... And hope you don't overload your heater winding thinking you have 300mA tubes. All heaters are fed voltage. Current regulation floats the voltage. ... But if the temperature of the heater is stable, what does it matter how it gets there if it's normal? If the true specs for a heater are misrepresented just to sell the tube to someone looking for options, then that is bad and is more evidence of the SOP of dubious and dark country sources of product.
Last edited:
Some valve heaters are designed for current.20to20 said:
Not sure what you mean by this. Perhaps you are trying to say that setting the current means you then get whatever voltage the valve settles to? If so, that is true but you can swap 'voltage' and 'current' in that sentence and it is still true.
The basic problem is that modern valve makers don't really know what they are doing. The funniest sign of this is the JJ ECC99 - which has a noval (B9A) base, yet the '9x' number should mean a B7G base. I can only assume that some ignorant person thought that 99 sounded superior to 88.
A 6N23P is supposed to have 310mA heater current (+- 25mA), which puts it in the same bracket as E88CC/6922.
I am working on my 5vp heater circuit. I've built the schematic printed in Allen's Tube Preamp Cookbook more than a few years ago. But recently got to checking it out and the age of the tubes. I've have put a scope on the heaters and see +/- 50mv of ripple. I was surprised it seems like a lot, but its right at the top of the LM340 spec sheet. So I am wondering are there any simple ways to reduce the riople maybe 1/10x?
The voltages on the tubes has raised quite a bit to 8.2v +/- .4v Has anyone developed a servo heater circuit?
The voltages on the tubes has raised quite a bit to 8.2v +/- .4v Has anyone developed a servo heater circuit?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.