All about CB radio

[SiriusHardware]

Originally Posted by G0HZU_JMR

The PCMA board is also listed amongst the Cybernet radios in the Cybernet Export Service Manual...

Yes, that's where I was looking at the diagram just now.

Originally Posted by G0HZU_JMR

...looks like a classic Cybernet export schematic so it would have to be a deliberate copy/fake if it wasn't Cybernet.

...I agree.

[SiriusHardware]

More from the vault: A couple of small handhelds. Well, one small handheld. One not so small.

1) Generic oversized handheld, 2 channel, CB / 27 / 81 UK. Exact date unknown, possibly late 1980s. Badged 'Sonic' but seen with many different brand names.

This is one of a pair a work colleague and I occasionally used for on-site comms when we were checking or tracing problems in large CCTV systems, etc. Like many radios of the period it has 'Military' styling making it look (vaguely) like a metal bodied Vietnam-era military field telephone or walkie-talkie, although of course this is made from plastic. Its rather toy-like appearance might lead you to suspect that it must be a four-transistor set with a super-regenerative receiver, but in fact it is a 'proper' set with a crystal controlled single conversion superhet receiver and a multistage transmitter, probably about 100mW, since it is powered by a 9V PP3.

2) Harvard Zero-Two-Zero, 2 channel, late 1981 or early 1982. CB/27/81, UK

This was among the first flurry of sets that I bought in the immediate aftermath of legalisation. Oddly, I only ever bought the one. Virtually identical in specification to the 'Envoy' but a much neater and more compact set. I routinely worked distances of several miles back to base stations or mobiles using this set. Unfortunately the aerial is non-original and slightly shorter than the original: The original one was accidentally snapped by someone when the set was just a few weeks old.

The last picture shows the comparative sizes of the two sets.

[Reelman]

Originally Posted by SiriusHardware

Colt 355, CB/27/81 UK version
.....I have never seen any other example of this model.

Well I also have one bought in Leamington Spa in the early 80s. Liked it because it was so small.

I have a soft spot for the Fidelity 1000, it was my first rig (did we call them that?) and then passed it on to my father. The squelch control was "softer" than some other sets and so provided a less tiring listening experience.

Have listened on the European frequencies quite recently and heard absolutely nobody, how times have changed....

Peter

[Biggles]

Just found two Fidelity FM2000's in the shed. I use my Chinese Anytone AT5555 for general 10/11 metre monitoring nowadays so they haven't seen any use for quite a few years. Regarding HGV and 4x4 vehicles, I've never quite worked out why a lot of them have two CB antennas. Have they two separate sets installed or is it just for "added effect"? As I mentioned earlier, the local quarry and associated wagons use CB a lot near me. They give instructions to the loader and warn of their approach for a load. The massive base antenna is mounted right on top of the highest quarry structure where the controller sits and must have a decent range. Also most farm tractors round here seem to have sets fitted, although one or two have their own private licensed radio channels. Most of the time I expect farmers need a couple of miles range maximum.

[SiriusHardware]

Originally Posted by Reelman

Colt 355, CB/27/81 UK version... I also have one bought in Leamington Spa in the early 80s. Liked it because it was so small.

I stand amazed! That makes two that I know about.

Originally Posted by Reelman

Have listened on the European frequencies quite recently and heard absolutely nobody, how times have changed....

UK activity on the EU frequencies was never particularly high, but if you want to hear overseas traffic there you need only wait for late May through to August. You'll hear something from Europe on those frequencies during daylight hours on most days during that period.

[Biggles]

I recently read in one of the radio mags that there is a European CB net every Sunday afternoon on 27.93125MHzFM after 2PM, but I must admit have never bothered monitored it yet. May be worth a listen.

[SiriusHardware]

Originally Posted by Biggles

Have they two separate sets installed or is it just for "added effect"

It wasn't until quite late on in the history of UK CB that the CEPT band and the 27/81 band became available to buy in one legal set. Originally CEPT in the UK had its own technical specification which was distinct from the specification of 27/81, so it wasn't possible at first to buy both legal bands in one legal set. You had to have one set for each band.

If they are using 'historic' sets they might have one 27/81 set and one CEPT set, requiring one aerial each. However most 'modern' specific-purpose users are more likely to be using newer sets with CEPT and 27/81 in one box.

Another possibility is that the aerials are co-phased - you used to be able to buy ready made up harnesses for co-phasing a pair of aerials and the intended effect was to concentrate the radiation / receiving pattern to the front and rear of the vehicle, which made sense if your contacts were mainly going to be ahead of you or behind you on a long straight road.

