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Re: early satellite history



----- Original Message -----
From: "Ronald Long" <rlong3@columbus.rr.com>
To: <amsat-bb@amsat.org>
Sent: Sunday, November 18, 2007 11:19 PM
Subject: [amsat-bb] early satellite history
>
> Here is a very interesting article about the development of Echo, the
> balloon satellite, also written by Pierce.
> http://www.smecc.org/john_pierce___echoredo.htm
> I remember when we at Ohio State recorded President Eisenhower's
> message relayed by Echo. I have lost the tape, however.
>
> ron

Hi Ronald, W8GUS

Tank you for your information because the story of ECHO-1A launched
on 12 august 1960 was a very "amarcord" for me.

ECHO-1A was also equipped with a VHF beacon on 108.00 and 108.03 MHz
and I was receiving both signals using a homebrewed converter with two front
end low noise triodes 6AN4 in cascode and a 1/2 6J6  as a mixer and a 6C4 as
kathode follover.

The local oscillator was a 6.66972 MHz xtal in to a 1/2 12AT7 and the other
1/2 12AT7 was used as a duplier at 13.33944 MHz

The other 1/2 6J6 of the mixer was used as a multiplier by 5 getting 66.6972
MHz for the local oscillator.

Finally 108.00 - 66.6972 = 41.3028 MHz was the IF in to a Hallicrafters
SX-28 receiver used with  BFO ON

At that time I was not aware on how to measure the noise figure of my
converter and the trick to adjust the input of the first 6AN4 for the lowest
generated noise was to adjust the antenna coupling while tuning L and C
of the input stage for the strongest received noise from the sparks of a
near by car.

By the way both signals at 108 and 108.03 MHz where very well received
using only a 5 elements yagi aimed by hand with easy because ECHO-1A was
visible by naked eye during the night until the batteries of the beacon
lasted.

At that epock time in 1960 the 108 MHz band was not used to broadcast FM
in Italy and it was completely free of man made noise.

In my town the only noise piked up by the antenna was about 290 kelvin from
the ground at 108 MHz so that  the noise emitted by our galaxy was received
in loudspeaker aiming the antenna toward the milky way.

Actually if I put a finger in to the N connector of my spectrum analyser and
I tune the 108 MHz band I receive a lot of FM signals at least 10 to 15 dB
over the analyser noise !

In a separate email I will send to you the schematic diagram of this type of
low noise converter.

Best 73" de

i8CVS Domenico




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