[Milsurplus] Propagation exercise

[Cletus W Whitaker]

de WB2CPN South Central Pennsylvania 2004.01.05

Part 2 0f 2

About the time you mention, I was in the USAF AACS,
and worked the HF Receiver facility at Andrews AFB,
Maryland.  We were testing such a device as you mention,
except it didn't shoot straight up.  Our receive
antennas were Class "A" Rhombics, and their
transmission line was 4-wire open-wire low loss.
The device was in a black 19 1/2 cabinet about
5 feet tall.  It contained a 5 KW peak pulse short
duration transmitter and a companion receiver.
Like RADAR except the RF frequency was stepped
within a range of test freqs.  There was a
syncroscope in the rack that indicated distance,
and a rotary switch to select the transmitter
frequency to be displayed.  The transmitter would
send a pulse of RF into a rhombic aimed at, say 52
degrees azmuth, and the receiver would listen for
echoes to display on the scope vertical.  The theory
was that the signal would leave our station, visit
the "E" or "F" or whatever at the time, bend down and
be reflected from the ground, then back up again, and
down again, and so on.  What we wanted to see was
the backscatter every time it got bent in the ionsphere
or bounced against the ground.  Yes, we did get some
good pictures on our crude scope camera.  We didn't
try to understand it, we just collected the data and
carried it down the street to Hq AACS.  Also, We had
the earliest I ever saw 4-chan HF SSB between us
and Newfie.

73  Clete