Amateur Television (ATV)
A primitive 23 cms
(1300MHz) ATV system has been set up which comprises a Comtech
23cms transmitter and receiver for analogue transmissions and a
satellite TV Comag SL55 for digital transmissions. The Comtech
transmitter power is raised to 1 watt in a Comtech amplifier and
that in turn drives an aged solid state 15watt PA comprising a
Mitsibishi module. The antenna is a 32 element quad loop yagi
with a mast head preamp. It is cut for 1296Mhz and is not optimum
for the ATV band so there is room from improvement here.
With this set up I can
work throught the analogue repeater GB3IV
TV repeater on the Isle of Wight with reasonable results (See picture
below). The repeater output frequency is 1316Mhz.
A 3cms (10GHz) analogue input is now proposed for this repeater so a 13cms Tx module has been purchased with a view to using a G8ACE X4 multiplier to get to 10GHz with suitably reduced deviation on the 13cms Tx. The set-up is shown below. To operate at the home QTH it is proposed to mount the X4 module and a 1Watt PA up the mast behind a 19 inch diameter dish. The 2.5Ghz feed to the X4 module will be in the shack and the 2.5G fed up to the X4 by low low coaxial cable.
Excellent digital signals from the site of the proposed GB3SQ repeater in Bournemouth have also been received at a distance of ~24km (See below). Frequency is 1311 Mhz, Symbol rate: 4000 and FEC 1/2.
This was received using a cheap Comag SL55 digital receiver (shown below) of the type sold for caravan and camping installations.
