Amateur Television (ATV)
Some years ago a primitive 23 cms (1300MHz) ATV system was set up comprising a Comtech 23cms transmitter and receiver for analogue transmissions and a satellite TV Comag SL55 receiver for reception of digital transmissions. The Comtech transmitter power was raised to 1 watt in a Comtech amplifier and that in turn drove an aged solid state 15watt 1296MHz PA comprising a Mitsibishi module. The antenna was a 32 element quad loop yagi with a mast head preamp. It was cut for 1296Mhz and was not optimum for the ATV band so there was room from improvement here.
With this set up I could work through the analogue repeater GB3IV TV repeater on the Isle of Wight with reasonable results (See picture below). Unfortunately the site was lost to mobile phone operators and I can no longer access the new site at HMS Mercury.
With this set up I could work through the analogue repeater GB3IV TV repeater on the Isle of Wight with reasonable results (See picture below). Unfortunately the site was lost to mobile phone operators and I can no longer access the new site at HMS Mercury.
A 3cms (10GHz) analogue input was proposed for this repeater so a 13cms Tx module was 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 at the left.
Excellent digital signals from the site of GB3SQ repeater in Bournemouth have also been received at a distance of ~24km as this picture on the right shows. Frequency is 1311 Mhz, Symbol rate: 4000 and FEC 1/2.
The picture above was received using a cheap Comag SL55 digital receiver shown here, of the type sold for caravan and camping installations.
