Help ID a Mains transformer for 135W Twin

[FFM]

HI All,

I have a 135W UL Twin Reverb and I would like to find out if the Mains Transformer can handle 4 x KT66. Here are the numbers on the Transformer

PT-2-013830
E1A 606-742

Anybody know what the heater specs are? 6.3V, 7A or 5A?

Thanks,

FFM

[Enzo]

Plug your tubes into the amp and turn it on. Has the 6v winding sagged or is it holding up? if it can keep up 6.3VAC with the load, then it is OK.

[FFM]

Grazie ENzo.

I guess I can also run the amp without the v1 and v5 tubes to recover another 0.6 A as I use neither the normal channel nor the vibrato

[MWJB]

"I guess I can also run the amp without the v1 and v5 tubes to recover another 0.6 A as I use neither the normal channel nor the vibrato" Indeed you can. Be sure to check plate current.

[FFM]

yep, will do.

i am in Germany and we have around 230v coming out of the walls. with the 240voltage selector on the amp, i am getting around 475volts on the plates and around 5.9volts on the heaters. with the 220 voltage selected on the amp, around 515volts slamming the plates and around 6.5v on the heaters.

[MWJB]

5.9VAC is too low for the heaters, the higher voltages (220VAC tap) sound more typical for a UL Fender amp.

[Enzo]

Well, the voltage you start with matters, but the test is all about how much voltage sags. If the larger tubes don;t drag the voltage down excessively - whatever it started out as - then the load is not excessive for the transformer.

[bluesfreak]

013830 is speced for 7A normally so your trannie should sustain. If not Welter has a 7A replacment for the 013830 => N 11 F1.
However, I hope you will like the sound of the KT66 as the OT is somehow off the perfect impedance as 4x KT66 like to see 3.5-4K Raa while the 7ender 135W UL OT has only 2.5k Raa....

[FFM]

013830 is speced for 7A normally so your trannie should sustain. If not Welter has a 7A replacment for the 013830 => N 11 F1.
However, I hope you will like the sound of the KT66 as the OT is somehow off the perfect impedance as 4x KT66 like to see 3.5-4K Raa while the 7ender 135W UL OT has only 2.5k Raa....

thanks1, i also wonder if kt66 will fit as the tube sockets are right next to the power transformer.

where in germany are you? maybe you could help me with a schematic or drawing to install a bias adjustment potentiometer?

[bluesfreak]

KT66 specs a min distance of 8cm socket center to socked center so it could be a close encounter for that tube. I am located in south east germany, between Nuremberg and Regensburg, shoot me a mail if u need mor info...

[MWJB]

Tube data sheets tend to space tubes farther apart than amp manufacturers actually end up doing. As far as practical spacing goes I have run 6550, KT88 & KT66 in many tolex 6L6 Fender chassis without problems. You might run into problems installing them into smaller tweed chassis/those designed for 6V6.

If in doubt compare the width of your 6L6s, and subsequent PT clearance, against the bottle size quoted for the KT66 you intend to use.