Pye PMR Sets
Bernard Nock G4BXD continues his overview of those Pye PMR sets that were once so popular with radio amateurs
Bernard Nock G4BXD continues his overview of those Pye PMR sets that were once so popular with radio amateurs as a way of getting going on the VHF bands.
Continuing one from my last chapter (two months ago) where I covered the Pye-made PMR (Private Mobile Radio) sets Ranger, Cambridge and Vanguard, I would like to continue with a further selection of these popular radios available to the radio amateur during the 1960s to 80s. These PMR radios were abundant at rallies and the like and were at least a great source of parts if you did not want to actually re-align them onto an amateur band.
Many radio amateurs in the 1960s, 70s and 80s, myself included, used nearly all of these types at one time or another, some on the 2m band, some on 70cm and even on 4m. We did not have the 6m band at that time so that band was not catered for in published modifications and the like.
The Pye Westminster was the fifth-generation mobile technology platform since 1947 and a major family of all-transistor PMR mobiles (except the PA valve of the W30). First introduced in 1967, the Westminster, Fig. 1, was claimed to be the world’s first all-semiconductor PMR mobile, and more than 120,000 were produced.
The standard range covered AM and FM VHF models in front mount, remote mount, transportable, marine, motorcycle and universal mounting versions, plus various ancillaries such as battery chargers, power supplies, carrying cases, etc. The equipment construction although hard-wired, was essentially modular, Fig. 2, using small PCBs for each of the main circuit functions mounted on a double-sided aluminium platform chassis.
Many common PCB and circuits were shared with the fixed stations of the time. The product also marked the change in product colour scheme from Dimenso blue hammer finish paint to a blue/grey textured acrylic.
In addition to the range of standard VHF 6-15W front and remote mounting equipments mentioned above, other higher power or specialist versions also evolved, including the W25FM, W30AM, LW15FM radiophone, W15U and W20U UHF. These models all utilised a longer chassis and mounting cradle than the standard short VHF models. The product was replaced by the M200 Olympic series of AM and FM front and remote mounts, which overlapped in production dates.
Facts; 1967 to 1978. 25 to 174MHz, (Pye A, B, C, P, E, G, H bands), 402 to 435MHz (T3), 450 to 470MHz (U) A, B. W15FM 15Wa.
The Westminster was a really modern design with sleek clean lines and found favour in many a shack and mobile setup. It was easy to tune up on the amateur bands and with either a six or ten (or maybe 12, I forget) channel oscillator board fitted, the local repeaters and several simplex frequencies were easily catered for although, of course, each channel required the purchase of two crystals. These were the days long before synthesised sets and DDS VFO boards.
As mentioned, there was a ‘high’ power version of the Westminster, Fig. 3, which had an extra-long case that housed the valve PA stage and inverter power supply. The output valve, Fig. 4, was a quick-heat type. In other words, when the PTT was pressed, the heaters of the valve, 2.1V at 4.5A, were connected and full output was achieved in about half a second. This meant that the set was only pulling minimal current during the receive periods, a bonus in the cold days of winter and poor batteries.
A special version of a boot-mounted Westminster, Fig. 5, saw service in the Police and such for use on motorbikes. Special in so much as it sported a nice shiny white paint scheme and the connectors where changed to large screw-on types making them more robust and vibration-proof for bike use.
The set was usually mounted behind the rider above the rear wheel with the control box sitting on top of the set, as in the picture, or sometimes on top of the fuel tank and an extension PA-type speaker mounted in front of the rider either atop the handlebars or behind the leg fairing, depending on the bike. A ‘green’ version, Fig. 6, was made for a similar role in the military.
Looking very much like a boot-mount Westminster, the Whitehall was a fascinating set and had an interesting history. The W20AM/FM Whitehall was an AM/FM remote-mount mobile initially created for the British Home Office at a time when some British County Police Forces used AM transmission and others used FM transmission.
