Tweed champ build blowing power tubes

[JoshBernstein]

I havent put in a new tube yet, ive got a few ordered... ill report back after they come in some time this week.

[Stevem]

If you have another amp that uses 6L6GC or 5881 tubes you can try it with one of those in it and harm will come to the amp!

[stretch2011]

If the ot is shorted then you might not have a load hooked up to it tho causing the tubes to blow.

Measure your primary and your secondary. The secondary should read around .7 to .8ohms for an 8 ohm load. From my experiences bad ot' s have read 12ohms+ on the secondary.

If you know what your primary and secondary is supposed to be you can use the actual impedances and the ratio between them to see how close you are to the primary and secondary.
For instance spitballing here.
Supposed to have a 8k primary and a 8ohm secondary. The ratio is 1000-1. If your secondary reads .7ohms then the primary should read 700ohms.
If my math is wrong someone please correct me.

[JoshBernstein]

Well, my secondary is reading at .7 ohms, and the primary is reading at 337 ohms. The ot only has 1 secondary tap that is supposed to be 4 ohms.

[martin manning]

If you know what your primary and secondary is supposed to be you can use the actual impedances and the ratio between them to see how close you are to the primary and secondary.
For instance spitballing here.
Supposed to have a 8k primary and a 8ohm secondary. The ratio is 1000-1. If your secondary reads .7ohms then the primary should read 700ohms.
If my math is wrong someone please correct me.

DC resistance affects the impedance ratio, but it is only a small part of it.

To get an approximate measurement of impedance ratio you would measure AC voltage on both sides with an AC voltage (a few volts say) applied to the primary. The square of the voltage ratio is the impedance ratio.

[stretch2011]

There we go! I had a gut feeling I had that wrong. Yes just hook up your filament supply to your secondary and measure the voltage across the primary.

[JoshBernstein]

Got new tubes in the mail today. Plugged one in and it didnt blow, but i got some hotrible squealing. Turned out i had the ot primaries backwards.
Anyway the amp sounds great, and isnt blowing tubes so i must have just had a bad one. Thanks for the help everyone!

[Stevem]

Yup, that's the case 95% of the time it's just the tube!