AmateurRadio.com

There was a knock on the door this morning and the postman asked me to sign for a parcel from overseas. The customs declaration amusingly – if appropriately – described the item as “Toy”. It was the UNI-T UT-81B Oscilloscope Digital Multimeter that I ordered last weekend from eBay seller hk360radio in Hong Kong.

My first thought on opening the box was: “Wow! All this for a hundred quid? Amazing!” Inside the zip-up fabric carry case was the scope/multimeter, test probes, a BNC oscilloscope probe adapter, an opto-isolated USB cable for connecting the instrument to a PC, a two-pin wall-wart power supply and a two-pin to UK three-pin mains adapter, manual and CD containing the PC software.

The instrument is both a multimeter and a storage oscilloscope. The multimeter is auto-ranging, so the control switch simply selects the function: voltage, current, resistance etc. It measures DC voltages to 1000V, AC to 750V, current to 10A, resistance to 10M, capacitance to 100u and frequency to 10MHz. There is also a continuity tester. It can read volts down to 100uV and current down to 0.1uA. The frequency counter accuracy isn’t good enough to calibrate your radio, but it’s still quite handy.

Many years ago, back before I had a ham radio license, I had an oscilloscope that I built from a design in Radio Constructor magazine. It only covered up to about 200kHz and wasn’t calibrated. I had to sell it when I left my parents home and had nowhere to keep so much electronic stuff, and I haven’t had one since. But there have often been occasions when I wished I had one, so that was one of the main reasons for buying the UT-81B.

The oscilloscope bandwidth of the UT-81B model is quoted as 8MHz, so I can’t use it as a monitor scope for the whole of HF, but it covers up to 40m at least. I was very keen to try this. I connected my FT-817 up to my QRP power meter via a T-piece and connected a cable between that and the oscilloscope. When I spoke into the microphone I could see the modulation envelope on the display.

I was interested to see whether the horizontal scan rate was fast enough that I could see the actual RF waveform. I increased the timebase speed until I was able to see the display above of the carrier wave from the FT-817 in CW mode. The sample rate is given as 40MHz and you can just see that the waveform is a little jagged. You can see that the scope has also displayed the frequency to within 1kHz. There is a full range of trigger functions and also a manual hold you can press to capture the display, which I used to take the photo above.

There is a Windows software application that connects to the instrument via a USB port. It can log measurements over time and also capture scope displays and save them to a bitmap (BMP) file. I was able to capture the waveform shown in the photo. However it was not able to capture an RF modulation envelope when sampling the RF at a much slower time base setting. I just got a thin wiggly line that seemed to bear no relation to the envelope displayed on the scope itself. Not a major issue, though.

I am really delighted with my new “toy”, which cost me £95.50 plus £13 for the shipping (and no tax.)

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

Suppose you were a member of a village football team that had practised and played on the village green for years. And suppose that one day you turned up for a game and found a new rugby team using your pitch. You’d be pretty annoyed, wouldn’t you? Even though the village green is common land and so legally there for all to use, the football team would not expect its use of the football pitch established over many years to be usurped in this way. So it isn’t all that surprising that when it is, there’s a punch-up.

Turn now to the amateur bands and this is precisely what has happened to users of the Olivia data mode. Someone has turned up with a new game called ROS that requires a much larger pitch and it is interfering with the Olivia users’ ability to play Olivia.

OK, you say, but surely no-one could object to the rugby team using the football pitch when the football team isn’t using it? It’s a fair point, although as the football team uses the pitch off and on throughout the day they wouldn’t be happy about it. But here the analogy starts to fall down, because not only do the football team (Olivia) and the rugby team (ROS) not speak the same language, but they are also blind so they can’t see each other to ask even if they were able to.

The only way for the two teams to both play on the village green without falling over each other or resorting to fisticuffs is for each of them to have their own, separate pitches. Now could someone please translate this into Spanish and show it to the coach of the rugby team?

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

A few weeks ago I made a rubber duck helical antenna for my TH-F7E. I didn’t get around to writing about it at the time, plus it took a while to get some reports of its performance.

Well, it works extremely well, and I have just added a description of how to make it to the main G4ILO’s Shack website. See A DIY Ducky for 2m.

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

I’d sworn I wasn’t going to post any more about the ROS digital mode, or even mention it by name again, but the latest bizarre twist in the tale is too much to resist. Here’s the story.

On March 3, Dave AA6YQ called the FCC to confirm whether the statement that ROS was now legal for use in the US which had been posted on the ROS website and which I wrote about on Tuesday was true. The FCC advised that the information (which has since been removed) was not true, and that the matter was still under review. Dave was told that the ARRL was involved and would publicize the outcome. This they have now done, and the outcome is that ROS remains illegal for use in the USA on frequencies below 222MHz.

ROS may still be legal in the rest of the world but I have to ask whether amateurs in Europe and elsewhere really want to be using a mode developed by someone who posts false information and rude remarks on his website and issues threats to any amateurs (including myself) who dare to make any statement against his mode. This is not mature, responsible conduct nor is it in the spirit of amateur radio. We don’t need this sort of behaviour which has come close to bringing the hobby into disrepute. It might be for the best if everyone stopped using ROS altogether. It isn’t as if there aren’t already plenty of other digital modes. And be honest, a mode that offers no chance of working any North American DX is not as interesting as one that can, is it?

