Using the excellent Radio Mobile program by Roger VE2DBE, I’ve produced a 144.3MHz coverage map for our current setup at the club-house. For info about the antenna, losses, power etc see the first page.
The report is here.
Andrew
G0RVM
Members who attended tonight had a talk about the types of propagation commonly used at VHF by radio amateurs.
The slideware from the talk, along with material from other talks, may be found in the Lecture notes section of the TSGARC website.
Andrew, G0RVM will be giving a talk on VHF Propagation this Wednesday evening (5th Oct) starting at 19:45 hours.
The talk will be an introduction to the most common modes of propagation at VHF and their use by radio amateurs.
Strange hot weather but good conditions on 2m 🙂
Monday 5th and Tuesday 6th September very busy on 2m. At times tonight every 10kHz step and often 5kHz step was busy. Great to see/hear. Worked F8IQS in Caen on CW. His signal was easily 599!
Even bumped into another club member, Steve, M6JJV working contest from Berkeley 🙂
Andrew
G0RVM
As some of you may be aware, last weekend I went to Guildford to attend this year’s EMF camp. Electromagnetic Field is a camping festival geared towards hackers and makers. The weekend is filled with interesting talks, demonstrations and crazy projects.
Arriving on Camp
My idea of a camping trip!
I arrived on site with a reasonable idea of what to expect, but this was reinforced when someone whizzed past me in a Sinclair C5. This turned out to be only a taster of what was to come.
I was to be joining a group of amateur radio enthusiasts who were running the EMF hams village. There were 16 of us and we had all come with a variety of equipment. Using the special event callsign GB4EMF, we operated using the following stations:
This was all made easier by the network of datenklos (data-toilets). These were power and networks hubs being kept dry using porta-loos. Over the weekend we maxed out at over 100kW pulled off two generators, 66 Wi-Fi access points, 4500 networked devices and 3.5TB of data going between our network and the internet.
Things to see
There was a lot of ‘stuff’ at EMF this year. A few honourable mentions go to the high altitude ballooning village, fire pong, just add sharks laser cutters, blacksmithing tent, lockpicking tent giant guitar hero, the music powered quadruple flamethrower, retro arcade tent and the amateur radio village of course.
JustAddSharks Laser Cutter
HABville’s weather balloon tracking station
Pub sign!
Overall EMF camp this year was a fantastic event, full of technology and ideas. The talks I attended were very interesting, and all available of the EMF Youtube account. I’m definitely signing up for the event when it next runs in 2018. For more info see emfcamp.org, wiki.emfcamp.org, and for more photos see https://www.flickr.com/groups/emfcamp/pool/.
View of site
PS: I’ve got my new callsign, 2E0UAR
-Peter Barnes (M6KVA, 2E0UAR)
Friday 29th April saw the start of the TSGARC big Field Weekend. OK, not quite the same as its BBC Radio 1 namesake but just as much fun 🙂 Setup took place on the Friday and was finished by late afternoon – much quicker and more smoothly than last year. The event ran over the following Saturday, Sunday and everything was dismantled and removed by mid-Monday afternoon.
So a big thanks to those that came and who helped setup and/or remove everything. An event like this was only possible thanks to some accommodating friends of John, M6EQQ who allowed us to use their field. As a thank you the club bought them a bouquet of flowers and some beer. I will let you work out who received what! Like preceding days, the Monday was a relaxed start and the dismantle job only started late morning. Unfortunately, as some people know only too well it started raining just after lunch which incentivised speedy work. But some of us got a little damp – Rex 😉
Over the whole weekend there where two radio tents, the first used the FT-897 loaned to the club by Derek. This allowed HF and VHF (6m) operation using a G3TXQ Hexbeam from MW0JZE (top image). VHF (2m) operation was possible using a 9-element Yagi from Tonna. The FT-897 PA provided 100w on HF and 50w on 2m. The highlight of the first day was a solid 17m contact into Japan by Derek using SSB. But there where also lots of other contacts across the European and American continents. The hexbeam was observed to have useful directivity mounted at 12m atop the trailer tower.
The second tent used a home-brew HF (20m) Bobtail – orientated to provide East/West lobes – and a 3-element Yagi for 2m, both courtesy of John M0HFH. This tent used the clubs FT-450 both for SSB and CW plus an FT-857 and FT-817 provided by John and Rex. The tent also showed rebellious tendencies, opting at times, to use some rather exotic batteries which no-one wanted to be anywhere near!! Thanks John!
