Sunday, 22 June 2014

Legal AM/SSB CB Radio in the UK

Finally after over 30 years of waiting AM and SSB modes in the UK will be legal to use from the 27th June 2014. Ofcom announced this final decision on 17/06/2014 with the following document:
Many people that campaigned for AM CB radio back in the 70's and early 80's have sadly passed away or have moved on to other hobbies such as amateur radio. But there still is hard core CB operators that will take up the new modes and will breath some life into a slowly dying hobby.
The frequency range will be 26.965 to 27.405 MHz on FM/AM/USB/LSB on the band commonly known as Mid/EU/FCC/CEPT. The power output will be the maximum of 4 watts AM/FM and 12 watts pep SSB. Ofcom has put a limit on the amount of effective radiated power (ERP) from the antenna. This means that if the maximum power from the radio is fed into the antenna without losses, than the antenna can't be longer than a 1/2 wave.
But what about CB operators with commonly used 5/8 wave antennas? In reality there's a small loss in the coax cable and the antennas matching coil, so replacing your 5/8ths Sirio would be a silly thing to do. Plus there isn't a huge gain over a 1/2 wave antenna.
Reading forums and talking to people on-air, many see this as an opportunity to use their old classic equipment, mainly imported rigs (radios) designed for the American market. Though this will probably be illegal due to the question mark over these rigs as they may not comply to Euro specifications.
My personal opinion is if the old classic rig has a clean output and has no EMC (electromagnetic compatibility) issues, we might as well use them. They are a part of radio history and better to be heard on-air than sitting in a glass cabinet. Even obsolete 23ch AM rigs could be used again.
Here's an example of an old Johnson Viking designed for the American market from Mark in Essex:
But for those wish to be strictly legal or wanting to purchase a new rig, there are several models on the market:
Albrecht 2990 (Handheld)
Albrecht AE5890
Albrecht AE7500
President Jackson 2
President Grant 2
Also there's the Midland 8001XL if you can source one, and several models from the past that may be legal:
President's Jackson (mk1) ASC, Grant (mk1), George
Superstar 3900 if it has a certificate of conformity stating EN300433.
Will the legalisation of AM/SSB, and with the already legal use of FM on the CEPT band, see the withdrawal of the UK (CB27/81) FM band? Reading Ofcom's documents the UK band will still be available. This is good news as we in the UK have a 80 channel system, giving greater choice to CB users.
I will be on the air the weekend of the 27/28/29 June and see who's on. My location will be in Glastonbury that weekend with the call signs 26CT052 / 26TM552. Catch you on the air!
73 from Dave the Pixie
PS This isn't a guide to legal CB radio in the UK. If you are concerned about the law and the latest legislation, refer to I take no responsibility for your use of non-conforming equipment.

Sunday, 19 January 2014

Adventures on 4m (70 MHz) Part 2

Haven't blogged for a while and have been busy doing other stuff. 4 metres is doing well. Recently I managed to pick up a used but in good condition Anytone AT-5189 25 watt mobile rig .

A simple but effective rig with good sounding receive and transmit audio. Programmed in 70.400, 70.425, 70.450 (calling), 70.475 and it scans as well. Kept it for now on these frequencies as the rig is in my van and I wanted to keep it simple. If I want to use another frequency, the Anytone has a VFO mode. Only thing I don't like about it is the short lead on the mic. I will have to extend it!!

There's a small but growing group of us in the West Cornwall area and we operate mainly on 70.475 MHz. I'm using a 1/4 wave antenna on the van, which is a stainless steel whip from a CB antenna and about a metre in length. So far I'm getting good signal reports for the hilly rural terrain of Cornwall compared to 2m (145 MHz) and 70cm (433 MHz) bands. The ground wave performance is very much like 27 MHz CB radio, but without the noise and interference. Another benefit of 4m mobile over 2m and 70cm is the reduced amount of signal fluctuation.

Unfortunately I haven't had any DX opportunities, but this is a new band for me and I'm patient. I do have plans later this year for a portable antenna and a transverter for SSB operation. Roll long the summer :-)

73 de Dave G7OPC

Friday, 17 May 2013

Adventures on 4 Metres (70 MHz) Part 1

In my 20 years of being a radio ham, I have never used 4 metres/70MHz. So I purchased a Wouxun KG-UVD1P 4m/2m dualband 5 watt handheld transceiver from . It has a frequency coverage of 66-88 MHz and 136-174 MHz which makes it ideal for 4m portable work as well as 2 metre (145 MHz) band use, listening to the boats on VHF marine band and it has a FM broadcast receiver as well. So at least if I got nowhere with 4m, I can use it on 2m where most local amateur activity is to be found.

