Tektronix 067-0532-10 Calibration Fixture Manual page 52

General Radio Oscillator
Circuit Description
The oscillator uses the General Electric Type 2C43 metal-and-ceramic
planar, triode tube.. The tube is designed to operate with 6.3 V and
0.9 A on the heater and a maximum plate voltage of 500 V. The tube is
used in a Colpitts circuit (Figure 8-3) with the plate and grid connected
to the tuned circuit LC101. The cathode is grounded for rf. The feedback
is determined by the inter-electrode capacitance of the tube, and capacitance
associated with the tuning element structure.
wi
<>)
|
4 | ~ s
At high oscillator levels, the resistance in the grid-leak circuit
The 1363 VHF Oscillator uses a "contact-type" circuit, which combines
a variable air capacitor and a variable inductor in a single unit.
Inductance varies from 0.06 uwH at the low-frequency end to 0.01 uH at
the high-frequency end, and capacitance varies from 130 pF to 9 pF.
Rotor and stator plates are shaped so that frequency varies logarith-
mically with dial rotation. Special damping elements are used to over-
come undesired resonances in the inactive portion of the tank circuit
(C3, Cll, R2, R4, and RS.
Radio-frequency power is coupled from the oscillator tank circuit by
means of a loop located near the oscillator tube. The loop is
connected by means of a 93-0 coaxial cable.