06-05-2012, 10:35 PM
Another update on the regen detector, found a 6J5 triode today so rewired the valve base to take that, it works a lot better than the 6AC7, managed to get the 550 khz tuning range from 2.45 to 3.05 mhz but using quite a low L/C ratio by removing 6 turns off the coil and putting a 270 pf in parallel with it, the 400 pf tuning capacitor in series with a 220 pf is also connected across the coil. Regen can now be obtained across the whole of the above tuning range whilst maintaining a low L/C ratio.
There is no pulling at all when tuning the mixer grid and very little when going in and out of regen on SSB/CW.
Regen starts with an anode voltage of around 22 volts with full oscillation at around 30 volts, it seems to be very drift free once warmed up.
Whilst receiving an SSB transmission there was almost no shift of pitch when altering the receivers HT plus & minus 20 volts above and below it's 200 volts. design voltage. Regen is now obtained by varying the det anode voltage via a pot. divider across the HT. The audio output from this det. is slightly less than the previous arrangement but it's still ample for the triode pentode O/P stage.
I think I have just about gone as far as I can go with the det. arrangements, circuit wise I am happy with it for the moment, ideally though I would prefer a B9A or B7G valve for it if I can find one with similar characteristics as the 6J5.
Lawrence.
There is no pulling at all when tuning the mixer grid and very little when going in and out of regen on SSB/CW.
Regen starts with an anode voltage of around 22 volts with full oscillation at around 30 volts, it seems to be very drift free once warmed up.
Whilst receiving an SSB transmission there was almost no shift of pitch when altering the receivers HT plus & minus 20 volts above and below it's 200 volts. design voltage. Regen is now obtained by varying the det anode voltage via a pot. divider across the HT. The audio output from this det. is slightly less than the previous arrangement but it's still ample for the triode pentode O/P stage.
I think I have just about gone as far as I can go with the det. arrangements, circuit wise I am happy with it for the moment, ideally though I would prefer a B9A or B7G valve for it if I can find one with similar characteristics as the 6J5.
Lawrence.
