BUSH DAC 90A RESTORATION

One of my most recent restorations was the refurbishment of a British made Bush DAC 90A Medium/Long wave radio from the 1950's. The DAC 90A radio was introduced in 1950. This model superseded the DAC90 and uses smaller valves and a completely redesigned chassis. It is a five valve super-heterodyne receiver with a well laid out chassis housed in a beautiful Bakelite cabinet. It is an excellent candidate for restoration as it is well laid out and easy to get to all of the components. The restoration consisted of:

1. Replacement of the UL41 audio amplifier valve (V4) which was causing a loud distorted hum, a common fault
2. Replacement of the UF41 RF stage amplifier (V3) which had reduced output
3. Replace valve 3's faulty valve base which was making bad contact
4. Replaced the 460K resistor in the audio amplifier stage which had gone high resistance (600K+)
5. Removed components from pin 4 of V3
6. Replaced all wax coated paper capacitors with modern equivalents (re-capping).
7. Replaced power supply smoothing capacitors C20 and C21 with modern equivalents
8. New mains cable as the old one was broken and dangerous
9. Removed all dirt and grime from the radio chassis and speaker grill
10. Cleaned and polished the Bakelite case.

The MW and LW radio bands are rapidly being abandoned by more and more radio stations in favour of FM, DAB/2 or Internet transmission. Even FM is being abandoned in favour of DAB/2. This means that the choice of radio stations for listening on MW/LW is very limited. However the Raspberry Pi Internet Radio project shows how a Vintage Radio can be interfaced to Internet Radio streams allowing almost unlimited access to radio stations over the whole world or even playing music from a USB stick or network share. Below is a photo of a low powered (1 milli-watt) AM transmitter which can connect to any audio output to the transmitter with a standard jack plug. See the Internet Radio Vintage Supplement for further information