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What plate voltage do you use? And regulated G2 voltage? How about the forced cooling?
I’ve used them for RF (incl. 4cx250), so I’m interested in your results.
Regards, Gerrit
I’ve used them for RF (incl. 4cx250), so I’m interested in your results.
Regards, Gerrit
Are you running the 4X150A as a pentode?
Knowing your available plate voltage at the bare minimum would help to recommend a proper loading impedance.
Knowing your available plate voltage at the bare minimum would help to recommend a proper loading impedance.
It is impossible to run a 4X150 as a Pentode.
There is no g3 suppressor grid.
(also, there is no Beam Former metal structure connected to the cathode either)
The 4X150 is a Radial Beam Power Tetrode.
It contains:
Filament
Cathode (circular cathode)
Control Grid (Bird Cage)
Screen Grid (Bird Cage)
Plate (Circular plate)
Special cooling finned heat sink around the plate
What makes it a Radial Beam Power Tetrode:
The two Bird Cage grids have the same number of upright wires.
The two Bird Cage grid rotations are aligned perfectly (so that the cathode and plate can "see" each other through the spaces between the upright wires of the two aligned bird cage grids).
Now you know why I dislike calling a 6L6, KT88, or similar tube, a Beam Tetrode. All those tubes have Beam Formers that are connected to the cathode.
Calling those tubes Beam Tetrodes, makes people think the 4X150 Radial Beam Tetrode as if it is similar to a Beam Power tube. Nothing could be further from the truth.
Please call 6L6, KT88, and similar tubes, Beam Power tubes.
Calling them Beam Tetrodes can confuse many people.
There is no g3 suppressor grid.
(also, there is no Beam Former metal structure connected to the cathode either)
The 4X150 is a Radial Beam Power Tetrode.
It contains:
Filament
Cathode (circular cathode)
Control Grid (Bird Cage)
Screen Grid (Bird Cage)
Plate (Circular plate)
Special cooling finned heat sink around the plate
What makes it a Radial Beam Power Tetrode:
The two Bird Cage grids have the same number of upright wires.
The two Bird Cage grid rotations are aligned perfectly (so that the cathode and plate can "see" each other through the spaces between the upright wires of the two aligned bird cage grids).
Now you know why I dislike calling a 6L6, KT88, or similar tube, a Beam Tetrode. All those tubes have Beam Formers that are connected to the cathode.
Calling those tubes Beam Tetrodes, makes people think the 4X150 Radial Beam Tetrode as if it is similar to a Beam Power tube. Nothing could be further from the truth.
Please call 6L6, KT88, and similar tubes, Beam Power tubes.
Calling them Beam Tetrodes can confuse many people.
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Want to try something different?
Just for fun?
Take on a challenge?
Build a low power tube amplifier.
Start with a 4X150.
Ground the Plate.
Use a B+ of 300V to 400V, connect the Screen to an output transformer primary, to B+.
Set the g1 bias for 12 Watts Screen dissipation. 40mA @ 300V; 30mA @ 400V.
Now use the Screen as if it is a 'Plate' (12W maximum dissipation).
The u, (g1 to g2 u) is 5.9.
I recommend some level of air cooling for the tube, the filament heat and screen heat need to be taken care of.
I built this kind of circuit years ago, but instead I used a 4-65A tube.
Just for fun?
Take on a challenge?
Build a low power tube amplifier.
Start with a 4X150.
Ground the Plate.
Use a B+ of 300V to 400V, connect the Screen to an output transformer primary, to B+.
Set the g1 bias for 12 Watts Screen dissipation. 40mA @ 300V; 30mA @ 400V.
Now use the Screen as if it is a 'Plate' (12W maximum dissipation).
The u, (g1 to g2 u) is 5.9.
I recommend some level of air cooling for the tube, the filament heat and screen heat need to be taken care of.
I built this kind of circuit years ago, but instead I used a 4-65A tube.
Note that control grid dissipation is 2 watts max. My dad warned me to obey that rating or bad things will happen.
I have quite a few 4x150s burning a hole in my junk drawer. I just do not need so much power or else they would be in use for a push-pull woofer (up to 400hz) amplifier.
I have quite a few 4x150s burning a hole in my junk drawer. I just do not need so much power or else they would be in use for a push-pull woofer (up to 400hz) amplifier.
It’s can run nicely with hi voltage at the plate and g2 supply buy fine regulator
Chathode bias and bypas cap. Add some gridstoper and grid leak resistor output transformer calculated from rp ht and iq. It’s can run with fan under chassis normally operation temperature no burns or over heat finally got a 20 watt smooth soft and dynamic sound
Regard
Nsaran
Chathode bias and bypas cap. Add some gridstoper and grid leak resistor output transformer calculated from rp ht and iq. It’s can run with fan under chassis normally operation temperature no burns or over heat finally got a 20 watt smooth soft and dynamic sound
Regard
Nsaran
Anyone have triode curves? I recently measured on resistance connected as a triode. Forgot the number though.
I guess I will take up the job of the push-pull low power build. Shooting for about 60-100 watts. likely ultralinear or triode. My junkbox (crawl space) probably has all I need.