Practical Wireless Transistor Tuner/Converter
The Transistor
Tuner/Converter described in the August 1964 issue was a one, two or
up to five transistor frequency converter
It was in effect the
front end of a normal radio set, with a traditional Denco Blue coil
front end RF tuned circuit , tuned by VC1
This fed a to the Base
of the first OC171 (Tr1) and amplified and the signal appeared at the
collector
and tuned again the the
Denco Yellow coil with VC2
the output of this
yellow coil is fed to base of the next OC171 (Tr2)
If
you note Tr2 is also wired with a third Denco coil this time a white
oscillator wired in a Self oscillating mixer circuit
Here's
a clue, instead if changing the base current to make the transistor
oscillate, The Output from the collector is fed back to the emitter
to change that
This
mixer oscillator OC171 (Tr2) runs at 1.6 Mhz and the base of this
transistor is fed with the received signal the frequency the
converter is tuned to, the two mix and hey presto the out put appears
this
can be fed directly to a Medium wave radio tuned to the converters
output
As with all mixers a
number of other mix frequencies appear at the out put car has to be
used to tune the Medium wave radio to the correct one
One set back of this
set is the coils fitted were 3T range about 1.6Mhz to 5.5Mhz to cover
the Long wave all the way to 10 mtrs the builder needed to purchase 5
ranges of coils and it cost a lot of money.
N.B
Denco made two types of
Oscillator a White 1.6Mhs +- and Red 465Khz to run with each coil set
except there was no
specifically made 1.6 Mhz Osc coil for the lower 1T range
Denco made a range of
IF transformers again for 1.6Mhs +- and 465Khz
yes after changing a OC171 (leaky ) to a spare AF116 I had it works well
now part of my collection
