A fairly complex homebuilt set of the late 1920`s was found
in a very sorry state amongst a box of junk. It consisted of the
baseboard and ebonite front panel, but miraculously also most
of the components.It was all there apart from an intervalve transformer
and (perhaps)an HF choke. Needless to say,it had no valves! The
oscillator cicuit in particular was difficult to follow, being
sealed in a copper can with it`s own built-in rotary switching
for three wave bands.Only two of these were used -Medium and Long.
A "Blue Spot"moving armature speaker in a rather shabby
cabinet was also found. The speaker case and it`s mechanical unit
were renovated and a period type cabinet made.The whole is now
in good working order.
The IF of this set is around 100kHz which allows ample opportunity
for stations to appear at more than one point on the tuning scale,
also the use of separate tuning capacitors for RF and Oscillator
makes this set a "two hand" tuning job. The combination
of this and the low IF frequency effect almost turns tuning into
an art form.Volume control is by varying the voltage on the screening
grids of the first and third Screen Grid valves and is quite touchy.