For it to work properly the two aerials needed to be a minimum fraction of a wavelength apart, which was achievable if they were mounted on the wing mirrors of a huge American Mack or Peterbilt truck. I'm not sure that it could be achieved on a British or European vehicle.

Of course, they might just like having all those aerials swishing about. There may not even be radios on the end of any of them.

[Techman]

When I was logged in earlier I typed out a very long and descriptive post about all the history and goings on of CB radio in this area. Unfortunately, I 'clicked' the wrong thing by mistake and lost the whole lot before posting Moral of the story, always 'select all and copy' every so often just in case of an accident - which is what I normally do, but not this time. I'm too tired to type it all out again now but I'll get round to posting all the other stuff again during the next day or so, hopefully

Anyway, some pictures for now of some of my very early 'kit' and also a Colonel FR360 (same as the WKS1001) which I couldn't resist buying from a local ham rally last Sunday for a tenner. It does actually work, although I really bought it for spares as it has an original 2SC1969 and 2SC1909 (should really be a 2166 or 2078), it depends whether I can bring myself to break it. It has that strange band set up with the normal 'old', now legal 40 channel low band, but with a strange overlapping mid band that goes from something like channel 36 low band to channel 21 UK 27/81, the high band is in the top half of 28 MHz. It's AM and SSB only, so has limited use.

Pictures:-

[SiriusHardware]

Originally Posted by Biggles

I recently read in one of the radio mags that there is a European CB net every Sunday afternoon on 27.93125MHz FM after 2PM, but I must admit have never bothered monitored it yet. May be worth a listen.

(That's channel 34 (CB / 27 / 81)).

[SiriusHardware]

Originally Posted by Techman

A Colonel FR360 (same as the WKS1001)... it depends whether I can bring myself to break it.

As it has survived intact and working for this long I would be inclined, personally, to keep it that way. It would be a pity to break it up now for two transistors. It would be different if it was a non-working hulk. The frequency readout was (then) way ahead of its time, which makes it an unusually interesting, quite collectable set for the period.

You may not know, but just in the last year, AM and SSB have become legal modes Europe-wide (including UK) on the 40 CEPT channels -only-, although of course you can only transmit on those modes / those frequencies on a type-approved set. At least wait for the sporadic 'E' season and have a listen around on it then?

[Techman]

Hi, yes, thanks, I was aware of the new legal AM and SSB allocation on the old lower 40 block and do have other kit that will operate on those modes and frequencies.

In reality, I'll probably keep the Colonel in one piece. The frequency readout is a little bit dodgy, but I was told this by the person selling it. It's a little off frequency to the negative, but this can easily be adjusted - I think it's actually a pot rather than trimmers on this model.

I've read the other interesting thread (now closed) in the wanted section and will add a link to it for completeness:-
https://www.vintage-radio.net/forum/...d.php?t=133260

There's also some interesting talk about the non-availability and rareness of the 2SC1969 and MRF477 RF output transistors in another thread, although some obvious 'fakes' of the 1969 have come my way recently which seem to work very well - so far. A link to this thread:-
https://www.vintage-radio.net/forum/...d.php?t=131872

[electronicskip]

Originally Posted by Biggles

I recently read in one of the radio mags that there is a European CB net every Sunday afternoon on 27.93125MHzFM after 2PM, but I must admit have never bothered monitored it yet. May be worth a listen.

We have a local CB net every Sunday afternoon around here at about 3pm. (Gloucestershire/Worcestershire/Hereford etc)

[Techman]

The baby Cybernet Beta 1000 (135 chassis) I pictured previously may look mint and boxed, but it actually had a lot of use mobile in my van and eventually stopped working years ago. That's a good tip about those trimmers around the VCO mentioned in a post earlier in the thread and something I'll have a look at when I decide to fix it. I've certainly had to replace a number of ceramic trimmers that have gone o/c in the 059 chassis radios in the past.

Below is a picture of the innards of the 135 chassis Cybernet. Also, from my parts box, is shown the remains of a gutted Rotel 220 (134 chassis) and another chassis from a 'Gecol' radio that's been gutted by me for parts, but they still show the basic idea of the chassis. I thought I had the gutted remains of a Fidelity 1000, but I seem to have lost it somewhere. I've also pictured a Barracuda that was given to me by my next door neighbour several years ago. He got it for his boat, but never used it. It had its instruction book, but sadly not the box. This radio has a Cybernet chassis, although I've never removed the covers to look. I think these were sold by Halfords as my brother bought one brand new from there back in the day. He also bought a new Rotel 220 and I think he still has this one in its box in his loft. You may notice that the Barracuda has a small 'gel battery' strapped to the bottom of it with cable ties, this is because I've been using it 'portable' to track down 'local interference' :-

[SiriusHardware]

If you're 'fox hunting' you will get to the point where you are close to the target and you have full scale indication on the meter while you may still be 300 metres from your quarry, making the source difficult to narrow down further.

