Ideally the inductance ratio would be 625 also, since that goes by turns squared too. But practically, the measurements were not likely done at the proper scaled currents. Core permeability changing with excitation level messing with the measurements..
Would it be possible that company like Hammond do not know this ?
Anyhow, that data give about 50 % too low impedances. That is quite big error.
I reported Hammond about this and they already replied with additional questions. Let's see what will be their final answer.
Should the ratio of inductances remain the same as both primary and secondary are wound on the same core, what ever the permeability variation is?
Only if the measuring currents used are in the inverse of the turns ratio. (ie, same core excitation level for each case).
Using the same LC meter obviously won't work.
With a Variac to set turns ratio scaled voltages
(with a V meter and an I meter to measure V/I = Zl = 2 pi f L ) should work.
There could be some discrepancy if the winding resistances aren't also in the N^2 ratio, but a well wound xfmr would normally satisfy that rule. (gives lowest power loss for a given winding window)
Using the same LC meter obviously won't work.
With a Variac to set turns ratio scaled voltages
(with a V meter and an I meter to measure V/I = Zl = 2 pi f L ) should work.
There could be some discrepancy if the winding resistances aren't also in the N^2 ratio, but a well wound xfmr would normally satisfy that rule. (gives lowest power loss for a given winding window)
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The EL84 in triode is not exactly the greatest choice. Altho easy to drive with its high triode mu it needs a high plate voltage.
Max plate dissipation is soon reached.
There are a number of dissimliar triodes & triode pentodes used as vertical deflection in TV that make very good SE amps.
Driver & output in a single bottle. Refer to the attached. I've built SE amps with both 6EA7 & 6LU8 with very good results.
Attachments
the 2.5k - 10k primary to 4 - 32 ohm secondary has nothing to do with the inductance of the windings...
transformers transform voltages by its turns ratio......the impedance ratio of 625 is a turns ratio of 25....
You have to use very good switches with reliable conntact at high and low currents.
And the "inproved circuit" doesn't give 4-8-16Ω but 4-9-16Ω 😀
Mona
Shure, but for an article in a magazine they could have been more honnest about it. From an educatioal point of view it's bad practice.
Mona
I have some single ended output transformers that have 4 separate but identical turns secondary windings.
You can have a 1 Ohm, 4 Ohm, 9 Ohm, or 16 Ohm output tap, depending on how you connect them.
You can have a 1 Ohm, 4 Ohm, 9 Ohm, or 16 Ohm output tap, depending on how you connect them.
