(31-07-2016, 08:23 AM)Murphyv310 Wrote:(31-07-2016, 02:21 AM)Nick Wrote: If it's not already got UL output transformers, that's going to cost a pretty penny on its own...
The early WAD KT88 designs were often heavily modded, sometimes by folk who didn't have a clue. There's a lot of information out there on this.
Nothing wrong per se with DC heater supplies etc.
Hi Nick.
Yes new UL transformers wont be cheap but Ed has PM'd me and offered rewinds of the existing transformers so that should cut the cost down.
I also know that DC heaters in the early stages can be beneficial for hum reduction but to have a separate DC feed to the KT88 heaters then dropped to 4.5v via the big gold resistor mounted on the rear of the chassis is ludicrous! I wonder if matey boy doesn't understand the heating effect of an RMS 6.3v. vs 6.3vdc.
The mods blew two output valves within minutes of each other, caused a valve base to track over and also blew the mains transformer.
Out of interest what's the value of that resistor and which heaters does it feed?
" a DC feed for the output valves" is that the heaters?
Lawrence.
