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Spiderleggs
| | Posted on Thursday, April 24, 2003 - 3:43 am: | 
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Can tube filaments run on either ac or dc? I was looking in a friend of mine's phantom which has 6jg6a drivers, and he is going to change them to 12 volts with an outboard filament supply but didn't know if they had to be dc or ac. They seem to be ac as it is but he has a 12 volt dc supply now. Also instead of all being in parallel or series, each 2 seems to be in parallel with each other, as you can unplug one and one other will go off, but the other 2 stay lit and vice-versa.
He is also going to change the finals later, but they seem to be wired differently than the drivers. |
Tech833
| | Posted on Thursday, April 24, 2003 - 10:10 pm: |
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The filaments should not care. HOWEVER, be advised that running the filaments too hot will shorten the life of the tubes by a LOT. Most tube filaments are voltage rated at AC. In many circuits, running the filaments at DC potential (hot to ground) will introduce unwanted coupling between grids. |
Jp1116
| | Posted on Friday, April 25, 2003 - 7:53 am: |
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The tubes are already getting 12 volts so it shouldn't be necessary to run an outboard transformer. If you just wire the filaments in parallel instead of in series you should be okay. I've never changed anything to run 12 volt tubes, it is always changing it to run 6 volt tubes to get rid of the 8950's. What are you going to replace the tubes with? Just curious, I was going to make the changes and use some 6KG6's and see what happens but I thought I would see what you were going to use. |
Spiderleggs
| | Posted on Friday, April 25, 2003 - 10:03 am: |
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Thanks 833. I told him about your message, so he will leave it ac instead of changing it to dc. Jp1116, I got it wrong, he is changing them to 17 volt tubes. He is going to use 17kv6a's. The 6kv6a's can replace the 6jg6a, but both are higher than the 6lq6 finals. The 17kv6a's are around 1/4 of the price of the 6jg6/6kv6. It has 4 6jg6's driving 6 6lq6's. I had never seen that combination before in a phantom, but had seen it in a maverick. I think he will use the 6kg6's to replace the 6lq6's. |
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