Some Excerpts from W2DU's Reflections 3

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W2DU:
In a previous thread, "It Was Chistmas Eve 40 Years Ago" there appeared to be some interest in the history of the early space age. Son Rick, W8KHK, present some of my work, specifically ECHO, and I posted some excerpts from Reflections 3 in Posts 28, 29, 37, and 38 in the aforementioned thread. However, the post in #38 is an incomplete diagram of the tx to antenna coupling circuit. The original complete diagram is missing.

I tried to post some additional pics, but they were to large to fit, so I have been reducing them to a postable size. Since there are several that you might find interesting I'll have to post them in separate threads.

In this post you'll find the complete section describing the development of the transmitting antenna array that flew on the World's first weather satellite, TIROS 1, a pic of the spacecraft, and one showing me making adjustments to the radiating elements on a full-scale electrically-equivalent model of the spacecraft.

In following threads I'll post pics of the matching networks that couple the four xmtrs to the antenna array. The four transmitters operate simultaneously on four different frequencies.

Walt, W2DU

WA1GFZ:
Early space for me was very interesting. As a kid you just had to feel for all the hard work when a rocket would just clear the pad and turn sideways and be blown up. I remember the family dancing in the livingroom when one finally kissed the sky.
At the same time we would get work stories from my Dad from the P&W test stands. I'll never forget the one "We have a motor that burns bunker oil." (later figured it out that it was JP7)

W2DU:
Continuing from my original post. The following pics concern the matching networks that coupled the four xmtrs to the four-monopole antenna array. The networks were designed to couple four xmtrs to the antenna array operating simultaneously on four different frequenies, with radiation circularly polarized on all frequencies. One xmtr at each frequency radiates right-hand CP and the other radiates left-hand CP, which is the nature of the outputs of diplexers, otherwise known as 'rat races'.

One pic is of the matching networks fabricated in stripline printed-circuit boards, one for 136 MHz and the other for 235 MHz. This unit is rather beat up after being shown at hamfests and ham club meetings. Another pic shows the circuit diagram of the networks, while the third shows the actual layout of the stripline. The two circuit boards are mounted together as in a sandwich, with their four output terminals connected together for feeding the four monopoles in the array. The sleeve portion is the principal radiator for the 235 MHz band, while the rod extension and the sleeve combination comprise the radiator for the 136 MHz band. More TIROS pics to come later.

Walt, W2DU

W2DU:
In the next set of pics we show W2DU on right and technician John Luzansky on the left in the antenna lab at the David Sarnoff Research Center in 1958, also showing the 4:1 scale model of one-half of the spacecraft backed by a 4 x 4 foot aluminum panel ground plane. This arrangement was used for impedance measurements (hundreds) of different configurations of the radiator to find a configuration that would yield a 50 + j0 impedance. For 4:1 scale-model measurements the frequency must be four times the operating frequency. For these measurements the signal generator was an HP-612 and the impedance-measuring instrument was an HP-805 slotted line. There were no other impedance-measuring devices available in 1958. The other devices used were the Smith Chart and slide rule--no hand calculators available either!

The next pic shows mechanical technician Herb DeCerbo attaching the W2DU antenna array to the spacecraft.

W2DU:
Still continuing, the next pic shows W2DU setting up a model of the spacecraft with an empty 3rd-stage Delta rocket, the rocket that gives the spacecraft its final push into orbit. W2DU is preparing to take radiation pattern measurement of the combination to determine whether the rocket in the near field of the antenna array will seriously affect the pattern in a way that could blackout the signal prior to orbit. It turned out that the fiberglass casing of the rocket didn't affect the radiation pattern.

The next pic shows the spacecraft atop the Delta 2 rocket at launch pad 17A. The spacecraft is at the 12th story level with the gantry pulled away.

The third pic shows the spacecraft surrounded by the nose cone, or fairing. The floor level with the gantry in place is at the 12th story. The pic shows W2DU peering into the fairing to determine whether the ends of the radiators fit properly inside the nose cone.

More pics to come.

Walt, W2DU

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