Note
QST, Jun 1960, p. 107.
QST, Sep 1960, p. 113.
QST, Oct 1960, p. 107. (inside photo)
CQ, Nov 1960, p. 37 (inside photo)
QST, Jun 1966, p. 119.
CQ, Nov 1966, p. 14.
QST, Aug 1968, p. 5 (both 3341 and 3342).
Along with a new shape, the Communicator IV offered a higher power transmitter and a triple conversion receiver. It was introduced in 6 and 2 meter versions.
2 meters: model 3341.
6 meters: model 3342
220 MHz: model 3351 QST, Jan 1961, p. 123.
The word "Communicator" on the front panel may be in script form on early versions, and in block letters on later versions. Early and later versions also have different meter styles.
All three version were designed to work with Gonset's model 3357 VFO, usually referred to as the "Communicator VFO."
The #3409 civil defense kit (QST, May 1966, p. 119.) can be added to convert the Communicator IV for civil defense applications.
The #3362 civil air patrol kit (QST, May 1966, p. 119.) can be added to convert the Communicator IV for CAP applications.
It packs a separate transmitter, receiver, and a universal AC/DC power supply into a single small cabinet, eliminating the need for external cables, relays, or extra gadgets. Features an illuminated slide-rule dial driven by a dual-ratio planetary drive knob. It also includes an illuminated built-in meter that reads either RF output (for antenna loading) or "S" units. It features a front-panel spotting switch to display the transmit frequency on the receiver dial/meter. Six crystal sockets are located on the rear for frequency selection.
Power & Modulation: The transmitter runs 20 watts of input power. It uses a high-level speech clipping system providing 10 watts of audio modulation (instead of standard screen modulation), which results in a peak power of 80 watts.
RF Circuitry: The RF stage utilizes three 12BY7 tubes functioning as a crystal oscillator-tripler (supporting 6, 8, or 24 MHz VFO/crystals), tripling to 72 MHz, and doubling to 144 MHz. A 6360 dual triode final amplifier runs "straight through" for high efficiency.
Tuning: Coils are factory-peaked so that there is sufficient drive across the entire band without panel tuning, requiring the operator to only adjust the final tuning and loading controls when changing frequencies.
The receiver is a triple-conversion superheterodyne design, giving it excellent selectivity and freedom from image responses.
– Sensitivity Better than 1.0 microvolt (for a 10 dB S+N/N ratio) and a noise figure of 3 to 5 dB.
– Frequency coverage: 143.7 MHz to 148.3 MHz, covering CAP and MARS frequencies.
– Selectivity: The factory bandpass is set to 6 dB at 10.3 kHz, 20 dB at 15.5 kHz, and 60 dB at 47 kHz to meet civil defense (OCDM) requirements. However, users facing heavy interference can sharpen the selectivity curve down to 8.5 kHz by clipping three internal coupling capacitors.
Features: Includes an automatic noise limiter (switched via the front panel) and a squelch control (ranging from 0.1 to 50 microvolts) that allows for silent band scanning until a station pops in.
The audio system is the only section shared between the transmitter and receiver. It uses the pentode section of a 7059 tube as a speech amplifier/first audio amplifier, and a pair of 6BQ5 tubes in push-pull (Class AB1) acting as the receiver audio and transmitter modulator.
Features a push-to-talk ceramic microphone (designed for close-talking to minimize background noise) that triggers an internal relay to handle all transmit/receive switching.
A universal, built-in supply that handles either 117V AC or 12.6V DC. Switching is automatic depending on which power cord is plugged in. It uses four 1N1763 silicon diodes in a bridge circuit alongside two 2N1554 transistors for the DC source.
Tube Lineup (17 total)
(2) 6ER5 RF Amplifier and First Mixer
6J6 Crystal Controlled First Overtone Oscillator / Amplifier
6C4 Tunable Second Oscillator
(2) 6AV6 Second Mixer / Detector / Delayed AVC / First Audio Amplifier
6BE6 Third Mixer / Oscillator
(2) 6BA6 First and Second 455 Kc .IF Amplifiers
6AL5 ANL and Squelch
0B2 Voltage Regulator
(2) 12BY7 / 12BY7A Crystal Oscillator / Tripler and Doubler
6360 Final RF Power Amplifier
7059 Speech Amplifier and Phase Inverter
(2) 6BQ5Push-Pull Modulators / Receiver Audio Output
Power Requirements:
117V AC: 87.5 watts (Receive) / 110 watts (Transmit)
12.6V DC: 7.2 amps (Receive) / 10.3 amps (Transmit)
Available Accessories: Model 3365 Universal Mounting Kit, Model 3152 Telescoping Antenna, and Model 3363 Blue Carrying Bag ($12.00).
References
Brief description. Electronics World, Nov 1960, p. 136.
Review. 73, Nov 1961, p. 50.
