| Abbreviations used in valve tables |
a.c. | Filament normally run from an AC supply |
AF | Audio Frequency |
bt | Beam tetrode |
B | Bright emitter |
CD | Critical distance (tetrode) |
D | Dull emitter |
d.c. | For DC mains operation with series connection |
DC | Direct coupled (amplifier) |
deg | Degrees of shadow angle |
DH | Directly heated cathode |
det | Detector |
FC | Frequency changer |
fmax | Maximum frequency |
FW | Full-wave (rectifier) |
gc | Conversion conductance of frequency changers (See also the symbol used to indicate this.) |
gm | Mutual conductance (slope) |
GP | General-purpose (valve) |
h | Hexode or heptode section of frequency changer used as a mixer |
HW | Half-wave (rectifier) |
IH | Indirectly heated cathode |
IO | Rectified output current |
mix | Mixer section of frequency changer |
mu, μ | Amplification factor |
MV | Mercury-vapour rectifier |
O | Oxide coated cathode |
osc | Oscillator section of frequency changer |
ot | Output triode |
p | Pentode |
PIV | Peak Inverse Voltage |
PO | Power output |
PW | Post War |
r | Rectifier |
ra | Anode dynamic resistance |
RC(C) | Resistance-capacitance coupled |
RF | Radio Frequency |
RK | Cathode resistor for auto bias |
RL | Optimum load resistance for specified output power |
r.m.s. | Root mean square |
st | Side terminal on valve base |
t | triode |
t/b | Timebase |
tet | Tetrode |
tc, tp | Top cap/Top pin |
tt | Top terminal (i.e. screw terminal) |
VHF | Very high frequency |
VD | Voltage doubler rectifier |
VM | Variable-mu |
UHF | Ultra high frequency |
| Symbols used in valve tables |
* | Appended to filament voltage, indicates directly heated |
* | Appended to filament current, indicates centre-tapped filament |
| enabling it be operated at twice the voltage and half the current |
_ | Underline in RL column is the anode-to-anode resistance, in Va |
| column is total anode current and in RK column is common |
| resistance feeding both valves |
⅄ | Indicates conversion conductance |
