M35 Commo Truck 23 June 2007

"Field Day" with the Irving Amateur Radio Club

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RT246 military radio covering 30 to 75 MHz FM. Works great on 6 Meters ham band. The RT246 and RT524 are alike except the 246 adds pushbutton tuning for up to ten pre-selected frequencies, and uses an external speaker since the tuning system takes up the space. It is possible for me to run a cable to the truck cab and use a remote head. Maybe for the future..
The secondary operators position sports an Alinco DX-70 with rigblaster, the RT524 and RT246, as well as the two 300-channel scanners. The terms "primary" and "secondary" don't mean anything related to importance, they are just two places to sit and operate.
RT524 radio. This set and the RT246 use a diplexer to share the same antenna on the truck's front bumper. These two radios are also connected to the VIC-4 intercom system. There are a couple of little maglites and FRS radios.
The vertical green unit is the diplexer for the RT246 and RT524. Also, note the RT246's speaker, the 9" RCA TV set, a recent upgrade from a 4" monochrome AM/FM/TV. The military speaker does not seem to affect the CRT image purity.(oooh color!!) and the 12VDC circuit breaker panel.
The panel takes 12VDC from the DC bus control panel at the front of the shelter and provides several 20A circuits for the communications radios. There is a master disconnect, a 100A breaker was used. All the DC wiring between these panels and the battreries, power supplies, vehicle, etc, were done with 6-guage wire. For those skeptical about using 6Ga wire and a 100A breaker, it will trip instantly, and it's not intended as a breaker but was convenient for a switch.
The diplexer for the RT246 and RT524. The radios need to be at least 5MHz apart according to the manual, but if low power us used, they can be a little closer. The range is about 30-80MHz with some extension at the ends.
General coverage HF receiver, useful from 500Khz to 30MHz, AM/SSB/CW. Kenwood R-1000. Of the less expensive receivers found today, this one is an excellent value.
CRT for use with a portable computer, and also note the electric heater mounted to the upper rails. It's not needed too much in Texas, but can help keep things more comfortable in cold weather.
On the curb side of the shelter, near the front corner, the DC power wiring, intercom cabling, and the secondary air conditioner conections are passed through the wall. This used to be a space for an exhaust fan.
My friend Dennis brady using the gear on Field Day. We took turns making contacts using the IC706 and the bumper-mounted HF whip (after extending it to about 25FT and laying it over into the top of a tree..)
The tree not only made a convenient termination, but also gave us an angle on the whip so we could launch some radiation at a variety of angles.
The whip is about 17FT up in that tree. Tuned up very well.

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