Ferranti BT1037 transistor table radio

[dazzlevision]

I’ve been thinning out my collection of radios of late (I can’t move for them!) and decided to dismantle this one, as technically, its performance on VHF/FM would be inferior, due to the lack of a tuned RF amplifier stage prior to the self-oscillating mixer. The cabinet is also rather scruffy. In addition, it uses the “tin whisker prone” OC170 and OC171 Germanium transistors in the VHF RF unit, the AM mixer/oscillator and IF amplifier stages.
I’ve not found any threads on this design, so I thought I’d post a few photos here, together with a brief description, as it is rather unusual.

The Ferranti BT1037 (same chassis also fitted in the Ekco BT359) is a battery powered table radio, made in 1960. The Ekco designers decided to mount three OC170 transistors on a slider switch (more at home in a 405-625 dual standard TV), which was soldered to two printed circuit boards, mounted at right angles to each other. One board houses the AM mix/osc, IF amp and AM detector circuitry. The other houses the VHF IF amplifier and FM detector. At the rear of the chassis, is a “swing down” AF amplifier board. The VHF RF unit is variable inductance tuned, with the circuitry contained on a small PCB.

Upon powering up, there was no output on AM or FM, but a slight hiss from the AF stages. Touching the volume control’s slider connection produced the usual buzz. Measuring voltages on the three OC170 transistors mounted on the AM/FM slider switch, it was obvious that they all had issues. Accessing the OC171 in the VHF unit looked to involve a considerable amount of dismantling, including drive cords, so this sealed the radio’s fate (together with the large number of Hunts "Moldseal" and "DCC" - Dubilier Condenser Company paper dielectric capacitors).

Not many transistor table radios were made by UK manufacturers, probably due to the concurrent arrival of the portable transistor radio. The other example I have is a AM/FM Ferguson 626BT, which is of conventional hand wired chassis construction and performs rather well (after restoration).

[dazzlevision]

A few more photos....

[AlanC]

I've not seen the circuit but it looks almost like the 'system switch' quite literally switches the transistors either into the FM IF strip or the AM mixer/osc and IF... Very unusual!

[Nuvistor]

That’s correct, Snippets from the R&TV info available from the Service Data.

[dazzlevision]

Originally Posted by AlanC

I've not seen the circuit but it looks almost like the 'system switch' quite literally switches the transistors either into the FM IF strip or the AM mixer/osc and IF... Very unusual!

That’s exactly what it does!