pt for a deluxe

[mark enger]

i have a power transformer from a old magnavox amp, im not sure but i think it ran 2 6v6 in pp, after testing it im only getting about 296 hv. most deluxe trany i see are more like 325 is this pt gonna do it for me. ive built the board and bent a chassis im just a little leary of the prt what do ya think? mark

[tubeswell]

How about running it with a 5R4 or a GZ34, or use SS rectification and run some JJ6V6s at about 410-420?

[Wakculloch]

296V is a perfectly adequate HT level for 2 6v6's, and will allow you to bias them warmly without fear of meltdown.

[tubeswell]

I agree with Wakculloch BTW. (I just thought Mark wanted more B+)

[mark enger]

its just that most deluxe pt i see run at like 330, but this is a free transformer and i want to use it, im using the ceriatone layout the bias resistor on that layout is a 270 ohm does that sound like a good start. i have some very nice 5ar4 0ld stock tubes i could use but id rather set it up using 5u4 or 5y3 as im trying to hold on to the 5ar4 for my 18 watt marshall builds where they sound great, im doing a few of these amp as some friends want them but i aint given up my 5ar4s, so with a 296 hv throu a 5u4 what kind of b+ can i expect and given that voltage what bias resistor should i start with is the 270 a safe bet thanks for your replys mark

[tubeswell]

Well in roundabout terms, a Full Wave SS diode rectifier gets a B+ under load that is about 1.41 x the VAC from the outside of one end of the HT winding to the CT (in your case 296 x 1.4142). A 5AR4 is about 1.3 x, a 5U4G is about 1.2 x, a 5Y3GT is about 1.1 x and a 5R4 is somewhere between a 5Y3GT and a 5U4G, and a 5V4 is slightly higher than a 5R4. Where does that leave it? (Somebody will no doubt dispute these 'facts')

[mark enger]

thanks tubewell looks like my builds a go maybe ill post some pixs as i go, gotta get out my wood working tools as im doing the combo box as well. boards built, chassis bent, got everything ready after these are done im gonna do some with 6l6s, all iv been doing is el84 amps and am excited for the change thanks mark