25Z6 Rectifier to Solid State Conversion?

[Electronic M]

The 25Z6 was usually used in series string heater sets so you can roll your own by downloading the 25Z6 datasheet. Use the heater voltage and current in this equation R=voltage/current to calculate the resistor you need to replace the heater with and multiply the voltage times current to get the wattage that resistor needs to be (it's wise to get a resistor twice that wattage so it doesn't run hot.

Once that's done wire a 1n4007 in place of each diode on the schematic symbol for the tube. You can take the base of a dud tube and install the diodes and resistor in it.
Most commercial replacements are this plus a bunch of bucks to pay someone else to build it.... I'm cheap and usually have all the parts I need to build one so I usually roll my own.

[Jon1967us]

Originally Posted by Electronic M

The 25Z6 was usually used in series string heater sets so you can roll your own by downloading the 25Z6 datasheet. Use the heater voltage and current in this equation R=voltage/current to calculate the resistor you need to replace the heater with and multiply the voltage times current to get the wattage that resistor needs to be (it's wise to get a resistor twice that wattage so it doesn't run hot.

Once that's done wire a 1n4007 in place of each diode on the schematic symbol for the tube. You can take the base of a dud tube and install the diodes and resistor in it.
Most commercial replacements are this plus a bunch of bucks to pay someone else to build it.... I'm cheap and usually have all the parts I need to build one so I usually roll my own.

Looks like at 300mA, the resistor for the filament would be around 83Ω.

Referencing: https://frank.pocnet.net/sheets/127/2/25Z5.pdf

So I have the 83Ω across pins 2, 7
and a 1n4007 across pins 5 (anode), 8 (Cathode/stripe)
and another 1n4007 across 3 (Cathode/stripe) and 2 (anode)

Does this look correct?

[Notimetolooz]

1N4007 across pin 3 and 4 (stripe).

Note that the resistor will need to be at least 10 watt, (15 W would be better) .

Unless you have a lot of power resistors, you might get the tube before you get the resistor(s).

[Jon1967us]

Originally Posted by Notimetolooz

1N4007 across pin 3 and 4 (stripe).

Note that the resistor will need to be at least 10 watt, (15 W would be better) .

Unless you have a lot of power resistors, you might get the tube before you get the resistor(s).

Thats correct. I meant the diode across 3/4

Yes, I used 2 10w resistors for 80ohms.

The SS replacement I made seems to work fine! Getting more or less the right voltages, HV and a raster now.

[JohnCT]

Originally Posted by Jon1967us

Getting more or less the right voltages, HV and a raster now.

If you didn't add a B+ dropping resistor or bucking zeners on the diodes, your voltage is going to be high. That's generally not a problem short term as long as you aren't stressing the electrolytics or your HV isn't too high.

John

[Jon1967us]

Originally Posted by JohnCT

If you didn't add a B+ dropping resistor or bucking zeners on the diodes, your voltage is going to be high. That's generally not a problem short term as long as you aren't stressing the electrolytics or your HV isn't too high.

John

I didn't add a zener or dropping resistors. If anything the LV supplies are 8-14V lower than the numbers I have in my Rider's. May be due to the rectified voltage coming off the Selenium being a little low. I will probably end up dropping a 1n4007 to sub that out too. Will definitely be using a dropping resistor there.