Valve Circuits Menu

Site Link	Description
Valve Circuits 1	Two amplifiers, five oscillators and one mixer
Valve Circuits 2	Beam deflection balanced modulator and one AF amplifier
Valve Circuits 3	Full break-in techniques including grid block keying, receiver mute and a valve T/R switch
Valve Circuits 4	Grid block keyed VFO, buffer/multiplier stages and a keyed HF PA
Valve Circuits 5	Stabilised valve power supply.
Valve Circuits 6	Beam deflection mixer and band pass filter

This page links to the various valve circuits pages which will be extended as time and inspiration permit.

(N) = New, (U) = Updated, blank = no recent change

1. Indirectly Heated Valves

2. 1.4v Filament Battery Valves

Link	Description
Valve Circuits B1	AF amplifier
Valve Circuits B2	RF amplifier
Valve Circuits B3	Mixers
Valve Circuits B4	Oscillators
Valve Circuits B5	Active detectors
Scope Probes	Some issues with conventional scope probes and suggested solutions when used with very high impedance tuned amplifiers and oscillators

Constructors and designers should be aware of important differences between low power battery operated directly heated valves and conventional indirectly heated valves:

1. The directly heated filaments are very fragile and completely intolerant of excessive voltages so over-voltage protection is required.

2. The average slope (gm) is lower so expect lower gain compared to indirectly heated valves.

3. The typical anode currents are much lower so much higher anode load impedances are required to obtain adequate gain. This means higher resistor value anode loads in AF amplifiers and higher L/C ratio tuned circuits in RF applications.