Since the advent of the home computer radio amateurs have explored the possibilities of using them in their shacks, and as computer technology and software have developed it has allowed more amateurs to be able to use a computer even if it is just for logging or using the internet to look up call signs on QRZ.com.
The Single Board Computer or SBC which as the name suggests has all the necessary components mounted on a single board whereas on a desk top computer the various components are attached to a central circuit board via cables.
There are a number of SBC’s available but the Raspberry Pi is probably the best known and I would regard it as a pioneer in the field of SBC’s.
Since its release in 2012 makers and hackers have taken up the use of the Raspberry Pi in a big way and use it in all manner of smart tech projects and so have radio amateurs. There is a lot of support out there for this SBC and in recent years there have been more and more articles in Amateur Radio magazines here in the UK and abroad relating to amateur radio applications using a Raspberry Pi.
So what is the Raspberry Pi ?
First and foremost, the Raspberry Pi is a product produced to be a fairly cheap way for children to get involved in computing and programming either through education in schools or for use at home. Initially the target cost of a Raspberry Pi was around the £30 mark. Despite being made to what you might consider to be a tight budget the Raspberry Pi uses the best components available at that particular time of manufacture.
The previous model the Pi 3B+ is still available and costs around £34 as well, this model is attractive as an old Android phone charger can generally be used to power it and it has a full size HDMI connector both of which reduce the costs slightly as most people the relevant cables or can normally acquire them off friends or family.
Due to its cheap price several of these little computers can be used at once for various radio applications. Consider if you ran two or three separate computers/laptops in your shack then the space required let alone the cost involved would be prohibitive for most people.
The Raspberry Pi does not come with an operating system loaded onto the board so in order to use it you have to load an operating system onto a micro SD card which then plugs into the appropriate slot on the Pi. The Raspberry Pi website has various operating systems that are available to download and when it comes to using the computer for amateur radio purposes then fortunately there are amateurs out there who have written software which is freely available to use.
Amateur Radio Uses for SBC’s
About three years ago I bought myself an SDRplay software defined radio. There are various software downloads available for the SDRplay which are supported by Windows, Mac, Linux etc. and one of the computers listed that is supported with compatible software is the Raspberry Pi.
For their cost and size these little computers are great fun to use and are a very cost-effective way of using a computer in the shack and I can potentially use several of these little computers at the same time for ham radio.
73’s Graham M0GAE
International Lighthouse and Lightship Weekend 17/8/19 – 18/8/19.
The Old Low Light
The Old Low Light is a Grade 2 listed building, the oldest surviving, occupied building on North Shields Fish Quay. It began life as a lighthouse, belonging to Trinity House of Newcastle upon Tyne and was enclosed by Clifford’s Fort in 1672. In the early 19th century, it was converted into an Almshouse and during the 20th century was used as a training establishment for the Deep Sea Fisheries Association and later the Maritime Volunteer Service. It stands within the Fish Quay Conservation Area, is owned by North Tyneside Council and leased to Tyne and Wear Building Preservation Trust.
For more information regarding the Old Low Light have a look at their web page; http://oldlowlight.co.uk/
With some of the preliminary work done the previous day several members of the club were at the Old Low Light, North Shields early on Saturday morning to complete the final set up of the radios and antennas. Two stations were set up on Saturday morning with FT8 and CW kicking the day off.
The event has generated a lot of interest and interaction from the public and two new potential club members, we have spent time showing people how the stations set ups work and have shown them the various modes available. Conditions not good at our location today but the interaction and interest from the public has been brilliant, we have also had a couple of old ex members turn up to say hello, Terry, Rick and Tom.
Glen, Graham and Tony were back at the Old Low Light early the following morning and put the antennas back up to start day two. FT8 was up and running with contacts being made from the off, listening on SSB there were a few stations being heard but not many.
The weekend was hard work from a radio perspective, perhaps this was down to conditions or was there interference in the premises causing problems for us, we need to go back and do some checking.
