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Old 5th Oct 2019, 1:25 pm   #128
FERNSEH
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Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
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Default Re: Bush TV22 with TC184 B3 converter.

Argus25 wrote: "The output of the vertical sync/integrator is physically connected to the anode, but it acts by producing a positive pulse at the grid. So the loading on the filter RC network is affected by the impedance at the anode and what you get at the grid also depends on the frequency response properties of the transformer."

So ideally a buffer/inverter stage should be inserted between the frame sync integrators and the oscillator. A correctly shaped positive sync pulse will be supplied to the valve grid instead having been distorted by the oscillator transformer.
When transistors came along all these circuit functions could be cheaply implemented but with valves it's not only the cost of the valve that has to be considered but also the assembly time.

DFWB.
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