Hi Kevin. Hope all is OK I saw on your web-site that you also had a category for the ARC-102 (Collins 618T). Feel free to use the following information. Especially the schematic diagrams are of interest. These were scanned by me from the overhaul manual, the file does not exist anywhere else on the internet. Feel free to either copy the files to your own site or create a link to my own URLs, as long as you mention the source: Loek d'Hont AC5XP If you have a fast link, try this for all docs in one zip file (14 MB) I'm currently restoring an ARC-102 installation but lack the time right now to complete it. If that changes I will also email you some pictures. I already have all the components. It now is just a matter of cleaning and refinishing it all, and building it on a larger rack
Collins 618T-3(x) File description:
This is the full schematic diagram package for the Collins avionics HF SSB radio 618T-(x). The military designation for this radio is AN/ARC-102 (for 618T-3) and AN/ARC-94 (for the 618T-1). This transceiver is a real Collins classic. I have had it in my collection for over 30 years. It is a 400 watt PEP SSB radio supporting USB, LSB, AM and FSK. Frequency coverage is 2 MHz to 29.999 MHz in 1 kHz steps. It uses two ceramic 4CX250 tubes in the final. All RF stages (both TX and RX) are done with tubes, the IF, AF and synthesizer stages are done with early transistors, so it is a hybrid. The DC-DC converter for the tube section supply voltage also is transistorized.
The quality of the transmitted SSB from this radio is phenomenal. The receiver also is incredibly good. One of the best radio designs ever done by Collins. The design stems from the sixties and was in production till early 80s. Numerous units were sold to both military and commercial customers, because of its phenomenal reliability. The radio also was used in land-mobile applications (as the military MRC-95 and MRC-108 in the US, and WS-C15 in the UK). It even has been used in maritime applications as a high-seas HF-SSB transceiver.
This PDF was scanned by me, from the original Collins 618T overhaul manual . It also contains a very rare interconnect diagram that was given to me by a Collins technician more than 30 years ago. These diagrams are not available anywhere else on the internet. The Collins 618T is an absolute classic. It takes some work to get all the sub-components together, but it is worth it. The best HF transceiver I have ever owned, and ever will own.
When you want to re-distribute this PDF file feel free to do so but please do so with source recognition: Loek d'Hont, AC5XP
Loek d'Hont AC5XP