Introduction
The project has been started with the following purposes:
to be challenging enough to provide stimulus during many years
to require design skill
to require a number of home made equipment
Goals
These are the goals:
to achieve reliable 2 way communication using the most suitable digital mode.
To be able to work stations in four continents: Europe, America, Asia, and Australia.
Basic design
The band chosen is 70 cm (432 MHz). Reasons are:
the antenna system can be reasonably compat. It can be implemented with off-the-shelf products
without the need of home made mechanical construction, for which I have limited tools and skills.
There are many stations active, even if not as many as in the 2m band.
Components construction is challenging but still it does not require microwave tecniques (and related
mechanical work).
Slower Faraday rotation was not considered since one of the choises was to use circular polarization.
Tranceiver
I will start using a Kenwood TS-2000 located in my shack connected to a laptop running the decoding
software.
Power amplifier
Homebrew 500 W amplifier based on commercial pallet. To be located at the base of the antenna for
efficiency and because I hold a pacemaker that does not like stray electromagnetic fields.
Antenna system.
AltAz rotator: YAESU 5500 with remote control. Two circular polarized yagys for a gain of 20 dBi.
Preamplifier
Commercial preamlifier with NF < 0.3 dB Further preamplifier in the PA box with NF < 0.5 dB.
Connections:
From shack to box at the base of the antenna: existing RG-8U.
From box to various components and antenna: LMR-600
AltAz rotator control: XBEE high power modules.
Connectors: N and SMA.
Instrumentation
At least the following tools are supposed to be required:
UHF SWR Analizer (Commercial).
Dummy load 500 W intermittent and swr < 1.1 @ 500 MHz (Commercial).
Noise generator (Homebrew).
Calibrated attenuator for measurement using the tranceiver (Homebrew).
RF probe to be used for measuring power (Homebrew).
