Howdy,
Multichannel 2-ISB and 4-ISB HF systems were pretty common from the late 50s through the early 2000s. The Navy had numerous 4-ISB systems for multichannel data using TMC equipment, and AT&T and others had overseas telephone systems in use into the late 1990s using Harris RF-740M 4-ISB transmitters. With the proliferation of satcom, HF ISB systems are less common today, but you can still find 2-channel ISB systems carrying Link 11. In the Gemini and Apollo space programs, NASA used TMC 4-ISB TSTE-10K transmitters and DDR-506 receivers with 1200 baud modems for passing mission control data to and from the Range and Instrumentation Ships in the NASA Ground Network. These were in use from 1964 to 1980 when they were replaced with the Collins HF-80 system.
Originally, 4-ISB was accomplished with wideband ISB equipment having two 6 kc or 7.5 kc sidebands and used baseband multiplexers to provide 4 voice bandwidth channels within the two sidebands. By the mid 1960s, 4-ISB radios eliminated the need for the baseband multiplexers. Collins, Harris, TMC, RACAL, Sunair, and others made 4-ISB HF equipment. Around 2004, Sunair displayed a 4-ISB HF system at the Melbourne, FL hamfest. The Sunair guy told me they were used in long-distance telephone systems in South America.
73,
John K9WT
Have the documentation on the 851S-1 and from looking at that it appears a lot of the same cards are used in both. The 8054 receiver in the video only has a 100Hz step via the front panel but allows you to move in 10 Hz increments by remote control and they do have an option of 1 Hz on that family of products. Yes, for band cursing nothing beats a knob! Think that’s my biggest complaint about the Harris RF-350K family is it’s a real drag tuning around with them. Have the Harris R-2368 for RTTY but the companion exciter, the RF-1310 has to have frequency manually entered and that’s a real drag. Also the Harris Falcon stuff is far from soring when it comes to band cursing. Just goes to show the difference in mind sets between military and commercial think and Ham use.
Along those lines, the 8054 has four independent side band cards, upper, lower upper upper and lower lower. Use to seeing things like the General Dynamics R-1051 sets with independent USB/LSB and know of applications where two audio streams were carried at the same time but have to wonder if there were any four channel Collins links established? Maybe up north or something? I know it will cheese of all the Collins people out there but the entire HF-80 line always looked a bit like telephone carrier equipment to me.
Ray F/KA3EKH
From: W2HX <[email protected]>
Sent: Tuesday, February 3, 2026 2:42 PM
To: [email protected]; Ray Fantini
<[email protected]>; [email protected];
[email protected]
Subject: RE: HF-80 video
Very nice! I have that receiver along with a 1KW transmitter setup. My plan, however, is to replace the receiver with an 851S-1 I bought. That way you get the VFO. I like to have a VFO on my receivers (at least). Find a station and then punch that into the transmitter (if controlled separately).
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