17-09-2017, 11:24 AM
There was one radio for the Forestry people. Everything else was military or for space.
Many used a pair of germanium transistors and primitive switch mode/inverter with multiple HT as the G2 can reliably work off a single series resistor (the current varies too much and almost mirrors anode current) so either multiple HT (battery taps or transformer) or two resistors as a potential divider.
Batteries were either NiCd (hence 1.2V rather than dry cell 1.4V) or rechargeable silver zinc.
Some of the high power tubes and short life specifications are the "radar" in shell, bomb and missile proximity fuzes. The USA sub-miniature tubes later used in hearing aids (like DL64 etc) are mostly simply miniature versions of B7G types with metallised paint instead of the internal metal shield. There are a couple of interesting USA 1.4V mixer/oscillator tubes/vales used in pocket sized US and Japan plastic MW only radios. Usually 1 x D cell, a 45V or 67V PP3 style HT(but longer) and DL92/DL96/DL94/3V4 etc sole B7G as audio out. No European or Russian models like that.
Many of the 60V and 90V Russian rod tubes can amplify or oscillate with as low as 0.7V LT. Or you can at minimum 1.15V LT, have useful operation down to about 18V (Not 2 x PP3 as that has an end point of about 11V, you'd want a minimum of 3 x PP3. Four PP3 and using a tap for G2 is good. As low as 12V is possible, but performance is poor.
An oscillator fed to G2 gives best mixer performance. Driving G2 direct from anode of separate valve as triodised oscillator works. Always tie g3 to f- (for g2 tied to anode)not to anode as with DF91 / DF96 / DF97 etc triodised mode.
They are all sharp cutoff. The Dual grids are not like dual gate FETs, but you can simulate remote cutoff. On the regular Rod Pentodes, use G2 for high level AGC (20V to 60V if HT is 90, or even 25 to 55) as is done for "RF Gain" on the Hallicrafters S72 .
Many used a pair of germanium transistors and primitive switch mode/inverter with multiple HT as the G2 can reliably work off a single series resistor (the current varies too much and almost mirrors anode current) so either multiple HT (battery taps or transformer) or two resistors as a potential divider.
Batteries were either NiCd (hence 1.2V rather than dry cell 1.4V) or rechargeable silver zinc.
Some of the high power tubes and short life specifications are the "radar" in shell, bomb and missile proximity fuzes. The USA sub-miniature tubes later used in hearing aids (like DL64 etc) are mostly simply miniature versions of B7G types with metallised paint instead of the internal metal shield. There are a couple of interesting USA 1.4V mixer/oscillator tubes/vales used in pocket sized US and Japan plastic MW only radios. Usually 1 x D cell, a 45V or 67V PP3 style HT(but longer) and DL92/DL96/DL94/3V4 etc sole B7G as audio out. No European or Russian models like that.
Many of the 60V and 90V Russian rod tubes can amplify or oscillate with as low as 0.7V LT. Or you can at minimum 1.15V LT, have useful operation down to about 18V (Not 2 x PP3 as that has an end point of about 11V, you'd want a minimum of 3 x PP3. Four PP3 and using a tap for G2 is good. As low as 12V is possible, but performance is poor.
An oscillator fed to G2 gives best mixer performance. Driving G2 direct from anode of separate valve as triodised oscillator works. Always tie g3 to f- (for g2 tied to anode)not to anode as with DF91 / DF96 / DF97 etc triodised mode.
They are all sharp cutoff. The Dual grids are not like dual gate FETs, but you can simulate remote cutoff. On the regular Rod Pentodes, use G2 for high level AGC (20V to 60V if HT is 90, or even 25 to 55) as is done for "RF Gain" on the Hallicrafters S72 .