From the point of view of the Low Lights it was considered a great success and they enjoyed having us at the premises and we enjoyed the welcome that we received. The interaction with members of the public was also very good with most of them taking time to find out about what we were doing.
73’s Graham M0GAE
Glen G0SBN, Graham M0GAE and Bob M0KLO set off early and drove to Oban to catch the ferry across to Mull, Chris GM3WOJ joined the group driving across from his home in Inverness.
We met in the car park of Aldi where the last of the food supplies were bought and we then headed to the ferry terminal to await the 2 o’clock ferry to Mull, the ferry was about 20 minutes late but we were soon on our way and driving down to The Old Ferry house at Grass Point.
The cars were emptied of foodstuffs that were packed away and rooms were sorted out before the antennas were constructed. It was decided to work until about 7 o’clock when we would have our evening meal and after that the stations would be put together.
In the time given we managed to put up five antennas, a multi-band doublet and four vertical ground plane antennas for 80, 40, 30 and 20 metres which was good going, the weather was sunny and warm which helped and there was a good breeze which helped to keep the midges at bay, it was decided to put the remaining antennas up the next day.
The stations were set up and we were operational with any glitches with set ups and computer connections sorted out. It had been a long day so everyone drifted off to bed between midnight and 0230hrs.
Saturday 18th May 2019
It was expected, so it didn’t come as any surprise when we awoke to rain today, but we didn’t expect it to be as cold as it was so there was an obvious reluctance to get outside and put up the remaining antennas including the two Hexbeam’s.
The day was spent operating and sorting out one or two glitches with computer connections on one station. 80, 40, 30 and 20 metres were the main operating frequencies for today with FT8, SSB and CW being the main modes. Around teatime weather conditions did improve and one of the Hexbeam antennas was constructed and the mast for the portable Hexbeam was positioned and guyed in order to get them up and running tomorrow. It is planned to have a go at some satellite operating tomorrow as well.
Sunday 19th May 2019
Cloudy start to the day. The standard and portable Hexbeam antennas were put up today and after a cup of tea and a bacon sandwich more radio operating was the order of the day. There are some more antennas to play around with but again they will have to wait.
Conditions on the bands aren’t brilliant at the moment (or this weekend for that matter) and today was no exception but we are still plugging away with over one and a half thousand (overall) contacts achieved by late evening.
There has been a bit of a gap in activity later today as Graham and Glen took the opportunity to get out and get some fishing in, and yes we did catch some fish which were returned to the sea, also the extended evening meal of steak and chips took up some time because the birthday boy, Graham had brought along some ‘fizzy’ so the relaxed chat around the dining table went on for a while. We did eventually get back to our stations and resumed operating on 80, 40, 30 and 20 metres.
Monday 20th May 2019
Checkout the clubs Facebook page (G0NWM) to see some early morning visitors to the station, a small herd of Highland cows. There were a few anxious moments as they were walking through the guys holding up one of the Hexbeam’s and a couple of the vertical antennas, anyway they were persuaded to move on. Unfortunately any thoughts of a lie in were well and truly dashed this morning. It was back to the radios to get some more contacts as we were just short of 2000 contacts this morning. Radio operations were steady throughout the day but conditions aren’t brilliant and sometimes the noise on the bands becomes too much to be able to operate comfortably.
Tuesday 21st May 2019
Well today started out brighter than it has been for a few days although the wind was fresh at times, it was nice to see sunshine. Conditions were very much up and down again with the tally of QSO’s just over three thousand two hundred in the evening. Today was the day that Graham M0GAE was initiated into FT8 and started to operate in this mode, it was quite difficult for him to decide whether to read a book or make a cup of tea (or do both) while in the process of operating in this mode. Joking aside he did see that it was a good way to see how propagation was working and how the antennas were performing. He also had to agree that contact could be made with stations that we wouldn’t normally be able to speak to due to the kilowatt scrum.
How many radio amateurs does it take to operate a handheld satellite antenna ?
