| This "Paraset" has been
made, by G3VTT Colin, as another descendent of the original design. The original
design had, for amateur radio purposes, poor band spread, switched antenna
change over and used valves of lower gain.
This version has a built in TR switch
using 4 diodes and its coverage is limited to 3.500 to 3.580 which with a
single large tuning knob gives a more than required tuning rate. The original
6SK7 valves used as detector and audio have been replaced with 6SJ7's which
give improves gain. Overall gain is more than enough and therefore a volume
control has been fitted.
The set is a joy to use with its full
break in and only development work to stabilise the detector supply voltage
is required in the future which will keep the receiver on frequency as currently
the HT supply changes as the 6V6 oscillator draws extra current on transmit.
A more effective power supply is to be constructed.
The original design of Paraset was designed
for speedy production and easy operation with a strong control station running
typically 250 watts to 10 Kw as outlined by Pierre Lorraine in his book
'Clandestine Operation'.
Although this new approach excludes the
constructor from joining another group, the excursion into a newer development
is deemed necessary considering the boisterous amateur band conditions we
now have. (Anyway no real radio constructor copies a circuit exactly, he
uses the parts to hand!) |
