building d-lite but no 50v bias on PT...

[daz]

Hi all,
I've almost finished a d'lite down under (Australia ). i received some custom made d'lite trannies direct from heyboer 9to fit my chassis). however the Pt has no 50v bias tap wire.
Moss kindly suggested taping bias supply from the HW using the diagram attached as a guide.
It was mentioned to re-configure or make a new rectifier board, you will need the 2-3w 220K dropping resistor (in place of the 470R)
following the schematic would dictate that you change the 100uf cap to a pair of paralell connected 47uF/100v balanced with a 15K 2-3w resistor.

What are your guys thoughts on values to get -50v??
Once i get over this hurdle I should be able to get the amp up and running.
I'm not so familar with this stuff. thanks in advance.

[Buschman]

I used a 220k on the HW to feed the bias supply. If you are using the the kits bias board you will have to find a way to mount it. It seem that I had to tweak on the resistor on the bias pot to get the bias voltage in the correct range. It will depend on if you are running 6v6 or 6l6. I will probably mod mine with a bigger pot so I don't have to change resistors to change between 6v6 & 6l6.

[Bob-I]

I'd replace the 470R with a 220K at least 2 watt and measure. You might need to adjust the values of the 200K and the tail resistor a bit, but you won't need a complete redesign like the schem you posted.

Also, dont' treat that -50 as gospel. More important is the idle current through the output tubes. -50 is a good starting point only. Adjust to get about 70% max dissiption.

[daz]

I used a 220k on the HW to feed the bias supply. If you are using the the kits bias board you will have to find a way to mount it. It seem that I had to tweak on the resistor on the bias pot to get the bias voltage in the correct range. It will depend on if you are running 6v6 or 6l6. I will probably mod mine with a bigger pot so I don't have to change resistors to change between 6v6 & 6l6.

thanks for the replies guys!
So Buschman, what resistor values on the bias pot were you using for 6l6 and 6v6? I plan to use 6L6?
cheers

[Buschman]

Right now I have a 56k tail on the bias pot. My PT is running close to 350v on the primaries before rectification & load. This put me on the upper limit for 6l6s -40mf & comfy for 6v6s. It will take some tweaking but it will work fine. Rough it in at -40 to -50v & go from there. The idea is to go down on resistance not up but my supply of 2watt 150k to 250k resistors was limited so I went up on the tail. Sometimes you gotta run what you brung!

[Buschman]

Daz I have a correction for you. I am using a 180k 2 watt. I started with the 220k but had to tweak.

[daz]

thanks I'll see how i go.
Cheers
daz