11-10-2018, 02:12 PM
Sorry it's a guarded secret, only us old guys know!!! [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif][Image: http://philcoradio.com/phorum/images/smi...on_lol.gif]
It goes something like this. In your set you have nine tubes. To determine the hv current you need to know how much each tube consumes. Two of the tubes don't consume any hv current and those would be the 84 (it delivers the current) and the 7A6. So those don't count in the HV circuit that leaves the other seven. The mixer, osc, if, and 1st audio are going to be abt 5ma each. The output tube are going to be much higher abt 20ma each. Add it up and you get 65ma. Another thing to look at is the max current that the 84 can deliver spec is 60ma. Hv current calculation can vary as a lot is dependent on how much hv is applied to each tube and the amount - bias on the control grid. This will get you in the ballpark.
High voltage voltage can be figured by taking the dc hv at the cathode of the 84 and multiply X2. You've got 265vdc x2= 530v. I must have rounded down a little. So than = 530v center tapped (265v on each side of center).
Heater current. Most 6v tubes the current is 300ma but there are many exceptions. Rectifiers and output tubes generally are higher. In your set you have five tubes @ 300ma = 1.5A The 84 is 500ma and the 41's are 400ma ea. There are four lamps but only two are at one time so that's 150ma ea (if they are #47 bulbs). so add that up and you get 3.1A. Looks like 100ma got away from me on my previous post.
In the world of power transformers more current capabilities is better but not higher voltage. More current capability means a cooler running transformer.
It goes something like this. In your set you have nine tubes. To determine the hv current you need to know how much each tube consumes. Two of the tubes don't consume any hv current and those would be the 84 (it delivers the current) and the 7A6. So those don't count in the HV circuit that leaves the other seven. The mixer, osc, if, and 1st audio are going to be abt 5ma each. The output tube are going to be much higher abt 20ma each. Add it up and you get 65ma. Another thing to look at is the max current that the 84 can deliver spec is 60ma. Hv current calculation can vary as a lot is dependent on how much hv is applied to each tube and the amount - bias on the control grid. This will get you in the ballpark.
High voltage voltage can be figured by taking the dc hv at the cathode of the 84 and multiply X2. You've got 265vdc x2= 530v. I must have rounded down a little. So than = 530v center tapped (265v on each side of center).
Heater current. Most 6v tubes the current is 300ma but there are many exceptions. Rectifiers and output tubes generally are higher. In your set you have five tubes @ 300ma = 1.5A The 84 is 500ma and the 41's are 400ma ea. There are four lamps but only two are at one time so that's 150ma ea (if they are #47 bulbs). so add that up and you get 3.1A. Looks like 100ma got away from me on my previous post.
In the world of power transformers more current capabilities is better but not higher voltage. More current capability means a cooler running transformer.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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