04-22-2021, 02:02 PM
OK.
Let's assume we want to see 7,000 ohm of impedance as it is a 42 tube. Your original VC is 1 Ohm.
The ratio therefore is 7000 and the square root of that is 84, which is your required turn ratio for the transformer that is there right now.
You could check it by feeding 84V from a Variac to the Primary and measuring the output that should be around 1V.
Now you want it for 3.2 Ohm. The turn ration required for your now needed transformer is then 47.
In the same fashion, take any of your transformers and start feeding say 50V into the primary and measuring the secondary; then record it all.
Calculate the ratios. Pick the one closest to 47. If the difference is too large, you will have to find another one. This is where the Hammonds 125-SE series is suitable.
Let's assume we want to see 7,000 ohm of impedance as it is a 42 tube. Your original VC is 1 Ohm.
The ratio therefore is 7000 and the square root of that is 84, which is your required turn ratio for the transformer that is there right now.
You could check it by feeding 84V from a Variac to the Primary and measuring the output that should be around 1V.
Now you want it for 3.2 Ohm. The turn ration required for your now needed transformer is then 47.
In the same fashion, take any of your transformers and start feeding say 50V into the primary and measuring the secondary; then record it all.
Calculate the ratios. Pick the one closest to 47. If the difference is too large, you will have to find another one. This is where the Hammonds 125-SE series is suitable.
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