Radio Unit BT1

Radio Unit, BT1

Ideal for tuning into “local” or more powerful stations, being a straightforward HF circuit.

The aerial input is taken via a tapped aerial coil to the grid of the HF valve, an HF Pentode.
This is followed by a tuned HF transformer feeding both diodes of a double diode triode valve. Both tuning coils are of the air-cored low loss type tuned by a two-ganged condenser.

The diode detector circuit is conventional, using a low value of diode load to prevent distortion on deeply modulated passages.

Residual HF is prevented from reaching the grid of the first low-frequency valve by a HF choke and bypass condenser.

The rectified speech currents are taken to the Radiogram switch which is combined with the wave change switch and coupling is made to the grid of the triode portion of the valve via a 0.5 µF condenser, which in conjunction with the value of leak used maintains the efficiency of the response at very low frequencies.

The coupling resistance in the anode circuit and the associated condenser are calculated to give freedom from amplitude and harmonic distortion rather than a high gain for the stage. The condenser feeds the volume control which acts as the leak of the following valve.

This position for the control is chosen to prevent attenuation of high frequencies when using a pick-up of the crystal type at low volume and resistance is shunted across the pick-up sockets to level the peak in the bass which otherwise appears with this type of pick-up.

Controls: Tuning: volume: combined wave change and Radiogram switch.

Current Consumption: 20 mA at 250 volts and 2.6 amp at 4 volts including dial lights.

Connections: Two pin sockets for aerial and earth and a five-pin socket and plug for heaters earth between chassis

Hier finden Sie 56 Modelle, davon 51 mit Bildern und 2 mit Schaltbildern.
Alle gelisteten Radios usw. von Lowther Manufacturing Co; Kent