at http://www.sm0vpo.com/rx/reflex_rx.htm . Perhaps the most famous reflex circuits came from Sir Douglas Hall in a series of circuits in Radio Constructor back in the 1960s and early 1970s. Some of these are collected at http://www.spontaflex.free-online.co.uk/ . Sir Douglas was a UK overseas diplomat and a very nice gentleman. One of my old school friends lived in the same Devon village and visited him to try some of his prototypes.

Speech processors

Earlier today someone asked me to forward them some links I had on speech processors. This reminded me of a VERY effective speech clipper I built many years ago for a 2m AM QRP transmitter. The audio pre-amp had 2 stages of 6dB/octave pre-emphasis followed by very hard clipping and an active low pass filter to keep >2.5kHz audio levels to very low levels. The signal sounded remarkably punchy and allowed this little 100mW AM transmitter to punch well above its weight. It sounded like a rig running several watts. At some point, after we move, I'd like to replicate the design and give it a go again. It was based around the audio stages I used in the Pye PF8 PMR handheld but with value changes to increase the gain and add the second pre-emphasis stage. Double pre-emphasis meant that there was less clipping at lower audio frequencies and more at the higher end. Compressors are meant to be better, but honestly this little circuit took some beating.