AmateurRadio.com

GB4LBC has now shut down, we’ve amassed quite a few contacts over this weekend to add to our haul from last weekend as well. The loan of the old shop from St Bees lifeboat was very much appreciated by all of us that got involved. I managed to get a couple of 2m FM contacts from the top of the headland before the battery died on me and fired up the Monday night intercontinental special (loosely based on just about every other vertical but with one exception – It wasn’t resonant on the band it should have been). I’ll check it with the analyser shortly to see what I’ve managed to do with it but even when it was tuned by the autotuner and at an awful efficiency no doubt I managed a couple of DX contacts to add into the book.

Over the next few days I’ll be collating all the log sheets we have and totting up all the contacts. I’ve got quite a few to do. We seemed to be more popular than we bargained, so it’ll take a bit of effort to sort out the QSL cards and awards.

Norman, G7MRL, Noel, G4PEW, Liz M6EPW and myself will undoubtedly be back next year and hopefully colin, M0XSD can do better with his lurgy timing with our muddy antenna installation and modest transceivers to do battle with high winds and rain as well as frozen soil so thanks to everyone who answered our calls, forgave our ability to forget your callsign, call you by someone else’s name or listened without switching off to us repeating ourselves with the same facts and figures that we’d handed out in the previous over. You’ve all made our 2 weekends of SOS Radio week enjoyable and most of all memorable.

GB4LBC going QRT

Well, that has to be the longest day I’ve ever spent at the mic. Both Norman, G7MRL and myself have been at the coalface from about 8am. The morning sun was just starting to peep through the fells and made for a lovely sight. The bonus was that the ground that had been boggy and muddy last week was stiff with the hard morning frost and it made setting up the mast much easier.

Lovely morning for radio

The St Bees lifeboat station manager has been so helpful and not at all concerned by our muddy footprints that have given away our movements on his clean floor. We’ll need to clean it up properly tomorrow afternoon.

Conditions weren’t as good as last weekend. The band seemed to have a lot of static in the morning and QRM at lunchtime followed by bedlam in the afternoon with stations on top of each other on 40m. 20m was contest town and we only managed 1 contact before be gave it up as a bad idea. 17m, 12m and 10m gave a few contacts including Greece on 10m FM, which was nice.

Both Norman and myself had a tiring day and at 3pm headed back to 40m for a few more QSO’s. We’re back on the air tomorrow although I’m on home duties in the morning but Noel and Norman will be on in the morning. Perhaps I’ll get a chance to use my 6m 5/8 vertical.

Anyway, although it was a tiring day we couldn’t have filled 5 pages in the log without everyone coming back to our CQ call. Without those patient people who  helped us when the conditions were against us. The number of stations that wanted our little extra award certainly helped get the numbers up. I’ve a sneaking suspicion that GB1LBC will be in big demand tomorrow after Bill had to call it a day with feeder troubles today.

After my grandfather passed away I spent a lot of time recalling the good times I had spent scrounging around his CB shack and hanging out with Pop “down the shed”. If you’ve spent time around old motorbikes, retired lawn mower engines, vacuum tube electronics and inches of dust you know what the shed smelt like and probably have a pretty good idea what it looked like as well.  I used to be able to send Mum into fits by embedding a combination of oil, grease, dust and grinding compound into the knees and sleeves of my good clothes after spending the day “over south” (South Geelong)

Even now I can still walk into any old auto mechanics and the smell brings back dozens of memories as clear as day … but one memory in particular had been bugging me for a while now. On several occasions I had used a magnificent rack mounted shortwave receiver that had been hooked to a long-wire antenna between the shed and the house. It had several plug in coils housed in bright metal boxes, one for each band as well as a unique tuning dial that had windows around the circumference with numbers that updated as the dial was turned.

National HRO right? … Nope, its an Australian clone!

For the longest time I was thinking what you are probably thinking now, I had been using a National HRO receiver right? Well, you’d be wrong … just as I had been for years! When I eventually asked my uncle about the receiver (I waited a long time as I feared it had been thrown out & honestly didn’t want to know if it had) he said, “The AR7?” … “Yes, its here in the garage covered in dust”. He went on to say that I could have the receiver if I could figure out some way to ship it … not a slight problem given the receiver, power supply and speaker are over 120 lbs!

Knowing now that I had been using a completely different receiver I set to work and found out what I could about this National HRO clone …

From : http://www.vk2bv.org/

The AR7 was produced during WW2 by Kingsley Radio of Melbourne for the R.A.A.F. These receivers were used in ground stations for long range communication over fixed circuits as well as for receiving signals from aircraft.

The AR7 was based largely on the National (USA) HRO model, a fact that did not go unnoticed by National. This was the subject of litigation during the war years. Over 3000 of these receivers were produced and for their time, produced excellent performance.

These sets were very popular with radio amateurs after the war and unfortunately subject to many modifications. The Wireless Institute of Australia station, VK2WI at Dural New South Wales was equipped with modifed AR7’s for many years. I seem to remember that very local operators could block the receivers completely, resulting in hurried phone calls!

An unmodified AR7 is a rare beast. The Department of Civil Aviation used these sets for many years in a highly modified form, requiring a new front panel. Refinements included squelch and crystal locked coil boxes.