There, was of course, another tent, a very important tent and one where people congregated. The ‘brew tent’ was where we had the stove, tea, coffee and what seemed like an endless supply of bacon – thanks Jane – plus copious amounts of biscuits 🙂 The weather was mostly dry but a little on the chilly side so this was indeed a popular tent.
In total we had two big (6m x 4m) tents, the rebellious tent (2.5m sq) plus a small day tent to keep the generator dry. These provided ample space and shelter for the weekend. The final accommodation to mention was the chemical toilet, arguably the most important item to making the field weekend possible.
Everyone who went had a good time and all the equipment worked well. Simultaneous operation of two HF stations was not really possible, or expected, due to the proximity of the antenna’s so perhaps a project for next time is to make band-pass filters. It was a surprise to find that even HF low power transmissions broke through on the other tents VHF (2m) activity.
With only two radio’s in operation at any time it was common to find people in the ‘Brew tent’ or contributing to activities in the field. In the above image John, M0HFH is being helped to connect an ATU to the feed point of the HF (20m) Bobtail.
There was also some genuine help. Many hands made light work of jobs including raising the tents and preparing the operating positions. Unpacking, assembling and raising the hex beam was made easy with great support. Thanks also to Ron, who stuck it out in the rain on Monday to methodically dismantle the hextbeam such that it can be easily reassembled next time.
Personally, I’m already looking forward to another event next year. But we may move the date back to the late May Bank holiday weekend as the weather should be a little warmer 🙂
Andrew
G0RVM
Santa was kind enough to get me a new SDR radio this year 🙂 It’s very different and will take some getting used too.
Andrew
G0RVM
Over the last few years I have not had to think too hard about ensuring I’m driving my FT-2000 at a good level. i.e. its not being overdriven. It has an Automatic Limit Control (ALC) meter and its been a matter of adjusting the audio amplifier gain such that the ALC triggers occasionally and only on the highest signal peaks. If a good quality transmitted representation of the input signal is to be produced its essential that the equipment stages are not overdriven. I guess we all rely on the ALC and its correct adjustment is second nature, however, take away the ALC function and what do you do? How do you ensure you don’t overdrive the radio or downstream amplifiers? This is the problem I had 🙂
I’m using the FT-2000 as an exciter for my Kuhne Electronic VHF transverter. In this mode the ALC circuitry of the FT-2000 no longer works and the transverter does not output a drive level signal which I could connect to the FT-2000 or to a homebrew ALC meter. But the transverter does have a red ALC LED which illuminates when the drive level becomes excessive.
The signals I’m presenting to the radio are audio and are either voice from the microphone (voice chain) or data from a SignaLink USB audio interface (data chain). Each of these chains has several amplifiers which can be adjusted by an operator:
Ensuring each amplifier is set to a level such that downstream equipment is not overdriven producing distortion and splatter is essential!
So, how did I adjust everything? Well, the transverter documentation says to start by setting the radio to full power (0.1mW when using the transverter connector) in RTTY or CW modes and key the transmitter, then adjust the TX Power control of the transverter to output 20 Watts which should be prior to ALC LED illumination. Having done that using a constant CW modulated signal I had the transverter generating maximum power for a maximum signal drive level from the radio. That set the upper threshold which could not be breached by the voice or data chains without distortion or the transverters ALC activating.
Next I fed the constant CW, RF output of the radio directly into my digital oscilloscope rather than the transverter and noted the signal power. Interestingly, the power levels seemed much higher than the figures stated in the FT-2000 Operating Manual. But from the previous step I knew the transverter was ok with this.
CW Transmission
This allowed the accurate identification of the RF power level driving the transverter and thus the baseline levels for the voice and data chains. The next step was to generate a constant RTTY tone using the computer and adjust the amplifiers in the data chain such that the levels identified in the first step where not breached.
RTTY tone generated by DM-780
Once done, I performed a similar exercise on the voice chain for J3E (SSB). By selecting a cumulative display mode it was possible to record the varying power level over several iterations of a CQ call. As can be seen, most elements of the call resulted in an average level, but interestingly, the ‘G’ or Golf in G0RVM generated significantly more power.
J3E SSB Voice adjustment
The gain of the voice amplifiers in the voice chain were adjusted so that the upper threshold identified in the first step were not breached. The last step was to adjust amplifier gain for A3E (AM). I had expected this to be very similar to the J3E level but it needed to be slightly higher.
