09-04-2012, 11:07 AM
Last year sometime I bought an AVO Test Bridge off e-Bay. I knew nothing about these but even so it didn't seem to work.
It smelt like it had been damp and changing the wax and tar capacitors didn't seem to fix it.
I had got hold of some data but this muddied the waters further as it showed a different valve and mine also had a Westector which wasn't on the diagram.
Given my level of knowledge at that point I put it aside pending education and at least it would fully dry out in the interim.
I had another go at it a few weeks ago as I was then able to apply at least a modicum of scientific method to proceedings.
The first thing I did was check the HT voltage and found it was only 40V. I double-checked that I was measuring the right thing and noticed a waxie I'd missed lurking in the muck which wasn't on the data. Changing this seemed to sort it out nicely.
I was given some more comprehensive data for a chap 'over the wall' and this explained that they were introduced in 1936 with an L63 valve (as mine has) but in 1941 this was changed to a 6B8G. Why mine is dated 1943 remains a slight mystery.
It seems accurate but I'm waiting the chance to check it against either Alan or David's cap meters before passing final judgement.
- Joe
It smelt like it had been damp and changing the wax and tar capacitors didn't seem to fix it.
I had got hold of some data but this muddied the waters further as it showed a different valve and mine also had a Westector which wasn't on the diagram.
Given my level of knowledge at that point I put it aside pending education and at least it would fully dry out in the interim.
I had another go at it a few weeks ago as I was then able to apply at least a modicum of scientific method to proceedings.
The first thing I did was check the HT voltage and found it was only 40V. I double-checked that I was measuring the right thing and noticed a waxie I'd missed lurking in the muck which wasn't on the data. Changing this seemed to sort it out nicely.
I was given some more comprehensive data for a chap 'over the wall' and this explained that they were introduced in 1936 with an L63 valve (as mine has) but in 1941 this was changed to a 6B8G. Why mine is dated 1943 remains a slight mystery.
It seems accurate but I'm waiting the chance to check it against either Alan or David's cap meters before passing final judgement.
- Joe