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

As someone who has quite often used WSPR, I have often said that it would be nice to be able to exchange reports with other stations and confirm the “contact”. I felt this simply because the WSPR network is a friendly community and it feels right somehow to be able to do that, just as you would confirm an enjoyable contact on another mode.

Modes like the little used WSPR QSO mode and JT65A on HF offer the chance to make two way QSOs using similar power levels to WSPR. But my recent experience using JT65A on HF, and more recently watching a station in Iceland take half an hour to try to exchange a signal report and confirmation with a station in Brazil using a certain other weak signal mode led me to wonder if in trying to make it possible to make “contacts” using the least possible power we have thrown the baby out with the bath water.

Communicating via moonbounce (EME) on VHF has always been about exchanging the barest minimum of information, because even doing that is a major achievement. But on HF it is always possible to have a proper contact, even if it means using a bit more power or waiting until propagation is a bit better. So why are we endeavouring to use modes designed for EME on the HF bands? What is actually being achieved? Someone’s computer is able to pick a few characters of information out of my barely audible signal, with the help of heavy error correction and the fact that the message format is known. My computer is able to do the same with his. Is this actually a contact?

Yesterday I tried for the first time in several years to use the Olivia digital mode. Before I did, I Googled up some information about it, and came across a Yahoo group containing a post by Waldis, VK1WJ. He wrote: “Yesterday I had a sked with DJ2UK on 20m in JT65A. Bert came in with around -17dB but he couldn’t decode my signal. After a while I saw in SPECJT that he had switched to Olivia 8/125. So I did the same, and we had quite a long error-free QSO. Olivia 8/125 is not exactly fast, but it still beats JT65A hands down. May be we could entice our JT65A friends to try Olivia instead?”

According to Waldis, instead of exchanging a couple of numbers using JT65A, you could have an actual (if slow) conversation using the 8/125 variant of Olivia. But the JT modes are currently in vogue, whereas Olivia – being developed in 2003 – is yesterday’s news. People are raving about the capabilities of a certain other mode that is making a lot of news recently. Have all these people actually tried some of the forgotten modes? Because I think if they did they might wonder what all the fuss was about and whether the newcomer really justifies its use of bandwidth.

What was I saying about reinventing the wheel?

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

I've preached before about the problems posed by proprietary software in amateur radio, namely the D-STAR AMBE vocoder.  I won't rehash the issues with the AMBE vocoder, but some recent events with a newly introduced digital mode (that will remain unnamed in this article) illustrate some of the problems with modes that are totally dependent on closed source software and/or proprietary algorithms.

The author of the new digital mode software became upset with several bloggers and forum posters and decided to prohibit them from using his software and any future software projects or modes created by him.  He created the software, he owns the copyright, so he do with it nearly whatever he wants.  Since his software is not open source, the author can add whatever code he desires into the product, without third party scrutiny.  He could easily put functionality into the software that makes it become inoperable if the callsign of a prohibited user is entered into the configuration.  The software could allow a prohibited callsign in the configuration and allow QSOs to be established, however the software on the other end of the QSO could recognize the prohibited callsign and automatically terminate a QSO, thus cutting off the prohibited user from the rest of the amateur radio community and embarrassing him on the air in the process.  Outside of enabling vendettas against certain radio amateurs, the software could be enhanced with more features in the future (better performance, higher speed, etc.) and such features would be given only to users who pay for a premium edition of the software.

Obviously the examples above are purely fictitious and as far as I know haven't been done, but they're certainly within the realm of possibilities.  With commonly available software libraries and cheap software development tools, most anyone can create a new digital mode today and as we've seen it doesn't take much for a new digital mode to "go viral" like a popular YouTube video.

I'm not an open source fanatic, but we're setting ourselves up for some bad scenarios if we continue to adopt closed source software and proprietary algorithm modes.  Will ARRL or some organization take a stand against this?  Or are we going to continue to drink the Kool Aid just because it tastes sweet?
Anthony Good, K3NG, is a regular contributor to AmateurRadio.com and writes from Pennsylvania, USA. Contact him at [email protected].

Photograph 1 depicts our first attempt at helically winding 97 feet 1 inch of AWG#14 wire on 2 inch PVC SCH40 before re-thinking our strategy. I opted for removing the long screw driver on the wire spool and approached our problem like taping a piece of pipe. I maintained upward and downward tension using the spool.

Photograph 2 facilitated third person in this operation because handling a 10-foot piece of PVC is difficult to balance while winding.

Photograph 3 demonstrates our solution in addition eight inch lengths of halved duct tape at every 12th or so wind. We found taping at this interval suitable enough to maintain adequate tension. I attempted, to the best of my ability, half inch spacing between winds however I’m not satisfied with the quality of my work. Therefore, the next step in our project, includes adjusting each wind accordingly.

Photograph 4 illustrates the end result of three hours of labor. My plan is to replace the spade located at the binding post while spacing each wind according to K6MM’s instructions. We divided each each section by the total length that is 256 feet 5 inches of wire equaling an average of 85 feet per section. Additionally, I’m purchasing alligator clips for each section because I’m intending to deploy the antenna in the portable mode.

Believe in your signal!

Scot Morrison, KA3DRR, is a regular contributor to AmateurRadio.com and writes from California, USA.