17-09-2017, 12:56 PM
(This post was last modified: 17-09-2017, 12:57 PM by Murphyv310.)
Hi.
The 1j42a single valve pantry transmitter has been a great success. There is no gain at all from the grid fed with audio and looking at the crystal oscillator on the scope the waveform is a perfect sine wave with no clipping. Feeding an audio signal into the opposite grid hardly effects the oscillator and only on the anode can the modulation be seen. I use a 1566kHz crystal and even without any anode tuning, just a 10mh choke there is virtually no second harmonic.
Since the original single valve unit I've added an input buffer using a low voltage triode, 2v on the anode and a PA using
a 1j29b at 80v via an inverter.
The 1j42a single valve pantry transmitter has been a great success. There is no gain at all from the grid fed with audio and looking at the crystal oscillator on the scope the waveform is a perfect sine wave with no clipping. Feeding an audio signal into the opposite grid hardly effects the oscillator and only on the anode can the modulation be seen. I use a 1566kHz crystal and even without any anode tuning, just a 10mh choke there is virtually no second harmonic.
Since the original single valve unit I've added an input buffer using a low voltage triode, 2v on the anode and a PA using
a 1j29b at 80v via an inverter.
