05-10-2016, 07:59 PM
Thanks Mike for the links
Thanks too to Andy.
A few years ago I made a one valve radio with Ferrite rod aerial and a Rod Pentode, it featured reaction but I found that if you tailored the HT volts to around 30v you could dispense with the reaction control (either cap or variable resistor) as the valve would self limit, like an AGC feature, it would always sit at the point of oscillation, it would throttle back on strong signals but the gain would rise on weak stations. Higher HT and the circuit would take off, lower HT and the reaction would stop.
Regarding using a valve detector in a crystal set circuit, I've never had a result like today, I did get some success but only on a really strong signal, I find that I can hear stations not audible with a germanium diode, OK it's not a proper crystal set as I'm using power for the filament but I'm amazed.
I did also try varying the filament volts, I got results at 0.3V full volume at 0.7v with no change to the max of 1.2v
Thanks too to Andy.
A few years ago I made a one valve radio with Ferrite rod aerial and a Rod Pentode, it featured reaction but I found that if you tailored the HT volts to around 30v you could dispense with the reaction control (either cap or variable resistor) as the valve would self limit, like an AGC feature, it would always sit at the point of oscillation, it would throttle back on strong signals but the gain would rise on weak stations. Higher HT and the circuit would take off, lower HT and the reaction would stop.
Regarding using a valve detector in a crystal set circuit, I've never had a result like today, I did get some success but only on a really strong signal, I find that I can hear stations not audible with a germanium diode, OK it's not a proper crystal set as I'm using power for the filament but I'm amazed.
I did also try varying the filament volts, I got results at 0.3V full volume at 0.7v with no change to the max of 1.2v
