Anyone build with a Mercury Magnetics P45RS

[Reeltarded]

You made Martin guess at a thing. You are legend!



Glad to see you on the right path and I would love to hear the outcome when it is done.

[studiodunn]

You made Martin guess at a thing. You are legend!



Glad to see you on the right path and I would love to hear the outcome when it is done.

Lol! I still feel like Martins guess is a pretty solid truth.

I’ll start a build thread soon as I feel like my threads can always help others not make my same mistakes

[studiodunn]

Ok, next fix is the bias voltage. There isn’t a 50v tap on this PT. Can I use the 100v primary lead to feed the bias?

Or is using a 12v transformer and taping the Heater winding a better practice?

[gktamps]

You mean line voltage on the primary?
No, you tap off the B+ of the secondary and use suitable dropping resistors, diodes, etc.
Check out:
http://www.valvewizard.co.uk/bias.html
about midway down the page.

[Phil_S]

I'd add that you'll see Marshall often tapped the B+ for bias voltage. Look at schematics for examples of how they did it. Here's a typical example.

[studiodunn]

Thanks Phil. the board I am building has a pad for a 50v bias feed, so I just need to get the HV dropped and run in at around 50v. the board will handle reversing the voltage for me.

[studiodunn]

Just got this emailed from MM -

P45RS (current).pdf

[martin manning]

Pretty much confirms what you determined above. On the bias supply, I see you are using a PCB. If the bias supply is somewhere on that, or on another board, you'll have to determine what that looks like and adapt it to using the high voltage secondary as the AC source.

[studiodunn]

Pretty much confirms what you determined above. On the bias supply, I see you are using a PCB. If the bias supply is somewhere on that, or on another board, you'll have to determine what that looks like and adapt it to using the high voltage secondary as the AC source.

YEp and I'm glad I didn't get the diagram the first time I asked. i needed to lean how to identify on my own.....or at least via solid advice and expertise.