Korean War MARS Operations
Back when I was only a teenager, in the 1950’s, My brother-in-Law was a Marine flying choppers in Korea. I wanted to help out so I joined the 6Th Army MARS group and one of the opportunities I had to help was to run phone patches (Called ZAF’s) for the troops.
My station was a Heathkit DX-100, 100 watts, to a 3 element beam. Propagation was pretty good back then and I was able to make a lot of patches from GI’s back to their families. I had to call them Collect, (that is where the receiving party had to pay for the call charge to my house).
We used MARS frequencies (27,994 kHz), My main contact was AD4BE (Jack, W1YYD). He was running a BC-610 into a Sterba Curtain. He was in Wonju, in the KMAG, Military Advisors Group. 8202 Army Unit, KMAG, APO 102, S.F.C. http://www.koreanwar2.org/kwp2/cmh/military_advisors_in_korea_kmag.pdf
(The AD4 call was an Army MARS call, that was many years before the FCC started to use those 2x2 call for regular amateurs). He made me a QSL card on old mimeograph machine.

There were Marines in Yokosuka (KA2AD/KA2NY) and some in Okinawa. A USAF MARS station, (ZLK) from New Zealand was also active.
My phone patch was a MacGyver type, using an old power transformer. The 110VAC winding went to the telephone line, The 6 VAC winding went to the speaker, and the HV winding went to the microphone input.
The XYL’s in the USA really appreciated the patches to Korea.
Many other MARS stations in the USA made phone patches for the troops during that time.
Paul w0rw