At that point, if you have or can lay hands on a high end scanner with an S-Meter (Yupiteru 7000 or something like that) try tuning that to exactly 3 times the frequency of interest, and you may be able to hear the much weaker harmonic signal from the transmitter. That will allow you to home in very close.

The trimmer which fails in the 135 chassis is CT1, which is switched into circuit on TX by Q2 and pulls the VCO free-run frequency down from RX-10.7Mhz (~17Mhz) to about half the TX frequency (~13.8MHz) in transmit mode.

I have no idea why it caused so much trouble on the 135 when the equivalent trimmer in the 134 rarely gave trouble. Maybe Cybernet just sourced them from another, inferior supplier when they were building the 135s.

Rather oddly, my 1000 diagram doesn't state the value of CT1 and shows the fixed parallel capacitor as 22pf with an asterisk next it, meaning 'this component might vary'.

CT1 in the 134 is 20pf, and has a 15pf capacitor across it.

Originally Posted by Techman

I thought I had the gutted remains of a Fidelity 1000, but I seem to have lost it somewhere..

Lucky you.

[SiriusHardware]

..More from the archives. Just to vary it a bit, here are some... manuals... for which I have the radios.

1) Binatone 5-Star - 1981 - needs no introduction, I'm sure. Bought from Rumbelows on 2nd November 1981. Heavily used during the early years and still my favourite individual radio, in part because I had it from day one of Legal CB. It gets a run out every now and then.

2) Realistic (Tandy) TRC1001, 40 channel, 4W CB / 27 / 81 UK handheld, bought late 1981. I had this on pre-order from my local Tandy for several weeks before November 2nd but it didn't turn up until 2-3 weeks after that date. I absolutely loved this radio and often went cycle-mobile with it. It has connectivity for an external microphone, speaker, aerial, power, so it was a very versatile radio. I used it as a throw-in mobile in vehicles which weren't mine (in the days when vehicles had level dashboards which you could put things on). I had to take it apart a couple of years ago to de-crackle the volume and squelch pots, but it still works. The radio itself is almost a foot tall and the aerial is enormous, around 5-6 feet fully extended. The telescopic aerial on the original USA / AM version of these had a centre loading coil, but the UK spec didn't allow centre loaded aerials so this version just had a plain whip with a heavy wire wound matching coil inside, between the transmitter output and the antenna.

3) Realistic (Tandy) TRC1002, 2 channels, 1.5W, CB / 27 / 81 UK, date unknown. Works well but ridiculously oversized and clunky for its specification, with obviously US military inspired styling. This radio has been crystalled and retuned for 2 frequencies in the FM section of the amateur 10 metre band since the mid nineties, although I still have the original crystals and it would be straightforward to restore it - I might eventually do that.

4) Midland 77-095, CB / 27/ 81, UK, late 1980s / early 1990s - probably the least used and least loved of all of my CB radios. I bought this when I went over to meet friends in the Lake District and discovered I had forgotten to take a CB, so I made an emergency visit to Penrith and bought the cheapest CB radio available - this radio. No meter, and nothing very much else that is nice about it. It probably has less than 10 hours on the clock and is still boxed. One thing I can say in its favour: It is very compact, very neat.

[Jonster]

The last CB I had was Midland 77-095 in my Lightweight Land Rover, it actually worked quite well, and mounted neatly onto the bulkhead footwell.

The one I wish I had kept was a Maxcom 30E, this was one of the first radios to have a crystal filter fitted instead of a ceramic type in the 10.7MHz IF stage, it was very narrow band and gave a harsh receive audio, I changed it for a Golledge one which was slightly wider and less lossy which made a big improvement, along with some other mods it was usable with weak signals less than a microvolt. I also added an EEPROM piggy back board to enable it to be used on the CEPT channels as well, selected by the HI/LO tone switch.

[Techman]

A couple of mentions of the Midland 77-095. I guess these are probably electrically similar to the Midland 77-805UK as used in the Midland Porta-Pack?

I have a Midland Porta-Pack, dated on the rear as manufactured in June 1990, that I bought probably sometime around 15 years ago for a tenner with a faulty handset lead. I originally did a bit of a bodge by cutting into the lead where I had identified the break just before the handset itself and spliced the audio wire and taped it back up. However, although all connections were now perfect, any movement of the cable produced a 'rustling' sound on TX audio. So I eventually had to bite the bullet and cut the bad section of the cable off, straighten out a couple of 'curls' with steam and shorten the cable by around six inches.