A3E (AM) Transmission
AM is not a mode I use very often, if at all, so I didn’t spend too much time adjusting amplifier gain but I did change the gain from the factory default to ensure that the upper threshold identified by the first step was not breached. It could still go a little higher but it will do…
So, the result of all this testing is that I am now confident that using the voice or data chain’s I’m not going to overdrive the radio or transverter. Downstream of the transverter is an RF power amplifier, but that is specified to generate 1kW for 25 Watts of drive, and as I don’t wish to run it at full power, overdriving should not be an issue.
I’ll just add at this point that the above approach is applicable to amplitude modulated signals only and thus not those that are frequency modulated.
Andrew
G0RVM
I could not resist the name of this article, it seemed so obvious 🙂
I’ve been in the radio room this afternoon listening to the 2m VHF band, calling CQ on CW and listening to the beacons. The Scottish beacon, GB3ANG in IO86mn near Dundee has been perfectly readable for extended periods which is pretty amazing for a station using a 4 element Yagi and 20 watts.
http://www.youtube.com/watch?v=j8TYKrmpfrY
Andrew
G0RVM
Back in the 80’s I received my first amateur radio license, a ‘B’ license as it was back then entitling me to use, if I recall correctly, bands above 30 MHz only. We didn’t have 6m and 4m band allocations then so it meant 2m and 70cms were the bands of choice for me and the majority of other ‘B’ license holders.
So I started with 2m and 70cms SSB and my interest was soon peeked by space communications with Oscar 10 etc. Those early Oscar’s were excellent as, if I recall correctly, they where in elliptical orbits which meant that they appeared to hang in the sky for some time, not shooting overhead as do satellites in lower more circular orbits. Their transponders were just like big SSB repeaters in the sky and I worked all over Europe. Happy days. But working those Oscars was not that easy especially at Acquisition of Satellite (AOS) as they were pretty far from the Earth so a good station was needed. My station grew to a 2m, 9 element crossed Yagi; a 70cms, 19 element crossed Yagi, both circularly polarised; azimuth plus elevation rotators and mast head preamplifiers. The radio was a Yaesu FT-736 which I only sold last year…It was a wonderful radio.
Of course with those antenna’s it was perfectly possible to work terrestrial communications too. I made contacts across the UK and Europe using sporadic E and Tropospheric propagation. Those were exciting times indeed as not only was amateur radio new, to me, but it was such fun learning about different types of propagation, satellite communications and having great fun talking to people.
Ok, so by now some of you will be asking – what is the point of this article? Well, bear with me… I learnt Morse code and in the early 90’s received my ‘A’ license. Soon afterwards the world changed as I started doing radio professionally for a few years. This removed all interest to do amateur radio stuff when I got home from work. Anyhow, time passed and I started to operate on HF talking to people all over the world – it was fascinating – I learn’t lots more.
With solar cycle 24 rapidly fading and with the real possibility that cycle 25 may be no better, probably worse, I’ve been looking back and found myself comparing my V/UHF experiences with those of HF.
My conclusion is that HF is fun, its pretty easy to work stations across the UK, Europe and further afield depending on your station. Take a minute and think about that, especially the ‘depending on your station’ bit. Do you have the space to erect, for example, a 9 element Yagi for the 20m band? I’m seriously impressed if you do 😉 I bet most of us are using simple HF antenna’s and we are constrained by space, interference and the cost of erecting a high-performance HF station. But move on up to VHF and things get so much easier. I bet many of us could erect a 9 element Yagi for the 2m band and mount it several wavelengths above ground too…. Such an antenna will cost a tiny fraction of its HF equivalent; its small, light and easily rotated too. Interference does certainly exist above HF but its nowhere near as bad. But, FM repeaters and modes such as D-Star aside, VHF is dead these days I hear you say? I cannot deny that it is much quieter than in the 80’s and 90’s but its still a happening place… Its perfectly possible to work stations using phone and data modes across the UK and into Europe when propagation is flat. All those exotic data modes are present and in active use too, people are exploiting Tropospheric propagation, meteor scatter, satellite communications, auroral propagation to name a few.
So its back to the future for me, the HF antenna is now down and until I receive my new VHF antenna I’ve elevated one of my original 9 element Yagi’s. Already I’m hearing beacons GB3ANG in Scotland, GB3VHF in Kent and GB3SSS in Cornwall. I even worked an old friend towards London using CW (RST:559) and Olivia with 20 watts. Who says VHF is line-of-sight. 🙂
I guess you realise the message by now…. V/UHF is lots of fun, you can work DX, high-performance stations are much more achievable than on HF and you learn lots. Amateur radio is so much more than HF, FM, repeaters, D-Star etc. So, why not explore our higher bands?
Andrew
G0RVM
