Re: Bush TV12/TV22 differences
The TRF models had to be stable all the coils were tuned to the transmitter frequency, plus or minus a little to give the necessary vision bandwidth. The TV12A was made for Alexandra palace, the only transmitter operating then. 45Mhz vision and 41.5 Mhz sound only they were Mc/s in those days.
Most of the TV's I worked on in the early days were TRF's.
Peter
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