The radio itself is well made for the price, very sensitive on receive with clear audio. Programming the memories is a bit of a pig, but once you understand the designer's logic is quite straight forward. The supplied rubber duck antenna is 29cm (11.5") in length and gives reasonable performance on 2m, but not so well on 4m. This is because a 1/4 wave antenna on 2m is 49cm in length, and 4m is around 105cm in length, compared to the convenience of the rubber duck - a shortened inefficient antenna.

For handportable work, I decided to build a bigger antenna but it needed to work on both bands. The simplest solution was an 100cm telescopic whip mounted on a PL259 plug with a small matching coil inside. A 4-turn coil was made from a piece of enamelled wire which was wound along a 4mm diameter screwdriver. The coil was soldered into the pin of the PL259 and the other end to the telescopic whip. I clamped the whip carefully into a bench vice and filled the PL259 with Aradite epoxy resin and allowed it to set. The antenna at 100 cms in length was good for 4m. Reducing the length to 45cm on 2m, and it even works on 70cm (433 MHz) and PMR-446 MHz with a low SWR when precisely adjusted. On this years May Bank Holiday Weekend I had the opportunately to use the Wouxun and the telescopic antenna from Cox Tor on Dartmoor to the Redruth area in Cornwall speaking to Norman G4USB and Brian G4KAW, which is approximately 60miles on groundwave propagation.

For a homebase antenna, I have stuck up a 1/2 wave "Bazooka" which details of its construction is discussed here on the Charlie Tango DX Group Radio Forum:

That's it for now. More Adventures on 4 Metres to come........

73 de Dave G7OPC

Sunday, 7 October 2012

PMR446 Parrot Repeater

This summer I visited Ireland on holiday. Part of the fun of going over was to set up a simplex "parrot" repeater on the PMR 446 MHz band in the Galway / Clare area with local radio enthusiast Luke 29ER139.

The principle of the simplex repeater is that it receives a transmission, digitally records it and then automatically retransmits that recorded message. Hence it's commonly described term: the parrot repeater. The useful thing about the simplex repeater is that it can be connected to most transceivers on a single frequency. No need for a duplex (dual frequency) facility. By recording and repeating a transmitted message with a repeater station set up on high ground, communication range can be extended. The only problem with this system is that you have to wait for the retransmission to finish to be able to reply. There is a time limit with the parrot, usually no longer than 30 seconds.

The following YouTube video shows now a simplex repeater works.


Very popular this days are the Pan-European licence-exempt PMR446 walkie talkies. Being low power devices the range is small, several 100 metres in built up areas to several kms in clear countryside. Having a simplex repeater allows these walkie talkies range to be extended over a greater area. Luke and I decided this was the best cost effective repeater system for his local area.

A Radio-Tone simplex repeater controller (SRC) was purchased online from eBay and sent over from Hongkong and taken over to Ireland. Luke supplied a Puxing 777 handheld 5 watt UHF transceiver and is easy to set up with the SRC. A lead acid 12 volt battery was chosen to power the repeater with a trickle charger off the mains electricity. The SRC has an internal rechargeable battery and that was removed, as the the unit can run on 12 volts. Unfortunately the manufacturers of the 777 doesn't recommend voltages higher than 8 volts as it uses a 7.2 volt battery pack. So I had to make a 7.2 volt regulator using kitchen table technology. Going through Luke's components and scrape pile of old radios, I managed to build a L200C regulator circuit. This was all mounted in a plastic tub ready for action. For an aerial system we decided upon a Nagoya NL770 mobile antenna, as it's a 5/8wave over 5/8wave colinear with some dB gain, light weight, and has a low SWR on 446 MHz.

Testing the repeater on a dummy load. To the left is the regulator,
right is the 777 and at the bottom is the SRC.
The homebrew L200 regulator circuit built inside a CB pre-amp box

The next day we drove to a nearby high spot which is about 900 feet asl to install the repeater in a shed (with permission of course). We fixed the antenna on a plastic drainpipe and mounted it on top of the shed. Connected several metres of mini RG8 coax cable between the repeater and antenna, and did the final checks. All was working fine.