The Whitehall allowed UK police vehicles to communicate with the local network infrastructure in any county when operating away from their home area. The W20 equipment was subsequently purchased by the Ministry of Defence for use by the RAF and for various other projects such as nuclear weapons convoys, etc.
The equipment was based on the Westminster design printed circuit boards but used a different and larger chassis, lids and mounting cradle and generated slightly higher transmit power. The control box was also a dedicated design.
One interesting combination was designed to meet a UK Home Office requirement for Police communications and comprised two sets, a simplex VHF set and a duplex UHF set, a common control box and handset. With this system, four operating modes were available:
1: Automatic two-way talk-through between VHF and UHF.
2: Manually controlled UHF duplex.
3: Normal simplex on the VHF set, and
4: On-site automatic talk through using the duplex UHF set.
The first setup apparently used the W20AM/FM Whitehalls as the VHF link and a duplex W15U UHF set. Later systems used the W25DM on the VHF side.
The MF5AM Motafone, Fig. 7, was a single product, lightweight, low cost, all-transistor AM mobile, designed primarily for the UK market, and was the forerunner to the FM Europa series. This sixth-generation technology mobile product introduced the use of integrated circuits and reduced the component count compared to the Westminster.
It was designed to be a limited feature front-mount-only product, positioned below the AM Westminster, at a time when cheaper competing products were taking market share from Pye Telecom. The construction used an aluminium chassis with a separate vinyl-clad sleeve wrapper and front panel. An internal loudspeaker was fitted and the audio output power was limited. The product was replaced by the MF6AM AM dash mount set.
Facts: 1972. 68 to 88MHz (E band), 118 to 136MHz (C band), 138 to 141/105 to 108MHz (Mid band), 148 to 174MHz (A band). 2.5W.
The AM Motaphone found favour with many amateurs when it came out of service for use on the 4m band. 70.26MHz was the calling, and working in most cases, frequency in those days, albeit AM in the main although with some FM as well later on. Being lightweight, small and compact, the set did not take up that much room in the shack or under the car dashboard for that matter.
The Motophone was also supplied in Airband frequency coverage and branded as the Pye Pilot, primarily for use in gliders, I believe. The Motaphones could also be supplied in a portable housings, with built-in battery and mounted whip antenna and in this guise were called the Pye Portaphones.
All of the sets mounted in the boots of vehicles needed a small control box, a box with switches and potentiometers, Fig. 8, for On/Off, Channel change, Volume and Squelch at least. Other boxes allowed two radios to be connected so as to act as a repeater, receiving on VHF and retransmitting on UHF, for example, as mentioned.
The early boxes for Vanguard and Cambridge were rectangular in shape while the later Westminster boxes, Fig. 9, were a little more stylish. The bigger units pictured were originally used with the Westminster family and were apparently first designed for use in Canada in the late 1960s early 1970s. There were several versions and some did not have the channel control because some were add-on units connected via the Canon ‘D’ facility socket on the back of the later dash-mount Westminsters. Some included selective calling as well as a search-and-lock feature. There were even control boxes disguised as standard car radios, presumable for undercover police cars, Bodie and Doyle’s CI5 (how many remember The Professionals? Still being shown on some TV channels! – ed.) and the like.
Over the years ex PMR equipment has furnished the hobby with tremendous amounts of equipment and provided a great technical and cheap training base for builders and operators alike. The lack of such equipment today does mean that few amateurs have the opportunity to easily build or adapt anything, which is a great loss to the hobby I feel. Speaking for myself, I feel I learnt a lot while playing with this type of equipment. I gained a good technical knowledge and experience of RF techniques in particular, which otherwise I wouldn’t have had. In Part 3 I’ll bring you some cute little baby handheld sets of the period. Cheerio.
(As in the previous instalment, all history, development information and facts in italics are taken from, and with the permission of, the Pye History Trust’s super website):
This article was featured in the December 2018 issue of Practical Wireless