Question about voltage for detector valve

[Nowhere-Man]

I could do with a bit of advice about the HT and GB voltages for valve 1 in the attached circuit – a three valve battery powered TRF with reaction.

The valves from right to left are:

V3 (Output) = P220A
V2 (L.F.) = L2
V1 (Detector) = HL2

The construction notes for the receiver (a Telsen Conqueror 3) shows three HT values but suggests running the HT together for V3 and V2 and set at 120V. At this voltage the recommended GB for V3 is -9V and for V2 is -3V. So far so good, but the construction notes gives no recommendation for the voltages to be applied to V1, the HL2 detector. The maximum operating conditions for this valve are 150V on the anode and -3V on the grid. If I interpret the circuit correctly there is 0V GB on the valve, so at what voltage should I set the HT? If 120V is reasonable then why was the circuit designed with three separate HT connections!

Nick

I lack the time to go too deeply into this but what is your detector tube? If it's a TRF, I guess it's probably a pentode with a grid leak? Is it steep slope? Sure, the bias may be around - 5 fixed, for example, but the signal if it's 2 volts will give you -3 on the grid (positive cycle) and - 7 (negative cycle). The anode voltage will be at H.T. as the amplifier but there may be a resistor leading to the anode?

Sometimes details aren't clarified in schematics which can be an obstacle. Perhaps a similar schematic of a similar radio will help you compare?