[Premium-Rx] Military gear

[Michael O'Beirne]

Good evening guys,

I am not sure whether Larry has worn green camo kit and a steel helmet and 
spent miserable hours in a muddy trench awaiting an "enemy" dawn attack, but 
I can tell him that some military gear suffers physical and RF abuse that I 
would be most reluctant to inflict on any amateur gear.

For those who like numbers, here is an extract from an MOD catalogue of 
about 1978 for the Clansman VRC353 VHF transceiver.  The environmental spec 
is based on British Def Spec DEF133 Table l3 for tactical gear:

Frequency stability
TCXO maintains the selected operating frequency within 5 ppm at any ambient 
temperature down to - 40 deg C.

Immunity to interference
The extremely high selectivity and low temperature radiation allows the set 
to be separated in frequency by only 5% and with antennas 2 metres apart to 
be operated on full power with negligible mutual interference. [Typically 
two sets in the same LandRover].

Receiver protection
No damage will be caused by a signal on the antenna terminal of 50V emf via 
50 ohms continuously at any frequency within the tuning range, or 100V for 1 
second.

Environmental spec
Ambient working temperature from -40 deg C to +55 deg C.
Designed to meet operational conditions in wheeled and tracked vehicles, 
travelling on surfaced and unsurfaced roads and open country, and transport 
by land, sea and air.
Withstand operational shocks in armoured fighting vehicles due to the impact 
of non-penetrating shells on the vehicle armour and delivery by normal 
parachute techniques.
Capable of operation under conditions of heavy driving rain, salt spray, 
high wind, driving dust and snow and humidity in excess of 95%.
The equipment can be operated and stored at altitudes of 2,500 metres and 
can be transported in unpressurised aircraft at 8,500 metres.
Can withstand immersion to a covering depth of 1.6 metres for at least 2 
hours.
Is immune to the corrosive effects of acid spray from secondary batteries 
and is unaffected by severe contamination by fuel oils, hydraulic oils and 
lubricated fluids.

I remember operating full duplex FSK HF links on about 5 MHz with a Tx/Rx 
frequency separation of around 200kHz, a Tx output of 250W and an antenna 
separation varying from about 30 metres to about 8 metres, and working the 
links too, albeit with old valved gear designed by Marconi initially for 
ships with lots of analogue pre-mixer selectivity.
73s
Michael
G8MOB