Apparently a lot of people have been looking for this gem of an eBook and the associated images that were lost in the move to WordPress. The content has now been imported and a new gallery created so this excellent work lives on.
Racal RA117 + RA218 ISB adaptor, fitted with spurious front panel labels. Complete and fully functional. More complex but cleverer than the RA17L, and capable of operating with an early synthesizer called a “Racalator”.
Racal RA17L underside view, showing cast compartments. Critical filters live under the L-shaped covers left in position here. The box at the bottom right contains the antenna attenuator switch.
Two S130Ps: LHS is a balloon-top Cossor, RHS is a GEC in shouldered glass. They have very different regulation behaviours. Not all GEC S130Ps glow orange. Notice the wire mesh priming electrode inside the LHS valve.
Racal RA17 original prototype. The left and right are NOT two separate castings. Difficult problems of spurii led to the original single casting being bandsawed into two completely separate halves. Look carefully and you will see the sawcut! This broke the path of the earth current, enabling correct performance to be achieved.
Racal RA17 prototype, all pretty much as would be expected apart from the 5Z4G rectifier, which must have worked too hard in this application! The famous sawcut is in evidence from left to right of the chassis, just below halfway down.
Racal RA17 prototype underside, showing a single screening plate with the large retrospective bandsawed cut-out to achieve correct grounding and proper routing of earth currents. Production RA17s had a more complicated screening arrangement.
AWA CR-6A and CR-6B radios, one with the correct table cabinet and the other with the optional multi-channel unit. Somewhat smaller and lighter then the norm, these are among the writer’s favourite radios.
AWA CR-6B chassis topside, all very open and straightforward. This radio has the optional multi-channel unit fitted. The Cadmium plating is in good condition and the chassis looks much as it would have done when new
AWA CR-6B RF unit showing the demountable construction and the use of topclass Philips beehive trimmers having proper leadscrew adjusters. Why did not more manufacturers use these components? The variable capacitor shows its ceramic shaft in this photo.
AWA CR-6B pre-adjusted demountable IF block filter, also showing the optional six position multi-channel module. This perfectly sound idea was next seen years later in the Pye Cambridge mobile radiotelephone.
AWA CR-6B chassis underside showing the proper fitted cover beneath the RF unit to stop draughts and promote frequency stability. The mighty bandchange roller chain is rather as seen in the RCA AR-8516L - but the AWA implementation works better. The selectivity wafer switch at the top of this photo forms part of the IF block filter module. Notice how easy this set is to work on - very intelligent design.
AWA CR-6B close-up of the selectivity switch, carried on a metal bracket which also accommodates the five 100kHz IF coils. No nasty micas to drift away from the correct values! Notice how the main radio chassis is fitted with Mullard tubular polyester capacitors. These are about the only type still considered reliable some fifty years after they were made.
KW2000E is a very handsome transceiver. This is the final model, which tunes in 500kHz segments. It has RIT, TIT etc and good VOX facilities. It came to be known as the “E for Expensive” variant!
KW2000E interior, showing conventional chassis construction and at lower right, the dropper for the 150V zener HT regulator. An 0A2 neon had been fitted to earlier models. The large cylindrical can is the Kokusai mechanical filter.
KW2000E vertical FR4 PCB was termed the “KW Vox Box”. It may perhaps have been standard fit instead of an option as on earlier models. The oversize washer on the PCB corner was fitted by the writer to protect transformer IFT5 when the chassis is being handled on the bench. The large B9A valve fitted with the spring retainer is the ECL82 for audio output.
KW2000E rear panel, showing the small Painton multi-way connector which carries raw mains, +1000V HT off load, and transistor supply voltages from the external PSU box. The metal shell of the mating connector is not even grounded. This is extremely dangerous equipment design. Notice the absence of a “Danger High Voltage” warning label. There should certainly be one!
KW2000E showing plastic boxes added by the writer to improve frequency stability and reduce dust ingress. Notice the yellow Kapton tape covering a hole on the top of the VFO module. This aperture is directly below the finger-hole in the cabinet top cover. A delicate Philips beehive trimmer lies directly underneath. The tape stops debris falling into the VFO, and also captivates the bulb wiring.
GEC BRT400D showing the desirable fan modification. This model otherwise gets far too hot to be reliable. This version predates the BRT400K. Three B8G valves, an octal and three B7Gs are shown in this photo. The unusual B7G valvecans are original to this radio.
British Army R209 Mk2 power unit, showing the solid-state vibrator. It works very well, but forces the radio supply polarity to be negative earth. The original WICO mechanical vibrator made no internal connection to its can, so did not cause this problem.
RCA AR-88D chassis underside, showing excellent screening arrangements. All rotary switches have ceramic wafers like those shown here. The multisection smoothing block is being rebuilt using 3 pairs of 10µF/450V/105°C high reliability electrolytics in series, each capacitor strapped by a 220kΩ TR6 metal oxide voltage balancing resistor. This gives 5µF/900V/105°C per section instead of 4µF originally, with a total effective bleed resistance of 147kΩ.
I am trying to get access to a new band, for Australian Amateurs. Originally a UK band, much of Europe, plus parts of Africa and the Middle East now have it. It will allow experimentation, including with Trans-Equatorial Propagation, as well as being handy during emergencies.
