Re: Racal RA17L BFO behaviour
Thank you Al.
I overhauled the entire unit as you suggested, but no improvement! I replaced every component including the valve with a NOS EF91. The unit uses a CV4014, this must be an equivalent of the CV138.
All the components were within spec. The only original elements are now the L and the two variable capacitors. The ohmic resistance of the L is 112+8, so no shorts apparently.
Actually the "worst" signal seems to be at the cathode: the 100kHz wave is superimposed by some very irregular, higher frequency oscillation. At the anode it is definitely a square wave, very flat at the top.
Now I will go through a deeper inspection, including bad wires/contacts...
Paolo
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