5FP7 project starting with the focusing coil.

[AdrianPH]

51.3 Volts peak to peak now works out to be 29.6 Volts RMS is I am reading this correct, the turns ratio staying at 2.96:1 would give a primary rms of 87.67 Volts

Number of primary turns = 87.67 /(4 x 1.15 x 12.5 x 1.46 x 6.71x10^-4)

So I would make it that the number of turns has shot up to 2,276 on the primary from 1,100.

The secondary turns would be 2,276 / 2.96 = 769 turns, stick in the efficiency bit of 1.05 and is becomes 807 turns.

If the peak secondary is 100mA then rms is 58 mA, working back to  primary side current need 58/2.96 = 20 mA rms,  Stick some extra in for losses.  20 * 1.05 = 21 mA.

If I guess that each side of a push pull amp may need, say a max of 8 to 10 mA quiescent anode current then 31 mA capacity for the primary windings.

If this is correct then even the 21mA minimum rms could be out of reach of an ECC82 double triode.

The nearest primary wire size is 36 awg that can take 35mA and is 0.127mm dia
The bobbin on the transformer is the type that has separate primary and secondary sections and the primary was quite full with 1,100 turns of 0.25mm dia wire, so trying to get a double wound primary with basically 4552 turns of 0.127mm wire could be an issue, it would be very close if I could winding it by hand.

I doubt the secondary would be an issue. with 33 awg 0.18mm wire or even if I went to 32 awg at 0.2mm dia.

I think I need an even bigger core?

Adrian