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Old 10th Jul 2006, 1:57 pm   #1
Neil Purling
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 1,968
Default Regarding home made TRF

I made my radio with a mixture of circuits: The 'Electron Coupled' design from member heatercathodeshort, the audio stage adapted from Radio for Boys by E.N. Bradley (1952).
The audio stage is a 6J5 Triode feeding a 6V6.
I get the impression that it could be louder, as I seem to have some travel left on the volume control.
Now I was interested to substitute a 6SN7GT double triode and have the first section give a fixed gain of a factor of two or three. I have no idea of what sort of signal level the detector will give when it is on the point of oscillation.
Ideally I want the strong local signal to just drive the 6V6 just into distortion as the detector breaks into oscillation, assuming the volume control is at ful.

If Isoplethics ever come out with a range of plug in coils beyond the basic Long & Medium Wave ones that is going to be the cue for yet another makeover.
If I adapt the radio to cover Short Waves I would change the detector to a EF91 if that would be better to cover the Short Wave broadcast bands.
Well, that's summat for the longer evenings....
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