power transformer

[ernie_jr]

I have a P/T that is 800 ct 200ma, 5v 3 amp and 6.3 volt 6 amp.
Can I run  4 x 6l6's with it, or do I need more current on the 800 volt tap?
Thanks,
Ernie

[DummyLoad]

I have a P/T that is 800 ct 200ma, 5v 3 amp and 6.3 volt 6 amp.
Can I run  4 x 6l6's with it, or do I need more current on the 800 volt tap?
Thanks,
Ernie

i wouldn't build 4 x 6L6GC around it. 450-500mA is where you'd like to be with 4 x 6L6GC.

use it with a pair of KT88/6550?

that thing is going to smack round a lot of B+ unless you load heck out of it.

i used a similar chunk of iron to lite up the glo-champ - IIRC it made around 540V w/ FW SSR and ~135mA load.

peace.

--DL

[ernie_jr]

I have used the same transformers to build 2 amps that are 2 x 6550's. I have one left over and I was looking
for something different to build.
Ernie

[PRR]

Solid or hollow rectifier?

At ~~550V DC, 200mA max, use something like the last condition on page 2 of the 7027A datasheet:

http://www.mif.pg.gda.pl/homepages/frank/sheets/049/7/7027A.pdf

Tube is tube. Any tube which will stand the strain will come close to these values.

This condition gives max current of 220+21.4= 241.4mA. Your PT may survive this for many-many power-chords (since when not maxed-up the current is 105mA).

To adjust closer to 200mA, increase the load impedance by factor 241.4/200. 7,846 ohms CT; round to 8K. Power output reduces by the same factor... around 63 Watts.

It is hard to find high power OTs in high impedances.

> 4 x 6L6's

6L6GC and 7027 are the same TV tube in different bottles and pinouts. While 560V is above the published max plate voltage of 6L6GC, that was probably mis-marketing, and we know all modern production 6L6GC will survive 560V for useful lifetimes.

Therefore you only need two 6L6GC.

Note also that 7027 data shows just 400V on G2. With your lower current you only need ~~350V on G2. Because G2 current may vary from 4mA idle to 18mA loud, you can't simply drop it with a resistor. Leaving G2 way-high will need huge G1 bias to control idle current.

> 4 x 6L6's

Sure, any job which can be done in two 6L6GC can be done with four 6L6GC. Each tube works half as hard. Now you really want to lower G2 voltage, more like 225V, because with high G2 you need way-huge G1 bias to keep down to reasonable idle current, and if/WHEN something goes wrong (bad or shorted load), four 6L6 with excessively high G2 voltage will dump BIG current and something will smoke.  

[ernie_jr]

Thanks PRR,
Looks like another 2 x 6500 (kt88) build. I have about 7 sets of tubes and a blank chassis waiting for work.
Ernie