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@ 1ef695e1:15351d5f
2024-11-29 06:13:46My Vietnam era Collins 637M-1 HF field antenna erected and tested. I could not find any information about the antenna on the internet, but I had feedback from hams on some of the Collins groups. The guy ropes were no longer to spec, so I replaced them with UV resistant polyester rope.
The transceivers normally used in conjuction with the antenna are the Collins AN/TRC-75, AN/TSC-15 and TRC-146.
A frequency range from 2 to 30MHz that operates as either a fan dipole with horizontal polarization or a top hat vertical monopole. The sectional vertical is a 50ohm feedline when used as dipole and the same vertical becomes a radiating element when coupled to the alternative feedpoint on the baseplate6.
The balun is a wire that is attached to the one side of the longer dipole and runs down the vertical through offsets to where it either connects to a lower section of the vertical or is disconnected and open.
The antenna comes in an aluminum trunk with carry handles and erection is a two man task. The antenna is 12 meters high and can be rotated through 90 degrees by hand with a latch on the baseplate to give directional coverage.
The antenna can handle strong winds with four upper guys and four lower guys.I found that the antenna tunes up easily for both horizontal and vertical use and test contacts were made on the 40 and 20m bands horizontal locally and on the 10m band DX to Europe vertical with readabilty and strength as expected from a widebanded military antenna.
The original connectors (as seen in the manual photo) being impractical, were changed.
Balun Switchham