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S2 Band Signal Generator



S2 Band Signal Generator

I read somewhere in AMSAT (lost the reference) that a 2400 MHz signal
generator for the AO-40 S1 Band could be made by connecting  two, 2 watt
resistors and a 1N4005 diode in parallel across a coax connector.   In
turn the signal generator was connected to a 50 MHz transmitter running
at 2.5 watts.  The 48 harmonic of 50.0 MHz is 2400 MHz.  A caution was
to not have the signal generator touch the S Band antenna; just  close
by.

I made up a similar device and operated it in the ten meter band, and
tested my 16 turn homebrew helix  (G3RUH type) and DEM 2400-144 RX
downconverter.  I was able to get S9+ signals from the ten meter
harmonics as described below.

A ten watt, 50 ohm, wire wound resistor (RS 271-133) and a 1N4005 (RS
276-1104) were soldered in parallel across the center terminal and
mounting hole of a SO-239 panel jack (Radio Shack 278-201).  This was
connected by a two foot RG 58 coax to a Kenwood TS 570DG running at 5
watts in CW mode and placed within two inches of the helix antenna.

The helix/DEM 2400-144 RX downconverter was connected to an ICOM 821H
set to receive 145.350 MHz  (=S2 band , 2401.350 MHz) CW mode.         

The TS 570DG xmit frequencies were: (tune for best CW tone)
28 5875 MHz  (84th harmonic = 2401.350 MHz)
28.9319 MHz (83rd harmonic = 2401.350 MHz) 
29.2847 MHz (82nd harmonic = 2401.350 MHz)
29.6462 MHz (81st harmonic = 2401.350 MHz).  
All produced 10 dB over S9 readings on the 821H.  The no signal noise
was S2.

I concluded the downconverter works fine.

Barry Hawkes N1BAN
bhawkes@mediaone.net
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