ONE VALVE HF RIG
Here is a really simple design that I have built and tested myself.________It is a classic one valve design
The output power depends on the HT voltage and valve used.________Either a 6V6 or 6L6 type can be used they are both beam tetrodes.
The 6L6 will give most power but to realise it the HT voltage will have to be increased to around 600V, as I have not tried out the valve with this HT level I cannot say for certain what the power would be but it has been suggested it may be around the 30W mark.
The example I have built and tried used a 6L6 with 275V ht and it is putting out around 9W as measured on my commercial power meter
The coil L1 was wound from 22swg wire wound on a 5cm length of 22mm plastic water pipe. I used 30 turns to tune the 3.5 MHZ crystal.
The choke needs to be about 2.5 millihenries
The capacitors should be rated at least 350v working (subject to HT voltage used)
Perhaps surprisingly the valve is not hard to obtain try COLOMOR ELECTRONICS
Web address www.colomor.demon.co.uk
The mains transformer is a MAPLIN item_______ code_____XP27E