In 1970 Costas Tzezairlidis SV4CG built a unique electro
mechanical machine using two motors to achieve horizontal and vertical
scanning. He had found a motor which rotated at 960 R.P.M. which
corresponds to 16 revolutions per second, the exact speed required for
the horizontal scanning. The speed of the second motor was 1
revolution per second. The reciprocal motion was produced by a cam
through an 8:1 reduction gear. A weight attached to the microscope
pulled it back to start the next line. The microscope was focussed
sharply on the drum carrying the picture to be transmitted. Resolution
was excellent.
The 'microscope' consisted of a cardboard tube with a 13 cm focal
length lens at one end and a Philips OAP12 photo-diode at the other
with another lens in front of it. This primitive microscope produced
a picture of reasonable quality.
For reception SV4CG made a converter using the long persistence P7
c.r.t. With this set-up Costas had his first SSTV contact on 40
metres with SV1AB on February 28th 1971. After that he had many
contacts on 7 and 14 MHz as can be seen from the extract from his log.
(The special commemorative prefix of SZ0 was used by all SV stations
during 1971).