The R.I. Airflo 451 — often written “Airflow 451” — is a British valve radio made by Radio Instruments Ltd. of Croydon, Surrey, shortly after the Second World War. Contemporary catalogues list Radio Instruments’ proprietary radio names as Airflo and Aria.
Valve Lineup
- TH41 — mixer-oscillator
- VP41 — IF amplifier
- HL42DD — detector, AGC and first audio amplifier
- Pen45 — audio output pentode
- UU6 — full-wave mains rectifier
SERVICE MANUAL PREVIEW
The Trader service sheet for the R.I. Airflo models 451, 451A and 451B is available to members. Here's a taste of what's inside.
These pictures are faded on purpose, just for this preview. Members get the complete service sheet, unfaded, to view and download.
The service sheet includes:
- The full circuit diagram, with a diagram of the speaker plug
- Component values, with where to find each one on the chassis
- Valve analysis, with the voltages and currents
- Diagram of the waveband switches, with a table of switch positions
- How to dismantle the set
- Notes on the differences between the 451, 451A and 451B
- Step by step circuit alignment
- Photos of the top and underneath of the chassis
