Bush VHF61

[PJL]

Many of the Hunts capacitors are in decoupling positions where some leakage would not prevent the set from working. However, they are renown for failing in use so I replaced all of those in my VHF61 as I planned on using it regularly. There are quite a few decoupling the heaters and if they go leaky they will overheat until they self-destruct.

[Techman]

Originally Posted by PJL

There are quite a few decoupling the heaters and if they go leaky they will overheat until they self-destruct.

Yes, but this set uses an isolating transformer, so there's virtually nothing in the way of voltage across them to cause them stress. However, in a live chassis heater string it's a different matter where a capacitor in this situation going short circuit can potentially take out half the string with valve heaters able to light up the room until they pop!

I did a little experiment with a Bush radio a while back where I lifted one end of a potentially leaky screen grid wax de-coupler and tacked in a new replacement and it made less than a volt difference to the HT screen voltage (fed through the relatively high value resistor in the circuit) and no effect on performance at all. I do accept that not all radios are the same and there are certainly cases where capacitors that become excessively leaky can pull that voltage down causing performance issues and I myself have replaced bad examples for this obvious reason, so replacing them anyway may not be a bad idea.