20-04-2020, 05:21 PM
Hi.
Here is the circuit I'm using for a shortwave pantry TX.
Virtually any valve radio audio output transformer will do. Even a little MP3 player gives enough drive, remember this circuit is flea power but it works very well on short wave. Some experimentation will be needed for the tuning coil.
Aim for 1.1 volts on the valve filament. B2 a PP3 should last for a very long time, I use a rechargeable.
The 1J42a oscillates happily up to 18mhz and could well go more but 18mhz is the highest xtal I have.
Here is the circuit I'm using for a shortwave pantry TX.
Virtually any valve radio audio output transformer will do. Even a little MP3 player gives enough drive, remember this circuit is flea power but it works very well on short wave. Some experimentation will be needed for the tuning coil.
Aim for 1.1 volts on the valve filament. B2 a PP3 should last for a very long time, I use a rechargeable.
The 1J42a oscillates happily up to 18mhz and could well go more but 18mhz is the highest xtal I have.
