OT impedance

[jestaudio]

in have a couple of telefunken SE trannies, the secondry is near as dammit 4 ohms the primary around 600 ohms yet from the documentation the primary shoud be 1.2k, does this sound as if the traffo is U/S

[Phil_S]

Just how did you determine 600:4 as the impedance ratio?

[diagrammatiks]

are you sure it's not 8ohm at 1.2k?

[jestaudio]

Just how did you determine 600:4 as the impedance ratio?

I was,nt aware i had, i was refering to measurements taken with my DMM in comparison to the information printed on the traffo, the question being if the traffo manufacturer states a impedance of 1.2k and i am reading 600 ohm is the traffo defective

[diagrammatiks]

you can't measure it like that.

it's just a ratio.

8:600, 16:1200, and 4:300 are functionally the same transformer.

[jestaudio]

you can't measure it like that.

it's just a ratio.

8:600, 16:1200, and 4:300 are functionally the same transformer.

not to sure i,m following you, correct me if i,m wrong , 4-300 would give 1.2k, is that correct? if so allowing for my DMM not deing my most acurate and slight corrosion i could well be in the ball park

[diagrammatiks]

sorry you said 4:600 in your original post.

that would be 2:300, 4:600, 8:1200, 16:2400

[jestaudio]

sorry you said 4:600 in your original post.

that would be 2:300, 4:600, 8:1200, 16:2400

Now i am confused how do the readings inter-relate to ratios, sorry if i,m being dense

[diagrammatiks]

you have to determine the reading on the primary and then the secondary.

that sets up a ratio between the two windings.

if your primary reads 600ohms and your secondary reads 4 ohms then that's a 600:4 ratio.

That means if you hook up a 4 ohm speaker to the secondary the primary will see 600 ohms.

If you hook up an 8ohm speaker to the secondary the primary will see 1200ohms.

[Aurora]

You cannot use a DVM and measure the DC resistance to determine impedance ratio. DC resistance of teh windings tells nothing about impedance, or rather turns ratio. DC measurements can only briefly tell if the trafo is not shorted or burnt. If there are som specs printed on the trafo, or if you have a spec sheet, you have to rely on them.

[Phil_S]

Just how did you determine 600:4 as the impedance ratio?

I was,nt aware i had, i was refering to measurements taken with my DMM in comparison to the information printed on the traffo, the question being if the traffo manufacturer states a impedance of 1.2k and i am reading 600 ohm is the traffo defective

Are you measuring Ohms? That's not how it's done!
You've got to determine the turns ratio based on voltage in/voltage out. Read here: http://www.radioremembered.org/outimp.htm
Use the voltage supplied by a filament winding as your low voltage source.

[jestaudio]

you have to determine the reading on the primary and then the secondary.

that sets up a ratio between the two windings.

if your primary reads 600ohms and your secondary reads 4 ohms then that's a 600:4 ratio.

That means if you hook up a 4 ohm speaker to the secondary the primary will see 600 ohms.

If you hook up an 8ohm speaker to the secondary the primary will see 1200ohms.

ok so each time i step up a speaker impedance then the primary impedance goes up as well,
yep i think i have it now, just need to find out if i can use this in a 6v6 champ build im looking at

[diagrammatiks]

You cannot use a DVM and measure the DC resistance to determine impedance ratio. DC resistance of teh windings tells nothing about impedance, or rather turns ratio. DC measurements can only briefly tell if the trafo is not shorted or burnt. If there are som specs printed on the trafo, or if you have a spec sheet, you have to rely on them.

yes yes. sorry if that wasn't clear.

make sure you use the right measurements to determine the ratios.

[jestaudio]

You cannot use a DVM and measure the DC resistance to determine impedance ratio. DC resistance of teh windings tells nothing about impedance, or rather turns ratio. DC measurements can only briefly tell if the trafo is not shorted or burnt. If there are som specs printed on the trafo, or if you have a spec sheet, you have to rely on them.

yes yes. sorry if that wasn't clear.

make sure you use the right measurements to determine the ratios.

just rechecked using my works DVM and got 360-4 which would give me about 1400 which is,nt far off the stated 1.2k on the trafo so i would assume if i load it with 8 or 16 ohm speakers that would give me 2.4 or 4.8

[Aurora]

You still refrain from getiing the point?