Luke installing the antenna

Overall the repeater has a good and reliable 20 plus km range, through quite a hilly area with a wide coverage of forestry. We were pleased with the range as UHF signals don't work well in wooded areas. So now the locals on the border areas of county's Clare and Galway a free community repeater on PMR ch 7 no tone (no ctcss at the moment).

I recently spoke on the phone to Luke the "repeater manager", and it's still working. The only problem is that the cheaper type of PMR walkie talkies have poor transmit audio and don't reproduce well when repeated. Next time I'm visiting Ireland, I'll check the audio settings, replace the coax with a higher quality coax as mini RG8 is a bit lossy at UHF, replace the antenna with a higher gain model, and programme the tone squelch if there has been any abuse.

Monday, 4 June 2012

Binky Goes Off-Grid

Binky, an old friend of mine who lives in a nice wooden cabin on a farm, contacted me recently needing help putting together her off-grid alternative energy system. Now for many people having an alternative energy system has become the latest middle class hobby to save the planet (said tongue-in-cheek). But for Binky it's essential as she has no mains electricity. I went down to see her and she presented me with a:

* 6 amp solar panel (from the USA but can't remember the manufacturer)

* a very fancy all singing, all dancing charge controller unit (Schneider C40) to prevent overcharging

* an amazing bank of industrial 70 Amp hour nicad cells that was she purchased secondhand (Alcad LC-70). The nicad battery consists of 10 x 1.2 volt cells linked together to provide 12 volts.

* a small cheapie (but very useful) multimeter to check the voltage of the battery.

My brief was to put it all together in a safe and efficient manner. For a start the voltage of the system is 12 volts, which means thick cabling as there is potentially high currents involved and to avoid power losses. Luckily Binky is quite a low power user. She mainly wishes to power a small DAB** digital radio and a lighting circuit, but with plenty of room for future expansion. Fuses need to be added and a meaty diode in-line with the solar panel to prevent power feeding back down.

"Mains" style switch/fuse boxes was used with 13 amp fuses, between the battery, charge controller and solar panel. Used "cooker" cable to wire it all up. All the connections are through a large "choc" block, which also supports the diode. All of this was bolted onto a wooden panel to be mounted on the wall. At the moment all power distribution is via automotive "cigar lighter" connectors. Not the best connectors in the world, but useful for now.

As the system evolves I will update you all on its progress.

Best wishes from Dave the Pixie

**Digital Audio Broadcasting

Sunday, 6 May 2012

21 to 30 MHz Mobile/Portable Antenna

A few months ago I purchased at a radio rally a Sharman Multicom 40M band mobile antenna on a whim. Wasn't really into using it, so decided to convert it to other bands. Initially it was going to have a frequency range of 24.9 to 29.7 MHz to cover the 12M & 10M amateur bands with 11m CB. It was going to have a base loaded coil with 5 taps to select the bands required. As I was experimenting a quick change of mind occurred and it was decided to add the 15M (21 MHz) amateur band.

The antenna consists of two sections. The bottom half which is a fibre glass tube with the loading coil and at its base has a standard 3/8" UNF thread, and the top half which is a stainless steel whip. Two grub screws hold in the whip and allows adjustment for tuning. As there is plenty of enamelled wire (22swg) in the bottom section, this can be reused to wind loading coils for other frequencies.

First stage of conversion is to carefully cut off the heat shrink plastic off the the lower section. Cut or desolder the enamelled wire from the base. Unwind the wire so it is straight and parallel to the bottom section, down to the base with the 3/8" thread and cut. Put aside the surplus wire for later.

Glue 5 bolts 40mm apart at the bottom of the bottom section, 10mm above the antenna base. These bolts will be used as taps for band selection on the loading coil. Araldite epoxy resin and 5mm diameter brass bolts was used.

On the highest bolt (from the base) connect the wire. This is the 28/29 MHz tap. You can solder or use nuts and washers to make this connection. Whatever method, don't forget to scrape the enamel off the wire otherwise you will have a bad connection!

Between the 28/29 MHz tap and the 27 MHz tap is 3 turns of wire.

Between the 27 MHz and the 26 MHz tap is 3 turns of wire.

Between the 26 MHz tap and the 25 MHz tap is 2 turns of wire.