From : http://www.shlrc.mq.edu.au/~robinson/museum/AR7/

The AR7 is a communications receiver covering LF and HF bands. It was made in Australia during 1940 and bears an extremely close resemblance to the National HRO receiver. The receiver has a tuning range from 138 kcs to 25 mcs, with a gap of 45 kcs either side of the 455 kcs IF amplifier. The internal design is a single conversion superheterodyne receiver with 2 RF stages, 2 IF stages, a BFO and an “S” meter amplifier. The sensitivity is quoted as 1 microvolt. The front panel is stainless steel and  it is a very distinctive looking receiver.

It is a good performer, sensitive, has a nice feel, is easy to tune, but hard to find the correct frequency, by reading the frequency from the dial number and coil box graph. It really needs a crystal calibrator.  I use it for the weekly W.I.A. (Wireless Institute of Australia) broadcast, so it gets turned on once a week, and is so stable, than I don’t have to retune. It is very clear for AM but a bit fiddly for SSB.

The controls are: RF gain, BFO note, AVC/BFO switch, Adjust “S” meter, Tone, Tuning, Noise limiter, Selectivity, Crystal IN/OUT switch, Crystal Phasing, Audio gain. The Audio gain control has an OFF position which removes the HT so that the coil boxes can be changed.

It has two 6U7G RF stages, a 6K8G mixer, two 6U7G  IF stages at 455 kcs,  a 6G8G detector/AVC/audio preamplifier, and a 6V6G audio output amplifier. It has a 6C8G twin triode as a BFO and “S” meter amplifier. It also has a crystal filter. The IF alignment should be done very carefully, as any misalignment will reduce the effectiveness of the filter. It is best done with a sweep generator. The 6 volt valve heaters are connected in series, for 12 volt operation.

The external power supply and speaker, are usually mounted in a short 19″ rack, the AR7 at the bottom, the speaker in the middle, and the power supply at the top. The complete unit weighs about 118 pounds. The power supply was switchable between 12v and 240v.

The receiver was used as a ground monitoring receiver for aircraft. It was extremely stable. The model shown has an R.A.A.F. nameplate, and serial number 1786. The manual I have is a D.C.A. (Department of Civil Aviation) version and is a 1947 issue.

It has 5 plug in coil boxes. The coil boxes are: band A 140-405 kcs, band B 490-1430 kcs, band C 1.420-4.3 mcs, band D 4.25-12.5 mcs, band E 12.5-25 mcs. The Army version had an extra coil box covering 50-150 kcs. The large dial is a 20:1 reduction drive and has graduations from 0 to 500. It acts like a flywheel when tuning across the band, and has an effective scale length of 12 feet. The dial shaft goes into a right angle reduction gearbox and has 2 output shafts that drive 2 dual gang capacitors. The graph on the front of each coil box is used to covert the dial reading to frequency.

These are the QSL card designs that didn’t make the final cut:

… it was kind of tough not going with the Delorean.

Oh joy, my email seems to have been hacked into.
Apologies to anyone who has received any helpful advice they didn’t really want from my account.

I’ve spent the best part of an hour changing passwords and resetting things and this site hold no ‘email-able’ information so there shouldn’t be any coming through but if you’ve been got then I apologise and I’d like to say it’ll never happen again but you know how it is.

It happened at 8.37am today and the password was changed by 9am so it was the best I could do.

Very annoyed about it!

It been a real pleasure to be operating the GB4LBC special event station for SOS radio week today. With just a long wire and 100w we had our own little pile up which lasted pretty much all day.

The station will be up and running again tomorrow on 40m and hopefully will be just as popular. The Workington and district club (MX0WRC) is operating 3 of the 4 stations in Cumbria

GB1LBC – Silloth
GB2LBC – Workington
GB4LBC – St Bees
GB5LBC – Barrow in Furness

GB5LBC is operated by our friends at Furness ARS and we managed to have a quick QSO during the pile up

ZL1HIT (Bryan Rentoul) has bridged a gap of more than 80 years by combining the text transmission system developed by Rudolf Hell in the late 1920’s with current microprocessor technology.

A sample of received Hellschreiber test from Bryan’s beacon

Hellschreiber sends a line of text as a series of vertical columns. Each column is broken down vertically into a series of pixels, normally using a 7 by 7 pixel grid to represent characters. The data for a line is then sent as a series of on-off signals to the receiver, using a variety of formats depending on the medium, but normally at a rate of 112.5 baud.

This process was historically accomplished with mechanical equipment but there are very few examples of this equipment still in operation and it is now sent and received by computer. Hellschreiber is very tolerant of noise and interference and requires only simple transmitters and receivers to work effectively.

German Hellschreiber unit in operation

With a microprocessor generating the digital on-off signals a simple crystal oscillator transmitter can be used to form a beacon station, one that transmits a call sign and perhaps some other information over and over. Changing the transmitted message is as simple as reprogramming the microprocessor or having it respond to a connected input, for Eg. A thermometer, light sensor, switch, etc.

Receiving the signal and decoding requires a radio receiver capable of CW reception and a computer running any of several free software packages like FLdigi or Digital Master 780.

The ZL1HIT beacon using a PIC microprocessor and a simple crystal oscillator transmitter.

For more information and the PIC microprocessor source code please visit the web page of Bryan Rentoul here : ZL1HIT Hellschreiber / PIC Beacon