Current Draw and the Dreamtone Calculator

[lord preset]

Well the ratings are confusing, at least to me.

The AS-1T230 is sold as 100VA 230V and specs show two 230v taps @ .22A, and two 6.3v taps @ 3A. The test data on the HT taps indicates that running them in parallel gives 224v @ .38A. It's not clear to me what current you get when running the taps in series to get a center tap.


Then there is the AS-2T230 sold as 200VA 230V with one 230v tap at .40A and one 6.3v tap @ 4 amps. Unfortunately Antek does not offer test data on this one. The AS-2T230 is substantially bigger and heavier than the AS-IT230, so it makes me wonder what the real difference in current is between the two.

[rock_mumbles]

Here's what doesn't make sense:
230V x 0.22A = 50.6VA
230V x 0.22A = 50.6VA
6.3V x 3A = 18.9VA
6.3V X 3A = 18.9VA
Add all of this up and you get 139VA ...

They claim the PT is a 100VA PT so something is wrong with their ratings,
After using them I believe they are slightly overrated ...

From my experience most standard EI transformers with the same voltage ratings will have higher voltage in an amp circuit.

If you hook up an AS-1T230 Antek PT with the HV taps in series for a center tapped PT you will have a 230V-0V-230V (460V) PT @ ~0.20A
I don't think you can load the PT with 200mA and get 460V AC out of it ... with just over 100mA it does supply ~460V

The AS-2T230 is rated at 230V @ 0.40A basically twice the AS-1T230

[rock_mumbles]

Here's a graph of voltage vs. amp current draw for the Antek AN-1T300
[img600]http://i615.photobucket.com/albums/tt23 ... s_load.jpg[/img]

Notice that with a circuit load of about 100mA with a pair of 6V6's it puts out a rectified DC voltage of ~390V which is equal to 1.3 times the 300V AC voltage rating ... this is what you would expect!

But notice that when loaded with about 175mA the rectified voltage is ~365V ... or only about 1.2 times the 300V AC voltage rating a much lower voltage than you would expect ... so this tells me that this isn't really a 300V 200mA PT ...

Compared to other transformers this would be like a 280V-0V-280V 175mA transformer

[matt h]

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[rock_mumbles]

My brother did the graph, the 100mA etc. is the 'measured' current through the pi filter resistor in the amp with 6V6's and 6L6's using different values of cathode resistors.

The PT was wired as a center tapped PT with the two HV in phase and in series ...

[Phil_S]

If you hook up an AS-1T230 Antek PT with the HV taps in series for a center tapped PT you will have a 230V-0V-230V (460V) PT @ ~0.20mA

Maybe Mumbles, you mean 200mA or .2A? I'm going to assume this is the case. Please let it be so or what follows is a total embarrassment!

I am thinking 100VA applies to the primary coil. You then split this up on the secondary side. I'd expect with 6.3V @ 6A = 38W (or 38VA), this leaves 62VA or 62W for the HT windings. If you put them in series for 230-0-230, you get ~62W/460V = ~135mA. (This is consistent with Mumbles result of 139mA.) All this is AC volts.

460VAC solid state rectified will produce about 460*.7*.96 = ~310VDC. 460VAC/310VDC = 1.48; 1.48 * 135mA = 200mA.

Mumbles reports empirical results of 200mA. I don't think that result I got is an accident. Also, i don't think Antek is intentionally misleading anyone.

Hey, I don't really know that much. I won't feel hurt if someone says my analysis here is just a happy accident. If that's the case I'd sure like to see the right way to figure this. I am thinking there has to be a correct mathematical explanation. Really, I'm simply seeking the truth here. Curious minds want to know.

[matt h]

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[Phil_S]

rock_mumbles makes a clear statement about the 1T230, a 100VA PT and that is the one I did the calc for. I actually made this calc a day or two ago and felt assured when I saw that statement and decided to "show my work."

I ignored the graph. I'm not sure which PT that's for!

After all, we get to pick and choose those things on which we comment!

[lord preset]

Note that the Antek AN-1T300 that was the subject of the graph is, like the AS-1T230 is rated at 100VA not 200VA.

And Phil. nice tie.

[matt h]

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[Phil_S]

And Phil. nice tie.

Phil's not wearing a tie. That's his hand!

[Phil_S]

Posted: Wed Oct 08, 2014 9:32 pm, italics/bold added for emphasis and edited for brevity:

Here's what doesn't make sense:
230V x 0.22A = 50.6VA
230V x 0.22A = 50.6VA
6.3V x 3A = 18.9VA
6.3V X 3A = 18.9VA
Add all of this up and you get 139VA ...

LOL, I typed a big long post only to realize, I've misused the 139VA thinking it is the same as 135mA. So, I've deleted that content and if anyone saw it, I'm going to deny it's existence!

I am, however, going to agree this doesn't add up. The math for the filament windings adds up. So the rest is left for the HT windings, which is 62.2VA between the two of them or 31.1VA for each. That makes 100VA. The 50.6VA has got to be an error. I still think we've got ~200mA total for the rectified HT at around 310VDC.

See page 1 (10/8/14 at 11:27am) of this thread for rock_mumbles statement about 310V actual.

[matt h]

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[Phil_S]

460VAC@135mA = 310VDC@200mA. It's just a*b=c.

[matt h]

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