Radar equipment with 2x 8012
This is the RF section of the
AN/APQ-9 (the "Carpet III" jammer) radar countermeasures transmitter.
It uses two 8012's as a push pull oscillator, with tuning achieved by
varying the width of the plates between them. It operated between 475
and 585MHz and was used to jam the German Wurzburg gun laying radars by
radiating wideband noise. The 8012's were modulated by a pair of 807's
that in turn were driven with a wideband noise signal generated by a 931A
photomultiplier excited by a filament lamp.
|The front panel has several
controls that act mechanically on the RF circuitry; see pictures below
for futher descriptions of these. The rectangular hole top right probably
had some form of mechanical counter as a there is a gear wheel just
behind connected to the Tuning control. The Lock lever acts on this,
preventing the Tuning control from being moved. The Xtal contains
a 1N22 crystal detector.
In the above picture the cylindrical units to the lower left and right
have sliders which are adjusted by the Tuning control. At the bottom left
can be seen the crystal detector housing above the Antenna connector.
In the above picture, the Antenna Matching control adjusts a slider in
the square section. The gear-wheeled control is the Tuning control. The
control that can be seen above the transformer is used to move one of
the 8012 valves closer or further away from the centre of the RF circuitry,
see below. Some components are missing but it appears that the coaxial
cable that connects to the Antenna socket on the front panel connects
to the square section at the left as in the above picture.
Closeup of the 8012's, one
fitted and one removed. The Antenna Coupler control causes the rod running
across the middle of the picture to move the coupling loop, centre, in
and out. Adjusters inside the unit move the valves towards or away from
the central RF circuit. The Tuning control moves the flat fingered metal
components in the centre of the picture apart.