3fp7 2nd anode

[timmy]

Is there a way to make a simple 2k supply for the 2nd anode of a 3fp7 ?

[Electronic M]

I think on ARF there was a topic for those that own either the halicrafters or the Philco electrostatic sets that are notorious for HV supply issues about a module that could make HV. I think it may have had variable output. Might be worth looking at.

[dtvmcdonald]

Simple: yes. Easy: yes. Expensive or lucky: Your Choice. Heavy: usually.

The lucky part: find an old TV, radio, or guitar amp power transformer. These usually
are for 350 to 400 volt B+, full wave (CT). Thus using the whole B+ winding will
get you 700 - 800 volts under heavy load. A voltage tripler will get you the desired 2 kV.


With these transfoprmers, to drive a CRT even quintuplers work fine. But they are
still fatal if used as electric chair supplies.

[timmy]

Originally Posted by dtvmcdonald

Simple: yes. Easy: yes. Expensive or lucky: Your Choice. Heavy: usually.

The lucky part: find an old TV, radio, or guitar amp power transformer. These usually
are for 350 to 400 volt B+, full wave (CT). Thus using the whole B+ winding will
get you 700 - 800 volts under heavy load. A voltage tripler will get you the desired 2 kV.


With these transfoprmers, to drive a CRT even quintuplers work fine. But they are
still fatal if used as electric chair supplies.

So using 350-400v I assume ac not rectified this voltage into a tripler ?

[kf4rca]

Check this out:
https://www.ebay.com/itm/31569351642...8GVBP7SXKATW2V

[timmy]

Originally Posted by kf4rca

Check this out:
https://www.ebay.com/itm/31569351642...8GVBP7SXKATW2V

yes I have one but it says it puts out 15k which is very weak and it may work.

[old_coot88]

Gotta wonder how well triplers and quadruplers designed for horz sweep frequency will work on 60 hz. Seems like the internal capacitors would be too low a value.

[dtvmcdonald]

Originally Posted by timmy

So using 350-400v I assume ac not rectified this voltage into a tripler ?

That's correct ... AC goes into the tripler. As another person mentioned, potted
triplers for horizontal frequency will not work. You need film caps and 2 kV or more diodes.

Oh yes! IF you look hard you can find used HEathkit scopes and modulation monitors that will
have the necessary stuff in them. These may or may not be cheap.

[timmy]

Originally Posted by dtvmcdonald

That's correct ... AC goes into the tripler. As another person mentioned, potted
triplers for horizontal frequency will not work. You need film caps and 2 kV or more diodes.

Oh yes! IF you look hard you can find used HEathkit scopes and modulation monitors that will
have the necessary stuff in them. These may or may not be cheap.

I do have a hv generator that produces 2k and this would probably work well. This is for a 3fp7 tube that I may attempt to fit in a pilot tv it would be better then a green tube. And it just has to have 2k present for the tube to light bright there wouldn’t be any draw. But the hv generator works on 3.7v dc so how to get that voltage from a pilot to run this would be interesting.

[bgadow]

I installed a filament transformer in my Pilot for the CRT. Something like that word work, if the draw isn't too severe. I'm sure there are more clever ways, though.

[Electronic M]

Originally Posted by bgadow

I installed a filament transformer in my Pilot for the CRT. Something like that word work, if the draw isn't too severe. I'm sure there are more clever ways, though.

Yeah, if you have 6.3VAC for heaters just rectify that, filter it, and feed that to an LM317 or LM337 and you can get up to 2A if stable regulated DC voltage. You'll need a resistor divider on the feedback to set voltage but a pot can do the job without the math.