The midland Porta-Pack 77-805 is a wonderful little radio (rig) as in my opinion, the radio itself without its 'pack' makes a perfect set to run in the car. When I made a bit of a comeback several years ago, I popped up a small mobile aerial on the house. I soon got moaned at because people couldn't hear me properly, particularly with all the digital hash that most have to contend with much of the time. So I was soon offered a proper homebase 'Silver Rod' antenna by a generous operator, so long as I came over to pick it up. I was given the rough area and popped the Midland on the passenger seat of the car with its centre loaded telescopic aerial sticking up through the partly open sun roof. This is obviously very inefficient, but was perfect for when I got into the chaps village as he was able to direct me in to his address. I used the radio several more times for this sort of purpose to pick up other goodies! As well as the Silver Rod aerial, I was given some other bits and pieces including an old mag-mount which needed re-wiring. I now use this mount on the car, with the aerial that I used to use on the house and the little Midland with a wrap of cardboard round it for protection just shoved down the inside of the passenger seat and plugged into the fag lighter socket. I can't believe how well this set works in the car, with full bodied, loud TX audio output - so I'm told. I call the microphone a 'handset' as it's both the microphone and the speaker in one unit, so there's none of this mucking about with extension speakers due to the radio speaker either pointing down at the floor or obscured as it would be the way I'm using the set at the moment. It doesn't actually have a normal mic insert but uses a small transistor radio type speaker with a matching transformer to do both jobs in the handset. As we know, a loud speaker can make a very good microphone, and I think this is probably why the audio is so full bodied on this particular radio.

As for the Silver Rod antenna, it was just missing its 'U' bolts, but I had some that fitted and I popped it on a pole and it worked extremely well. However, I've taken it down now as it was just too 'visible' and I now just have a wire up in a tall tree with a choke wound on a bit of pipe and it works well enough for what I need - and I wish I'd done it this way in the first place.

Below are pictures of the Midland, as well as one of the opened up handset. I've never had the covers off the radio itself, and it doesn't look as though anyone else has, so don't know what chassis it uses. It's intended to run on 'AA' cells, but as you can see, I'd been running it from a gel battery as I've got a few of them. These sets, although portable, are not a lot of good for 'tracking' as there's no actual 'S' meter, just a line of red LEDs. They are a nice little set to stand on the coffee table in the evening with the telescopic aerial mounted on the rear bracket to listen to the 'locals' - should you want to do this, that is...pictures:-

[SiriusHardware]

Originally Posted by Techman

A couple of mentions of the Midland 77-095. I guess these are probably electrically similar to the Midland 77-805UK as used in the Midland Porta-Pack?

No, the 77-095 is the most basic radio you can imagine, with no meter at all. It has the merit of being small and neat. It also has digital channel up/down buttons rather than a rotary channel switch and although I don't like that either, I did consider adding a little circuit to make it scan by electronically blipping the 'up' button 5-6 times a second, stopping if something activated the squelch. No other radio that I owned would have lent itself to being modified to scan so easily, and none of my other radios could scan. I never got around to it though, and not long afterwards, scanning became more or less standard on most radios arriving on the market.

Your 77-805 is virtually the same radio as the Midland 77-104 mobile which was available in both CEPT (PR 27 GB) and 27/81 versions (see post #61 of this thread, images 3-5 for the CEPT version).

A couple of friends of mine had the 27/81 Porta-Pack variant like yours, with the centre loaded telescopic whip. They used it a lot in its unique portable configuration.

I never liked digital four-LED meters but they tended to be a feature on the smallest radios where there just wasn't room behind the front panel for the standard moving-coil edge meter. I would have preferred ten smaller LEDs.

[Techman]

You're right, I see it does look very similar to the 77-104.

These little 'rigs' are ideal for 'in-car' use due to their small size, hence why I originally bought that Cybernet Beta 1000. I've no particular use for the Beta 1000 these days, but I must take time out sometime to investigate the fault. I can't remember exactly what went wrong with it other than it wasn't a simple 'run of the mill' fault, so it may be VCO related as you describe, also it has the green readout missing segments problem.

Something I perhaps didn't make clear to other readers is that the Midland Porta-Pack radio unit itself, does not contain a loudspeaker in its case whatsoever, but just uses the handset as the speaker. There is a extension speaker socket on the rear and I would guess that this disconnects the audio to the handset speaker when a jack is inserted into this socket, although I've never tried it.

[SiriusHardware]

The Porta-Pack is obviously designed to be used placed on a flat surface with its telescopic aerial screwed into the stud mount on the rear, pointing bolt upright.

Configured this way, it wasn't practical to use a downward firing base mounted speaker like you'd get in the normal mobile version - the speaker would be gagged by whatever surface the radio was standing on - so they moved the speaker out to the speaker / microphone instead.