11-08-2012, 01:35 PM
Hi Robert,
Sounds like a really cool way of providing the heater supply. I can't imagine I'd find such baby tfo's locally though I might try the site you mentioned - for future reference.
At this stage I'm pretty happy with the electronics. I removed the additional wiring and components related to the extra grid(s) in the 6H8 versus the 6Q7. In my case the capacitor C23 was also not present so I've fitted that. The diagram shows what I assume is an optional 300 Ohm resistor across C23 - it's shown dotted in the diagram. I have not fitted that an the set is currently paying way nicely out in the workshop on soak.
I still have the voltage anomaly; where it says -7.8V at one end of R12 I have over -17V but at the pin of the 25L6 the grid 1 bias measures -7v versus the spec'd -7.5V so I'm not going to spend to much more time on that. Nothing is unduly hot and the set has now been running for a few hours. I'll wait until you measure levels in your set
My set is consuming 445mA in total with the heater chain consuming just below 300mA. B+ is spot on at 105V.
I've started Photoshopping to build a dial image - plenty still to do there before I'm ready to print anything.
I will move on to paint those grooves on the cabinet. I've seen one up on RMorg where the grooves are painted bright white and it doesn't seem appropriate. I'll probably go with something a little less striking - an off white of some sort.
Then I'll look at making a back for it!
I can't wait to see your one up and running!
Cheers, John
Sounds like a really cool way of providing the heater supply. I can't imagine I'd find such baby tfo's locally though I might try the site you mentioned - for future reference.
At this stage I'm pretty happy with the electronics. I removed the additional wiring and components related to the extra grid(s) in the 6H8 versus the 6Q7. In my case the capacitor C23 was also not present so I've fitted that. The diagram shows what I assume is an optional 300 Ohm resistor across C23 - it's shown dotted in the diagram. I have not fitted that an the set is currently paying way nicely out in the workshop on soak.
I still have the voltage anomaly; where it says -7.8V at one end of R12 I have over -17V but at the pin of the 25L6 the grid 1 bias measures -7v versus the spec'd -7.5V so I'm not going to spend to much more time on that. Nothing is unduly hot and the set has now been running for a few hours. I'll wait until you measure levels in your set
My set is consuming 445mA in total with the heater chain consuming just below 300mA. B+ is spot on at 105V.
I've started Photoshopping to build a dial image - plenty still to do there before I'm ready to print anything.
I will move on to paint those grooves on the cabinet. I've seen one up on RMorg where the grooves are painted bright white and it doesn't seem appropriate. I'll probably go with something a little less striking - an off white of some sort.
Then I'll look at making a back for it!
I can't wait to see your one up and running!
Cheers, John
Time flies like an arrow, fruitflies like a banana!
