TIME DELAY CIRCUIT P/O MODULE A2100.

TM 11-5820-670-30

1-18. CRS HUNT DISCRIMINATOR A3600, CRS PHASE DISCRIMINATOR A3700, AND REFERENCE

OSCILLATOR A2000. (CONT)

The two signals entering the phase discriminator are 5.65 MHz from the reference oscillator and 5.70

MHz from limiter A3500. Because of the difference in frequencies, the phase discriminator outputs a

dc voltage. This positive dc voltage is measurable at TP3001.

1-19. TIME DELAY CIRCUIT P/O MODULE A2100.

EL1AT124

Voltage regulator assembly A2100 contains the time delay circuit which operates relay K3001 in the crs

when the 16 vdc supply is turned on. As power is applied, current flows through Q2103 and the coil of

relay K3001. Relay K3001 energizes, sending the error signal from the crs phase discriminator to

ground, while Q2103 charges the charging network. When the charging network is fully charged,

Q2103 is biased off, deenergizing K3001, which then allows the error signal from the phase discrimi-

nator to correct the frequency of the local oscillator.

When the radio set is tuning, by rotating the tuning dials, gearbox assembly A9700 supplies a ground

signal to the charging network. The ground signal discharges the network and causes relay K3001 to

energize. When K3001 is energized, the error signal from the phase discriminator flows to ground,

allowing the local oscillator to change frequency.

If power is removed momentarily and then reapplied, components in the charging network will allow

the time delay circuit to operate.

1-19