OK, I understand. The numbers 2V1, 2V2, 2V3 etc were just valve numbers, there is a list of them on the first diagram for unit 2, which is the modulator.
2V1= CV131 = EF92
2V2= CV136 = EL90
2V3, 2V4 = CV133 = EC90.
The transformer 2T2 ended up being faulty as open circuit, probably due to the wire being very fine and corroded. So I went similar to the classic Mullard amp circuit with an ECC83 Schmitt Phase circuit driving the two EC90's. Actually using CV4058 which is a more modern replacement for the CV133.
In the aircraft radio that this is from the mod stage drives the anode and screen of the TX output valve and the screen of the driver valve. I had assumed that the output of the mod stage would have been approx 5 Watts as that was the output of the radio at 130 MHz but I can not achieve anything like that, although I am driving the output into 11K resistive load I can only get a 200 Volt swing. So I need to do more reading and figuring out.
But I am still playing with the circuit as I have it built, still to complete the compression part.
Adrian
2V1= CV131 = EF92
2V2= CV136 = EL90
2V3, 2V4 = CV133 = EC90.
The transformer 2T2 ended up being faulty as open circuit, probably due to the wire being very fine and corroded. So I went similar to the classic Mullard amp circuit with an ECC83 Schmitt Phase circuit driving the two EC90's. Actually using CV4058 which is a more modern replacement for the CV133.
In the aircraft radio that this is from the mod stage drives the anode and screen of the TX output valve and the screen of the driver valve. I had assumed that the output of the mod stage would have been approx 5 Watts as that was the output of the radio at 130 MHz but I can not achieve anything like that, although I am driving the output into 11K resistive load I can only get a 200 Volt swing. So I need to do more reading and figuring out.
But I am still playing with the circuit as I have it built, still to complete the compression part.
Adrian
Learning as I go!
Youtube EF91 Valve
Youtube EF91 Valve
