AmateurRadio.com

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.

Owen Morgan, KF5CZO, is a regular contributor to AmateurRadio.com and writes from Texas, USA. Contact him at [email protected].

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

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

Scott Hedberg, NØZB, is a regular contributor to AmateurRadio.com and writes from Kansas, USA. Contact him at [email protected].

I first noticed these antennas a few months ago. They look interesting. I’m looking forward to getting my hands on one and trying it out.

Here is the press release…

FOR IMMEDIATE RELEASE:

British Antenna Company InnovAntennas Appoints First American Dealer

Glade Park, Colorado – January 23, 2012 – The full line of high performance HF, VHF and UHF amateur radio antennas from fast-growing British company InnovAntennas are now available to customers across the United States via Hamilton, Ohio’s R&L Electronics.

“Our customers have been hearing about the outstanding performance of InnovAntennas’ designs from their amateur radio friends overseas, reading about them in European journals such as DUBUS and from a handful of ‘early adopter’ American hams who couldn’t wait and purchased InnovAntennas products direct from the UK,” said R&L Electronics’ Roger Smallwood. “We are proud to be the first American retailer to represent this exciting new brand.”

InnovAntennas was launched in 2011 by Justin Johnson, G0KSC, after his hobby of designing antennas for his personal use led to a flood of requests to “make one for me” from amateur radio operators who recognized that Johnson’s designs outperformed they could buy in a store. Today, InnovAntennas is building antennas at a former boat factory in Canvey Island, England and selling its products directly via InnovAntennas.com and via a network of dealers in Europe, Australia, and now, the United States.

InnovAntennas’ highly regarded designs include LFA (Loop Fed Array) and OP-DES (Opposing Phase –Driven Element System) Yagis. Performance of GOKSC designs routinely top the charts in their boom-length class on the survey of ‘moonbounce” antennas –“EME-ers” are among the ham world’s most demanding operators –compiled by VE7BQH and available online.

InnovAntennas America’s William Hein said “We selected R&L as our first American dealer due to their commitment to customer service, deep inventory, high order fill rate, great history, product knowledge and enthusiasm for InnovAntennas’ approach to design and construction. We look forward to a long, productive relationship with the gang from HAMilton OH!”

R&L’s Roger Smallwood added “We work hard to have all ham radio products in stock and ready for immediate shipment. From a 50 cent connector to the thousand dollar radio, our customers will receive the same fast service at a great price. No one likes to hear that an item is out of stock or it will be drop shipped from the manufacturer. We already know InnovAntennas are high quality products and will be very well known in the USA in a short period of time. Our goal is to have it in stock when you are ready for it!”

Matt Thomas, W1MST, is the managing editor of AmateurRadio.com. Contact him at [email protected].

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!

Alex Hill, G7KSE, is a regular contributor to AmateurRadio.com and writes from Cumbria, UK. Contact him at [email protected].

The other day I received an email from the Elecraft reflector site mentioning Plasma TV's and the problems they can cause ham op's. I do have a Plasma TV and it sure does affect things here at VE3WDM so this thread interested me very much. As you know from reading my other posts I do have the MFJ 1026 noise cancelling unit and I have had good success with it. The post on the Elecraft reflector had a great link to a load of information on how the K3 and the MFJ 1026 can work together very well. Well since I have the K3 and the MFJ 1026 I investigated the link.  I found a very cool way to hook the both units together that
has some good advantages over the way I am now......or was using.

 With this configuration I am able to just push the RX ant button on the K3 and both units are inter connected. Also the way the MFJ 2026 is adjusted is a little different than I had previously adjusted the unit. I tried it and it is very easy, fast and works great!! So what are the advantages of hooking up your MFJ 1026 this way....well you never have to worry about the RF from your transmitting antenna getting into your receive antenna. With this hookup they are totally isolated. To include the MFJ 1026 it's as simple as powering up the MFJ unit and pushing the RX ant on the k3 and then some simple adjustment of the MFJ unit. Finally I decided to use my Iphone to video the results of the MFJ 1026 and the K3 and how they dealt with the Plasma TV noise. You will have to excuse the reflection of me in the Elecraft P3 and the audio may not be that great either but give it a go as it does show how the Plasma TV's interferance can be dealt with.


Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

Today I have been playing around with MEPT beacon code on my Gadget Gangster Parallax Propeller board. First I wandered over to Jeff, KO7M’s blog and borrowed his WSPR beacon code.

Gadget Gangster in use as a 25mW WSPR/Opera beacon

WSPR was the thing I originally wanted to try when I decided to get the Gadget Gangster: I hadn’t even heard of OPERA at that time. But I was unsure whether I would be able to generate the FSK frequencies WSPR uses: four tones separated by about 1.48Hz. Jeff decided to shoot as near as he could and programmed for a 2Hz separation of tones, and found that the signal was decoded by K1JT’s WSPR program. So no problem!

I measured the RF output from the Propeller board and it was somewhere in the region of 25 to 40mW, depending on which measurement method you believe. I also looked at the output using my oscilloscope.

Output waveform from Parallax Propeller on 80m

It wasn’t a pure sine wave, there’s obviously some harmonic content there, but it was not as bad as I feared it might be. As I would be using my MFJ magnetic loop on 30m, which has a very narrow bandwidth, I decided not to bother with a low pass filter for the sake of these initial trials. I watched the seconds tick over on my shack radio-controlled clock, started the beacon and was soon rewarded by several WSPR spots!

WSPR spots for 25mW Propeller beacon

Because WSPR is a time-synchronous mode I had to start the beacon when the seconds ticked over to 00. This brought to light a problem Jeff had already observed: the Propeller drifts. The drift seems to be worst during the first few minutes of operation, so leaving the beacon running so it can reach a stable temperature would appear to be the solution. However that is not so easy when you have to power it on at an exact time. I will need to look in to implementing a real-time clock for WSPR, unless I want to interface a GPS receiver to the Propeller – which is certainly possible and something else I hope to try as I’d like to have a go at making an APRS tracker.

An advantage of the OPERA mode is that it is not time synchronous so I can leave the beacon running in that mode with an arbitrary delay between transmissions. My first OPERA transmission also produced several spots, including reports from fellow bloggers PC4T and G4NKX.

OPERA spots for 25mW Propeller beacon

I can also generate Morse and QRSS beacons using the Propeller chip. There is still a lot to do to reach my goal of a multimode, frequency-agile beacon, including adding a PA and some switchable bandpass filters. But so far this project has turned out to be easier than I thought it would.

Julian Moss, G4ILO, is a regular contributor to AmateurRadio.com and writes from Cumbria, England. Contact him at [email protected].

Yes, I am still alive. With the end of the year and the end of a semester at school there was too much going on to sit down and write something properly. But if you have followed the blog on my website you know I have been a bit busy with the hobby after all. The itch has to be scratched somehow.

Chinese New Year is upon us, which means a lot of festivities here in Asia. Expect some more activity on the bands from China and Taiwan as this is the only time of the year that people get some longer time off from work. The coming year is the year of the Dragon and I live in Longtan (meaning Dragon Lake) so my new QSL card will have to be based on a dragon as well. Stay tuned.

After a busy half year it was time to relax a bit and so we went to the southern tip of Taiwan last week. Temperatures were such that the kids could play on the beach and me and my wife could lounge on deck chairs. I didn’t take a radio with me, but still had an interesting encounter with amateur radio.

In the taxi to the National Museum of Marine Biology and Aquarium I noticed the driver had a 2m/70cm rig in his dashboard. So I asked him for his call sign. Instead he gave me his on-air handle. So I asked him again, explaining that when he applied for a licence he got himself a call sign beginning with BM (which is the prefix for the third or entry class station licence). He didn’t remember, because it was over ten years ago that he took the exam and why use a call sign anyway, everybody knew him by his handle? He only uses his rig to communicate with other drivers to warn where the police has put up speeding and alcohol checks.

And that, ladies and gentlemen, is how amateur radio works in Taiwan. Or as I saw it on a Taiwanese forum: “The third class licence is simply to legalize the ‘sausages‘ out there.” CB radio, but with a licence. Happy Chinese New Year to you all!

Hans "Fong" van den Boogert, BX2ABT, is a regular contributor to AmateurRadio.com and writes from Taiwan. Contact him at [email protected].