21-11-2020, 06:25 PM
I've looked at the trader sheets and confirmed your calculations. Dropping 231V to 136V in a 3K9 means it will disspate almost 2.5W. I wonder if that includes powering the transistorised UHF tuner too which may account for the rather high current.
Do you have a bench HT PSU? Incredibly useful for valve experiments. I'm fortunate in having 2 Solartron HT PSUs.
Is your 12V to HT a home-built PSU? I though buck converters could only do step down: https://en.wikipedia.org/wiki/Buck_converter
I don't know if you have a variac, but you can make a simple variable voltage HT supply by using one to control the primary voltage of your HT transformer/rectifier. It won't be regulated but it's a lot better than nothing.
Do you have a bench HT PSU? Incredibly useful for valve experiments. I'm fortunate in having 2 Solartron HT PSUs.
Is your 12V to HT a home-built PSU? I though buck converters could only do step down: https://en.wikipedia.org/wiki/Buck_converter
I don't know if you have a variac, but you can make a simple variable voltage HT supply by using one to control the primary voltage of your HT transformer/rectifier. It won't be regulated but it's a lot better than nothing.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
