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Old 8th Jun 2008, 9:36 pm   #5
paolo67
Retired Dormant Member
 
Join Date: Jun 2008
Location: Milan, Italy
Posts: 15
Default 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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