Jason Kit W11 Wobbulator
|Service Data||Yes, Thanks to Ed Dining.|
|Condition||Good - untested. I suspect that the three small knobs are not original.|
|Dimensions||11.5" x 5.25" x 7" (287 x 130 x 175mm)|
|Comments||A wobbulator is a special type of signal
generator, also known as a sweep generator, or sweemar,
which generates a signal of changing frequency, a sort of
wideband FM. They are used, along with an oscilloscope,
for aligning filter circuits. The X axis of the 'scope is
synchrinised with the rate of change of frequency, and
the Y channel displays the output of the circuit under
test (using a detector circuit, if needed), so that the
'scope shows a graph of ouput voltage against frequency.
It is then quite easy to align the circuits for the
correct response, and to make sure that the response is
even, and not distorted in places.
This unit covers 0 to 83 MHz (0 to 2.2MHz, 0 to 40MHz and 35 to 85MHz), in three bands, and uses three valves (EZ80, ECC81, ECH80). It has an option for feeding in a marker signal of known frequency (this will show as a "pip" on the display), and gives out a 50Hz signal to synchronise the 'scope. The oscillator unit is built onto a large ceramic turret switch, which makes it almost impossible to trace the circuit!, but should make the signal fairly stable. This covers the common IF frequencies for radio and television, and the Band 1 TV channel frequencies (I suspect to allow the re-alignment of older sets with TRF type receivers, as the Band 3 sets would be superhets, and so the alignment would be at the (lower) IF frequency).
Jason also supplied a number of kits for VHF FM tuners, their first, in the mid 1950's, was a kit form of the "Wireless World" FM tuner, using four EF91's in the basic version and 5 in the fringe version.
Copyright J.Beacon & M.Wroe-Parker 2003