Bernard Nock G4BXD takes a canter through a selection of classic sets from Pye of Cambridge.

One area of the hobby of amateur radio that has diminished quite considerably over recent years is the re-use of ex-commercial equipment, notably sets from the Private Mobile Radio (PMR) industry. Many amateurs active in the 1960s through to the 80s were used to being able to obtain ex-PMR sets at rallies and the like and adapt them for use on the amateur bands, usually in the VHF bands of 4 and 2m and the 70cm UHF band.

There were many firms supplying these radios to industry: Marconi, Motorola, Philips, Dymar and one of the biggest, Pye. Pye radios in their distinctive light blue livery were to be seen in nearly every amateur radio shack in the 1960s and 70s. Many amateurs used them mobile and portable and modified them for roles they were not designed for. Mains powered base stations were also made and available but the quantity of mobile sets was much greater.

These radios provided an easy and cheap source of getting on the bands with the slight drawback that most of the sets needed quartz crystals to set the operating frequency, usually two per channel, one for the receiver and one for the transmitter.

I’d like to illustrate some of the Pye range that many of us broke our teeth on, so to speak, when starting in the hobby. Being mobile radios, most are 12V operated. Some early sets were 6V and adapters, again made by Pye, were produced for 24V vehicles allowing the 12V sets to be installed and operated.

The Ranger

The Pye Ranger introduced the third generation of mobile and fixed station circuit design and evolved into a very large product family that included AM, FM, front mount, short-remote and long-remote mounted versions along with marine equipment. This third-generation design was suitable for all channel spacings between 20kHz and 120kHz, which enabled the company to supply to a wide range of international type approval specifications, including the difficult Canadian market.

The front-mount Ranger was initially designated PTC143, and the series type number designation later changed to PTC2000 for AM and PTC8000 for FM. Each equipment was made up of three individual chassis (receiver, transmitter and PSU), which allowed great flexibility and enabled a matching fixed station equipment to be developed from the common chassis assemblies.

This construction can be more easily seen in the large 25W boot-mount version, Fig. 1, and with the cover removed, Fig. 2. It is interesting to note that as late as 1962 the Ranger and F27AM fixed stations were still being fitted with the old wartime ‘Pye coaxial connectors’. [1]

The boot version sat, as the name suggests, in the boot of the vehicle and a small control box was fitted on or under the dashboard of the vehicle. The dash mount sets, Fig. 3, were fitted inside the car or truck cab, usually under the dashboard.

A boot-mount Ranger was one of the first sets I ever used on the 2m band. Using a QQV-0620 in the output stage and a pair of 6V6 valves in the modulator and with the HT tappings set to their highest level, of course, the set gave me a great signal. On the receive side I did use a nuvistor converter into an HRO set, though. At Christmas time I ran the RF output into a string of fairy lights − not to be recommended with modern sets.

Facts: 1955 – 1963. 25 − 174MHz in nine bands. 5W AM, 15W AM, 25W AM, 10W FM, 25W FM.

The Cambridge

The Pye Cambridge series of front mount, Fig. 4, and boot mounted equipment, again with just a small control box on the dashboard, was a very successful family of fourth generation mixed technology equipment design, with all solid-state receivers and valve transmitters giving RF power outputs of 5, 15, and 25W. Initially designated the PT. D10 AM, the type number was changed to AM10D etc. in 1963.

The higher power Pye Continental FM models BC25 and DC25 were originally given the designation B20FM and D20FM. A UHF remote mount was also created, based on the low-band version but equipped with an extra receive down-converter, which made the receiver a triple superhet.

The transistorised receiver (internals shown in Fig. 5), designed for the Cambridge series, was widely used in both the higher-powered Vanguard family and also in the matching fixed station receivers of the time. The product was replaced by the Westminster series of AM and FM front and boot mounted sets.

The Cambridge proved very popular with amateurs due to its compact size and weight. In addition to the VHF version there was a UHF version with an extra stage in the transmitter and a down converter in front of the usual front end tuner. It was easy to get it working on the amateur bands and many were modified with S-meters being fitted and even VFOs installed to make them tune the whole of the band on receive at least.

Facts: 1961 – 1970. 25 − 174MHz in ten frequency bands. Cambridge, 5-7W AM, 15W FM, Continental, 25W FM.

The Vanguard

The Pye Vanguard was a family of high power remote mount mobiles and was the first of the fourth generation of mobiles that included the Cambridge series. The design used a sealed block LC filter for receiver IF selectivity, as opposed to using distributed interstage bandpass filtering by transformers. See external, Fig. 6, and internal, Fig. 7, views of an AM25B transistor receiver valve transmitter version.

The Vanguard was originally designed to meet a requirement specification issued by the UK Home Office. Pye won the contract with the PT B10AM design, which started production in 1962 and following the success of the product, created a range of standard commercial versions.

The initial PT B10AM and AM25B models were valve designs with transistors used in the audio and power supply circuits. The later AM25T and FM25T versions used the same fully transistorised receivers as the Cambridge AM10/FM10 series. Transmit powers of 20W AM and 60 or 100W FM were available. A 30W UHF FM version, the U30FM, was also produced.

The product family was first introduced as the PT B10AM, PT B25AM, PT B25FM and PT B100FM but was later renamed Vanguard AM25B, AM25T and FM25B. The designation B100FM remained for the 100W version. Various marine variants were introduced as was a fixed station version in a distinctive green cabinet.

The Vanguard product was partly replaced by the Westminster W25FM and W30AM series remote mounts but the Company did not produce high power RF output mobiles again until the 100W PMR2 model of the early 1970s and the 50W M206 of the late 1970s.

The Vanguard was again very popular with amateurs due to its high power output. I used one in the boot of my Mini (the real Mini) in the 1980s and also the transmitter section, cut out of the main chassis, and added an FM modulator when that mode came into amateur use in my shack.

Facts: 1962 – 1970. VHF 25 − 174MHz, UHF 450 − 470MHz. AM25T 20W, FM25B 60W, B100FM 100W.

The Handy Cambridge

The AM10P/FM10P/CM10P Handy Cambridges, Fig. 8, were a family of transportable mobiles constructed using modified boot-mount Cambridge chassis and case parts. AM, FM and FM-Marine versions were available in single- or six-channel configuration. The Marine version had a low/high power switching facility.

A choice of batteries was offered; either a sealed lead-acid battery of 9Ah capacity or nickel-cadmium cells of 6Ah capacity. These were mounted in a detachable container at the base of the unit. An internal speaker was fitted under a lid, Fig. 9, which covered the controls. A quarter-wave fibreglass whip antenna (fitted with a PL239 connector and elbow adaptor) could be mounted on one side of the equipment case and a waterproof microphone clipped onto the other side.

Later models were fitted with a helical whip antenna. The battery charger used was the BC2. Weight: 20lb (9kg) with NiCd battery or 22lb (10kg) with lead-acid battery.

Compared to today’s tiny Chinese handhelds the set does look a bit of a joke and must have been very heavy to carry around but, at the time, it was a radio telephone you could take with you into the field and actually use.

And Finally

In the next chapter I’ll continue the theme with several more of the Pye range that were available to amateurs back in the day, including some very cute handheld sets that still look good and stylish today. Cheerio.

Thanks

All history, development and facts are taken from, and with permission of, the Pye History Trusts super website:

www.pyemuseum.org

This article was featured in the October 2018 issue of Practical Wireless