Below: RT-698/ARC-102 transceiver unit. It is the primary component of the 618T-3
Below: 678P-1 test harness.
Below: 678Z-1 Test Set
Below: 678Y-1 extension module kit.
618T-3
Built by Collins, the 618T-3 is an airborne fully synthesised HF transceiver. It covers 2-30 Mhz on USB, LSB, AM and CW.
Below: RT-698/ARC-102 transceiver unit. It is the primary component of the 618T-3 Below: 678P-1 test harness. Below: 678Z-1 Test Set Below: 678Y-1 extension module kit.
COMMENTARY
The 618T-3 is part of the 618T series of transceivers. The 618T-3 is the 28 Volt version. The 618T-2 is the 115VAC 400Hz version. The 618T was designed as an airborne HF transceiver and saw extensive use in the Air Force
and also on commercial aircraft. It was also used by the Army and Navy. The system is built to the standard one would expect from Collins. The transceiver unit is of
lightweight modular construction, and mounts in a rack into which the control connector mates. The basic system consists of the 618T transceiver unit, a control head and antenna tuning unit.
Racks and cable assemblies are generally not available, as that is a part of the aircraft wiring harness. The set is capable of 100Watts RF output, AM, CW, USB or LSB. Power requirements are 28V DC 40A, and 115VAC 400Hz 100W.
The actual transceiver unit has a meter and meter switch for monitoring critical voltages. There are 1/4 inch jacks for headphones and a microphone. There is a blower mounted in the front of
the unit for cooling. The control head is used by the operator to control the radio. Rotary switches are used to select the frequency in 1 KHz steps. There is also a mode switch and a squelch control.
The 678P-1 test harness can be used to interface a transceiver unit to a control head. It also doubles as a dummy load and directional wattmeter. The unit has jacks for all necessary audio
signals. For ham use the 678P-1 makes a good base for a control station for the set. The 678Z-1 is a test set for troubleshooting the system, and the 678Y-1 is a module extension kit to allow access to modules whilst plugged in.
The 618T is good for ham use, once you've got it working. Harnesses are generally not available, and suitable connectors are difficult to find. Its big advantage is that it supports both
USB and LSB, which is quite unusual for military radios. I am yet to get mine working because of the difficulty of getting a harness.
TECHNICAL SPECIFICATIONS
Frequency Range: 2-29.999MHz in 1KHz steps
Modes: AM, CW, USB, LSB, Data.
Voltage Requirements: 28VDC 40A and 115VAC 400Hz 100W
Power Output AM/CW: 125W RMS
SSB: 400W PEP
Sensitivity: SSB 1uV, AM 3uV.
CONSTRUCTION
The construction of the 618T is a high quality and compact design. Its modular design minimizes space. Tuning is completely automatic, being performed by a servo motor and a massive gear-train typical of Collins which interconnects the modules.
Below: 618T transceiver unit. The modular construction is apparent.
OVERALL RATINGS
Engineering rating (taking into time of design).
Nicely constructed. Easily a 9/10
Fitness for purpose rating
Has been extremely popular for many decades. 10/10.
Usefulness as ham equipment rating
Difficult to make operational. 8/10