Between the 25 MHz tap and the 21 MHz tap is 11 turns of wire.

Solder a short wire link from the antenna base and connect to the 21 MHz tap.

I wanted the whip to slide inside the antenna for storage. So the two grub screws on the top of the bottom section was removed to use a 4mm thumbscrew or similar. Unfortunately my local hardware store didn't have a thumbscrew, so I used a 4mm bolt bent into a L shape. I inserted 50mm (2 inches) of the the upper whip and tightened up the L bolt, to allow for future adjustments. Tape or use heat shrink plastic over the wire along the bottom section to the 28 MHz tap.

The antenna was tested on top of my van using a Sirio SO239 body mount with a 3/8" to SO239 adapter. As an experimental antenna, I used thin strips of tape to hold the windings in place. Wire jumper made from 160mm of flex with crimp connectors both ends. Connect one end of the jumper to the 21 MHz tap with a wing nut, and use the other end to connect to select the other taps, with a wing nut. For 21 MHz, remove the jumper wire.

Minor adjustments were made to the windings to improve the SWR. When you are happy with the SWR, glue or use self-amalagamating tape over the windings.

The SWR bandwidth is nice and wide. Measurements taken with a MFJ 269 Antenna Analyser which I recently purchased from Roy at

10M Section
30.0 = 1.5
29.5 = 1.4
29.0 = 1.3
28.5 = 1.3
28.0 = 1.5

CB27 Section
28.0 = 1.3
27.5 = 1.2
27.0 = 1.3
26.5 = 1.5

CB26 Section
26.5 = 1.3
26.0 = 1.2
25.5 = 1.3

12M Section
25.0 = 1.2
24.5 = 1.4

15M Section
21.5 = 1.1
21.0 = 1.1

As you can see, no need for an ATU (antenna matcher)!

Even though my original intention was to use this antenna static mobile, it could be used for portable work, backpacking, balconies etc. You will have to use a suitable groundplane. I would suggest three wires connected together; 3.40 metres for 21 MHz, 2.85 metres for 25MHz and 2.45 metres for 29 MHz. Better mention that I haven't tried this yet and the antenna may need adjusting.

With hindsight, the use of brass bolts wasn't necessary but looks impressive. A neater way of tapping the loading coil for the required band would be using banana plugs and sockets. Especially better for backpacking.

73's from Dave the Pixie, G7OPC.

Sunday, 1 April 2012

Buying Old and New Equipment

For the radio hobbyist buying equipment, there is often a dilemma - do you buy old gear with a good reputation, or new gear untouched out of the box? Old stuff generally is well built, chucky with a feeling of nostalgia, but can be unreliable and difficult to find spare parts. New stuff has a warranty, usually smaller and more compact, and offer an array of facilities that would be science fiction 30 years ago. Unfortunately the downside of modern gear is minimisation causing difficulties in repair, and lead-free solder is unreliable and harder to work with.

One problem if you buy old or new is finding a competent service technician to repair your equipment, which are becoming few and far between is this disposable culture.  Younger people prefer to deal with computers than get involved in radio - many of which don't even know that 2-way radio even exists.

Using the CB/freebanding radio world as an example. Most 10/11 metre modern "export" multimode rigs are just junk. Poor quality control, bad alignment, and a lot of frequency instability for modern standards. If someone is a keen on freebanding, it would be better to buy a HF amateur rig that has been widebanded.

A more sensible approach is to buy equipment that does the job, whether old or new. Flexibility in choice rather than going for the latest bells and whistles. Better to buy gear that can be written off in a few years. If it costs an arm and a leg may be you are beyond your budget. Another approach is to use modern up-to-date gear for every day operating and use the old rigs for that occasional blast of nostalgia. A bit like having a modern hatchback to get to work and back, but in the weekend polishing your 1970's classic car, giving it a good rev up and a spin down the motorway.

 Good examples for secondhand purchase:

* Big old meaty 20 to 30 amp linear regulated power supplies
* Old 2m/70cm rigs that don't have CTCSS (buy a generic ctcss encoder board to upgrade them)
* Old skool Uniden SSB CB radios (if you have a good "rig doctor" to maintain them)
* Antennas that haven't had much use

One thing that should always be purchased new is coaxial cable. Water slowly enters and corrodes down through the cable.

The following video is a tongue and cheek reflection of the combination of old and new stuff:

 73's from Dave the Pixie