...
The photo of one guy's receiving antenna on the front of the magazine
("QST"?) shows the dish as big as his house. And "steered" with
two junker car chassis running on a circular track. I'm sure most
hams use more modest receiving antennas, but only by means of
blasting the moon with hundreds (thousands?) of watts.
The date of the photo might be crucial.
The first amateur moonbounce took place in 1953 (the first moonbounce
ever, by the US Signal Corp, was in 1946), though they never tried
to contact anyone (obviously); they just hear their own signal back
from the moon.
That was before parametric amplifiers (Sam Harris is credited with
making the first practical paramp, he was a ham and did moonbounce),
and transistors. They had to use either fairly noisy diode mixers
(I forget what frequency they used) or fairly noisy tubes in the front
end. I suspect the transmitters were fairly effective, but still
they likely needed every bit of ERP they could get.
And large antennas had to be the norm in the old days. Not many doing
moonbounce, and still not so great receivers. I'm not sure how many put
their equipment right at the antenna, rather than facing the losses
of the feedline.
But once enough got on with those big antennas, and other factors improved,
it became easier for others to do it. A guy in Australia did it
in the sixties from Australia, and they had something like a 150watt power
limit. But, he had a lot of space on the farm, and he had big rhombics.
I thought he had a section to allow some directing, but basically he
could only do moonbounce when the moon was in the right place for
the antenna.
When Sam Harris started working at Arecibo, he worked it so they
used the antenna for moonbounce one or two times in 1964 or so.
That thing had so much gain that it made moonbounce feasible for
a lot of people during the brief time it was tried.
So there's a balance. The guys with the big arrays enable people
with much smaller systems to do moonbounce.
Along the way, the receivers got better. First, they used
paramps, and then solid state devices started getting better.
I remember one review of a fairly early FET converter, and
the writer said it compared well with his 416 (or was it a 417?)
converter, and the 416 was considered basically the best front
end tube for VHF/UHF at the time. He admitted that it meant
his tube converter needed adjusting, but considering there was
no finicky adjustment of the FET converter, it bode well for
the future.
So if someone wants to hear their own echo at this point, they may
find they still need a fairly good system. But because there
people with good systems, others can get by with less.
Michael