Quite a few it seems, this evening we had a go using a satellite antenna with two people in the house passing information out through the window regarding heading and elevation and two people outside, one holding the antenna and the other passing on the information from the house. It was a bit of a comedy act at times but we did manage to hear a satellite as it passed over and two French amateurs were operating through it. The highlight of our attempt to work satellites as dusk was descending was watching the International Space Station racing across the sky, we couldn’t hear anything coming from it but it was interesting to see.
Wednesday 22nd May 2019
Today started as usual, a bit cloudy and the bands weren’t as good this morning as they were yesterday, we currently have four thousand QSO’s in the log. Contacts were steadily made throughout the day despite it being the worst so far regarding working conditions, FT8 worked well through the day when it was difficult to work on CW or voice. The weather did improve in the afternoon and some of the team went out to see the Otters in the sea. By the end of the day we were just short of five thousand QSO’s.
Thursday 23rd May 2019
Well this is our last full day before we head home tomorrow. Chris was up early and he took us over the five thousand QSO’s for the start of this last day, we will have to take the antennas down this afternoon and start packing the stations away. We ended up taking antennas down and packing the stations away from mid morning, Chris who has commitments tomorrow had to get an afternoon ferry to keep sure he was home in time.
Then there were three.
All the equipment was packed away at a leisurely pace and a relaxing evening was spent chatting and debriefing how the week had gone with regards to what had worked, what hadn’t and how we could improve in the future.
Friday 24th May 2019
Time to head home today.
We set off for the ferry in the morning and boarded on time to get back to the mainland, the journey home was straightforward and uneventful which was good as there weren’t any problems with traffic or roadworks.
I hope you have enjoyed reading about our mini DXpedition to Mull.
73’s Graham M0GAE
Recently I was researching an alternative to Sealed Lead Acid Batteries (SLAB), the cause of this research…back pain. While SLAB’s have performed ok for my car portable use, I was reminded just how heavy a 50AH SLAB is after straining my back putting it back on the shelf. So having seen a number of posts and videos on the Internet about the weight advantage I needed to give alternatives some serious thought.
I suspect like me, many of you will have heard of Lithium batteries but what I hadn’t realised is that there are different types and specifications. I was looking for three things in a new battery; appropriate voltage for amateur radio use (13 to 14 volts), low voltage sag (little voltage drop when under load), and a high number of recharge cycles (reduced cost of ownership).
I hope you agree that Lithium Iron Phosphate (LiFePO4) came out as the most suitable. I was also fortunate that while away on a DX’pedition to the Isle of Barra with Bob (M0KLO) he kindly lent me his KX3 and a small radio model style 13v LiFePO4 4.2AH battery pack to try. It was certainly compact in size, light weight, and an ability to maintain voltage during transmit but the total capacity of 4.2AH I felt was a bit small for what I had in mind.
A battery of about 15AH seemed to be about the size suitable for my needs based on my initial transmit tests with a Yaesu FT-891 “field” radio which suggested about 8 amps on transmit was a good target if I wanted 3 hours of operating time on a single charge. Remember that this is not an exact science as less current is drawn when listening as to transmitting and whether you use CW, Data, or SSB.
A search on the Internet provided a range of options from which I produced a shortlist:
Top or Bottom Balance (YouTube)
How to Bottom Balance a battery pack (YouTube)
To achieve bottom balance I discharged the individual cells to 2.7 volts each and measured the voltage variation between the cells (after a settling period of 24hr) using the ISDT Battery Checker via the balance leads to achieve a variation between cells of only a couple of mV. I then charged the cells to 3.4 volts per cell using the charger's (ISDT) upper storage charge setting of 3.4v with a charge current of 1/10th the pack capacity i.e 15AH divided by 10 = 1.5 Amps. The cell voltage variation at 3.4v across the pack was only 8mV. I found that if the individual cell charge voltage was increased to 3.6v, the cell voltage variation will also increase to 100+ mV. If the charge current is increased for example to 5A then the cell voltage variation will increase at top of charge. This in itself is not a problem, and is predicable, but monitor the voltage to make sure no individual cell goes beyond the 3.6v manufacturer specification.
