Receiver-Transmitter RT-68/GRC and Power Supply PP-112/GR

1950's military low-band VHF radio equipment.

RT-68 Summary:
38-54.9 MHz FM continuously tunable or 100 KHz-step channels. Receives and transmits both voice and 1600 Hz ringing tone using wideband FM (+/-30KHz deviation); range 10-15 miles. Receiver circuit has variable 1st IF 4.45-5.45 MHz and fixed 1.4 MHz 2nd IF; also squelch and 600 ohm audio output. Transmitter uses crystal-controlled oscillator and oscillator power amp; power output 2 watts (LO) or 15 W (HI). Also meter to monitor xmiter filaments and 90 V input. Requires PP-109 or -112 power supply. Tubes 4/1U4, 2E24, 2/1A3, 2/1L4, 4/1R5, 2/1AE4, 1S5, 4/3Q4, 3A4, 3/3A5, 2/3B4, 6AK5. 9x13x11.3, 42 lbs.

PP-112 Summary:
24 VDC operated power supply for RT-66-67-68 transceivers; provides all voltages from 24 VDC 6.5 amp input. 7.3x9x13, 39 lbs sh.

Related equipment installable on the mount shown:
PP-109/GRC SUPPLY, as PP-112 but 12 VDC 12 amp input.

Important related items:
CX-1211 interconnect cable RT: PP Units
MANUAL for AN/VRC-8-9-10
Manual TM 11-611
C-434 LOCAL CONTROL p/o GRA-6 (allows remote control of radio by field phone and wire)
C-435 CONTROL for duplex GRC-3--8 (used with above; at the other end.)

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RT-68 [large image]
PP-112 [large image]


Receiver-Transmitter, RT-68/GRC
JAN Type: RT-68/GRC
Nomenclature: Receiver-Transmitter
Reference: TM 11-611
NSN: 5820-00-503-1505
Weight: 35 Lbs
Size: 9 x 13 x 11-1/4
Mode: 30F3
Frequency Range: 38-54.9 MHz
Power Input: 12 or 24 VDC from PP-109 or PP-112
Power Output: Low: 2, High: 16 W
Number of Channels: Continuous Tuning or Detent 170
Channel Spacing: 100 kHz
Part of: GRC-7, GRC-7X, GRC-8, GRC-8X, VRC-18
Description: Receiver-Transmitter RT-68/GRC is the receiver-transmitter of Radio Set GRC-7, GRC-7X, GRC-8, GRC-8X or VRC-18. It provides continuous tunning or detent tuning with 120 100 kHz channels. This radio set covers the infantry frequency range.

Power Supply, PP-112/GR
JAN Type: PP-112/GR
Nomenclature: Power Supply
Reference: TM 11-611
NSN: 6130-00-284-0230
Weight: 33 Lbs
Size: 8 x 13 x 9
Power Input: 24 VDC
Part of: GRC-3, GRC-4, GRC-5, GRC-6, GRC-7, GRC-8, VRC-16, VRC-17, VRC-18
Description: Power Supply PP-112/GR is a vibrator power supply providing the power from 24 VDC vehicle battery for Radio Sets GRC-3 to -8 and VRC-16 to -18.

More information including a schematic may be found at