05-06-2017, 11:28 AM
We're coming up to the restoration of the timebases. The oscillators are known to be working and are supplying sawtooth drive waveforms to the grids of the output valves. The only modification the timebase circuits received was the addition of the double-diode interlace filter which took the form of a separate module which employed an EB91 double-diode. The circuit of this unit is similar to the Pye "positive interlace filter". In fact the circuit was not unique to Pye and was also used in the Pilot CV34.
The interlace unit was removed during the initial stages of the assessment of this receiver, it can be reintroduced later but instead of using the EB91 double-diode the existing D63/6H6 valve can be used instead.
As mentioned earlier an external 6.3 volt transformer will supply the timebase valve heaters, much safer than employing the transformer in the receiver which also supplies the EHT. Don't want 4KV cables swishing about while working on the set.
Geordie McBoyne.
The interlace unit was removed during the initial stages of the assessment of this receiver, it can be reintroduced later but instead of using the EB91 double-diode the existing D63/6H6 valve can be used instead.
As mentioned earlier an external 6.3 volt transformer will supply the timebase valve heaters, much safer than employing the transformer in the receiver which also supplies the EHT. Don't want 4KV cables swishing about while working on the set.
Geordie McBoyne.
