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mister valve · 27th May 2018, 5:14 pm

I assume that 'Radio 5' has a 909kHz 'Tx' near to you ? So is a strong signal, that is probably why you can tune it in.

This sounds like a classic case of the tuned circuits being badly out of alignment (as 'Boater Sam mentioned). Changing the 'Mica' caps in the tuned Circuits (R.F & I.F) will almost certainly detune them.

As mentioned above, Mica Capacitors (Condensers) are very reliable and normally retain their correct capacitive values and internal insulation so rarely need changing. But do change all the Paper Capacitors "waxies" regardless of condition, they will by now be in varying states of electrical leakage (particularly 'THAT' Capacitor which signal couples the Anode of the 'EBC33' to the Control Grid of the 'EL33'. The 'EL33' Valve is a high slope Pentode, so even the tiniest leakage of 'THAT' Capacitor can cause the EL33 Valve to run to saturation point - thus passing excessive current. This can cause the output Transformer and/or the Cathode bias resistor to burn out. Even the Mains Transformer and 'AZ31' rectifier could become casualties.

27th May 2018, 5:14 pm	#5
mister valve Hexode Join Date: Aug 2009 Location: Blackpool, Lancashire, UK. Posts: 311	Re: Radio Rentals Model 58 I assume that 'Radio 5' has a 909kHz 'Tx' near to you ? So is a strong signal, that is probably why you can tune it in. This sounds like a classic case of the tuned circuits being badly out of alignment (as 'Boater Sam mentioned). Changing the 'Mica' caps in the tuned Circuits (R.F & I.F) will almost certainly detune them. As mentioned above, Mica Capacitors (Condensers) are very reliable and normally retain their correct capacitive values and internal insulation so rarely need changing. But do change all the Paper Capacitors "waxies" regardless of condition, they will by now be in varying states of electrical leakage (particularly 'THAT' Capacitor which signal couples the Anode of the 'EBC33' to the Control Grid of the 'EL33'. The 'EL33' Valve is a high slope Pentode, so even the tiniest leakage of 'THAT' Capacitor can cause the EL33 Valve to run to saturation point - thus passing excessive current. This can cause the output Transformer and/or the Cathode bias resistor to burn out. Even the Mains Transformer and 'AZ31' rectifier could become casualties. __________________ If you live, the chassis was dead; if you're dead, the chassis was live !!!!