If the ISDT charger is used to perform a discharge the balance leads are connected and the ISDT unit will not let a cell go below 2.8v. When used with my radio, I use a small voltage monitor connected to the balance leads which cycles continually providing both a pack and individual cell voltages during use. The voltage monitor has an audible alarm set to 2.7v, so if any cell reaches this lower limit an alarm sounds and I stop transmitting and disconnect the battery to prevent further discharge. After use, I charge the pack with a storage charge and store in a dry cool place in my garage.
I hope the article proves useful.
73 Glen G0SBN/P
MOUNTING Having bought my Tank Antenna, I now had to figure out how I was going to mount it. Another club member had a spare mount which he gave me. This consisted of a short metal tube that the Antenna fits into, a metal collet that tightens to secure the Antenna, and all this is mounted onto an insulator which is about three quarters of an inch in diameter and a couple of inches long.
For several weeks I pondered on how I was going to mount the Antenna with or without the mount that I’d been given. While looking at mounting options in my garden one thing that really struck me was that it has a low impact visually. Looking on the internet you will see vertical antennas on the market that are mounted close to ground level so that was an option. There is also a lot said about Stealth Antennas and I thought that it might be a good antenna to mount at the top of the fence and couple it to an auto ATU.
In June 2006 a couple of us from the radio club decided to go out for the day and play radio, it was planned to go to a local farm where we have been lucky to gain permission to use for our various field days. With this planned I worked a bit quicker to sort out a way of mounting the Antenna. Looking at the insulator there is a hole underneath and I wondered if it would sit on top of a section of fishing Pole. It would, but there would be too much flex and it would probably fall to the ground. However, the insulator would fit inside a Swaged pole and also inside a section of fishing pole. I had a couple of spare sections off a fishing pole that was broken as a result of my son using the pole to retrieve his Frisbee out of a tree, he took it apart and put it back together again the wrong way around and trying to sort it out damaged a few sections of the pole, so I now had two spare sections.
I decided to mount the antenna at ground level and cut one of the poles down and fitted the mount inside. I had a Ground Spike from another manufactured Portable Antenna, so I decided to use that, and the Pole fits nicely inside the tube attached to the ground spike. The Antenna was now mounted and supported.
RADIALS The next thing that the Antenna needed was Radials. The Antenna is about 4.9 metres long, so you don’t have to think too hard to work out that it was around a quarter of 20 Metres. Thinking back to a talk given by the Chairman of the club at the time on ground planes and radials I remembered various points discussed and using these principles I made up 12 radials. In the talk given to the club it was mentioned that a good number of radials to use was 120. I couldn’t manage 120 so I decided on 12.
OPERATION On the 8th June 2006 along with other members of the club we went to the Farm to play with our Radios and Antennas. Three of us have Yaesu FT 817’s and we were going to have a QRP day. I took along the Tank antenna, my 817, an SWR meter, an ATU and a small amplifier because my previous attempt at portable QRP operating I didn’t have any success with SSB and I had other people nearby using higher power. To power the entire set up I also took along a Leisure Battery, over the top I know but I wasn’t going to take any chances and if I wasn’t successful with the QRP I was going to use the amplifier, so the extra power would be handy.
I set the Antenna up, connected it to the radio and switched on. Immediately I was receiving good clear strong signals. I hooked up my SWR meter and checked the SWR and it appeared to be spot on, the needle only moved a fraction on the meter. I called the others over and checked the SWR again to show them how good it was (I expected to be fiddling on with the radials for some time to get the SWR right). When the needle hardly moved there was a comment that “It’s broken”. I kept the SWR meter connected to the radio, but I could have actually removed it. I made only made 12 contacts but at a fairly leisurely pace, it was also a social event with plenty of chat. My first contact came after a couple of CQ calls and was with Ian G3PHD in Tilbury, Essex who gave me a 5 & 7. I had one 59 report, a couple of 57 and a lot of 55 reports which when you actually take time to understand the RST system of reporting 5 by 5 reports are perfectly satisfactory. On this first outing I contacted a German station DQ2006S who gave me a 55 report and he obviously found it hard to believe I was running only 5 watts, he kept asking me to confirm I was QRP I confirmed it and he came back to tell me that he was transmitting 500 watts.
