The RD-75 radar trailer was added to the S-75 system to improve performance in jamming environments. It was slaved in azimuth and elevation to the boresight of the SNR-75M3 Fan Song (available as a separate model) and was employed to perform precision range finding when the range finding channel in the Fan Song was degraded or compromised by jamming. This was the situation later in the Vietnam war. Further information can be found at https://www.ausairpower.net/APA-SNR-75-Fan-Song.html (second section) and at https://infowsparcie.net/wria/o_autorze/rd_75_amazonka.html (requires translation). The trailer was towed by a suitable truck, such as the ZIL-157 (model also available).
The RD-75 was based on the MAZ-5206 trailer, and this is provided as the foundation for this model. the main trailer frame is the core part, and a separate dolly provided to permit the towing bar assembly to rotate to suit parked or towed positions. Two versions of the trailer are provided, one with the supporting legs up, and one down. The double wheels are provided as a single item; four will need to be printed. A single spare wheel design is provided to fit under the trailer frame. The radar assembly is in two parts, with the radar reflector and feed horn as a single part that should be printed with minimal or no supports. For increased fidelity, the front of the reflector can be covered in a fine foil or nylon mesh. The radar support can be left free to rotate in the hole in the roof of the main cabin, that can be glued directly to the trailer frame.
Further elements of the S-75 system are planned, including the electronics cabins, generator trailers and additional radars. The missile guidance radar SNR-75 is already available on this site, with the base missile, launcher and transporter.
The product is offered for personal, non-commercial use under the Attribution-NonCommercial 4.0 International (CC BY-NC 4.0).