Transformer troubles

[sameal]

Hi folks.

I currently intend to build an la2a and a federal am864.

Yeah i know, i got a lot of work ahead of me.

However im trying to hunt down power transformers and i have:

Triad R-6A @480v 50ma, 6.3v 2a, 5v 2a

Stancor P-5058 550v c.t. @ 50ma
6.3v c.t. @2.5 5v@ 2

Hp/paeco 9100-0036 630v
6.3v 3.55a
5v 2a

Unfortunately i think none of these transformers is really what im after spec wise. Im either way over or under. I feel id be shoe horning these into the schem rather then dropping them in

Anybody have any ideas or the correct transformers im after?

 

[CJ]

Triad is perfect, and they make good power transformers,

480/2 = 240  (should have a CT)

 

[sameal]

The triad does have a ct.

But the la2a schem calls out for a 500v p.t.

Wouldnt 480 be a hair light?

 

[CJ]

not at all,

first off, all tube work involves a 20 percent tolerance right off the bat,

add to that carbon comps with a 10 percent tolerance that drifts to 20 percent with age,

add to that a line voltage that has gone from 110 to 120 and you may be too heavy,

plus, you can drop R28 - 47 K 2 Watt to get your 275 B+.

and that Triad has sex appeal when used on a 60's box,

make sure the decal faces outward, 

 

[beatnik]

you won't need a 5v tap for the la2a unless you intend to mod for tube rectification

 

[sameal]

I might go with the triad then.

Im doing a scratch build, so i dont have any decals. But, i might grab some.

All the caps/resistors and stuff are going to be new and modern.

Any of the others look good for the federal? Or am i back on the hunt?

 

[Matt C]

Edcor makes a PT for the AM-864

 

[sameal]

I might end up at edcor, but i got a pile of salvaged iron here im hoping to put into use again. Both of these builds im trying to salvage as much as i can.

I got a few more unidentified p.t.'s, i/o's and chokes n'things to go through.

 

[mjrippe]

I think CJ meant the decal on the Triad 

What are the ratings for the AM/864 power xfmr, might have something around here...?

 

[sameal]

I think CJ meant the decal on the Triad 

What are the ratings for the AM/864 power xfmr, might have something around here...?

According to the schem, 175v a side. So 350?
http://www.waltzingbear.com/Schematics/Misc/AM-864.htm

I have a 350-350 transformer here, but no print as to the taps and no make. I do have a model number

 

[moamps]

  I currently intend to build an la2a and a federal am864.
However im trying to hunt down power transformers and i have:
Triad R-6A @480v 50ma, 6.3v 2a, 5v 2a
Stancor P-5058 550v c.t. @ 50ma
6.3v c.t. @2.5 5v@ 2
Hp/paeco 9100-0036 630v
6.3v 3.55a
5v 2a

You can use Triad for AM864. You need to insert an additional high power (5 or 10W) resistor between second and third section of 47uf capacitors, and adjust it to set HV  to +200V.
Also you can use Stancor for La2a, by inserting an additional  RC network in HV power supply.

By using this mods you will get just better filtered high voltage.

Paeco can be used also by using the same principle (adjusting values of serial resistors), but you will need to care for increased heat and dissipation.

 

[sameal]

You can use Triad for AM864. You need to insert an additional high power (5 or 10W) resistor between second and third section of 47uf capacitors, and adjust it to set HV  to +200V.
Also you can use Stancor for La2a, by inserting an additional  RC network in HV power supply.

By using this mods you will get just better filtered high voltage.

Paeco can be used also by using the same principle (adjusting values of serial resistors), but you will need to care for increased heat and dissipation.

I like that idea. But i dunno if im proficient enough to alter schematics yet. I think i can copy from them, but redesign is a step or two from where im at now.

And now im concerned about the triad having corroded leads and giving me funny readings on the 480v line.