At a fun club event on the 15th of July that year a few of us organised a QRP Barbecue come QRP competition. The basic idea was that we would have a day out at the farm, do some operating and have a barbecue. The competition side of events was a wire dipole for 40 metres verses the Tank antenna for 20 metres and Yaesu 817’s as transmitters. Competitors would have a 15-minute slot on each antenna and the person with the most contacts was the winner. There was an adjudicator sitting with each competitor to verify the number of contacts. It was a great day out with fantastic weather, good food (if I do say so myself), good company and overall it was good fun.
DEVELOPMENT Since that first outing and success with my antenna I have made another coax lead with automotive connectors on to tidy up the connection between the coax and the antenna, I have also tidied up the connection with the radials. I have also shortened the section of fishing pole which sits inside the ground spike, it was initially too long and one windy day with it moving about it split the fibreglass tube and fell over. Lowering it takes away that strain on the tubing.
During another day out on the farm in mid-February 2007, my first contact of the day was with PT7CB in Brazil! Wow I was over the moon; this was using the internal batteries on the 817. I also had a contact with CN8PA in Casablanca which was a first for me, so I was also very pleased with that.
Initially the Antenna was not intended to be used solely for QRP and it could certainly be used with more power or as a home base antenna, but I get such a buzz from making a contact using it on QRP that I am now totally hooked, and I would always keep sure that I have a Tank antenna for portable work.
Coming up to date in August 2018 twelve years on from when I first used the antenna.
I still have the antenna; the connections and radials are still working perfectly, and it has been used on many occasions at various power levels. The only further development that I have made with it is a tripod mount for use when I’m on a hard surface and cannot hammer the ground spike into the ground. It is a camera tripod that I was given with the tilt/mounting head on a central pillar that can be raised or lowered in the tripod. I simply took the tilt head off and the section of fishing pole with the antenna mount attached slides over the top of the pillar.
Give the Tank antenna a go, you’ll be very pleased with the results.
Enjoy your radio…
Early in 2018 the club was contacted by artist Sian Hutchings who was in her first year of a masters degree in fine arts at Northumbria University, Newcastle and she wanted some help with a project that was going to come to a head with an event at the Baltic Centre for Contemporary Art in Gateshead on the 15th March.
The club is no stranger to working with artists having previously been involved with the Waygood group and an event called Scatter in the AV08 Festival involving artist Marco Pelijhan again at the Baltic Centre for Contemporary Art in 2008.
Anyway Sian’s project centered around the ‘Voyager Golden Record’ which were two phonograph records that were included aboard both Voyager spacecraft launched in 1977. The records contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for future humans, who may find them. The records are considered as a sort of a time capsule.
Sian wanted to update the recordings stating that she considered the recordings didn’t reflect the way we live in the 21st century and weren’t a true reflection of modern society.
At the meeting Sian outlined her idea to update the golden record and Glen and I told her how we could help which basically meant that we would be able to transmit her recordings, also we would be able to let her see the transmission via an SDR radio receiver but this would all be dependant on whereabouts in the Baltic we would be based in relation to siting antennas. A follow up meeting at the Baltic was arranged and I took a dual band 2m/70cm antenna to show Sian what we might use as Glen thought that 70cm might be a better frequency to use as trying to find another amateur on the band was as likely as finding teeth in a hen and it therefore hopefully wouldn’t cause any disruption to what Sian wanted to do, also it is a frequency that is suited to satellite (space) communication. We also took along a couple of radios to test the suitability of the location. We were to be sited on the first floor and there weren’t a lot of options for feeding coax to the exterior and then onto the roof to feed antennas, it was decided to set up in the outside lobby area and fire the radio signal out of the glass windows running the full height of the building. This would be an easier option as we were right in the heart of the building and all other options quite frankly would have been a nightmare to sort out.