Unused bias tap on power transformer

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
altarfx
Posts: 3
Joined: Sun Jul 14, 2013 1:45 am

Unused bias tap on power transformer

Post by altarfx »

H
Will the ClassicTone 40-18066 be cool for a 5e3?
datasheet=> http://www.classictone.net/40-18066.pdf

I am interested in this transformer because its an upright mount. I am building a head with a recycled chassis and dont have a way to make a rectangle cut out.

The Voltages all look to be in range, it does have an added bias tap though, if i am not using this would i just not connect and cover the red/blue lead?

thanks a million for any info.
User avatar
martin manning
Posts: 14308
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: Unused bias tap on power transformer

Post by martin manning »

No problem with the unused bias tap. Cut the bare wire off, bend the end over a half inch, and put a piece of heat-shrink tubing over it. You have more rectifier filament current than you need (3A instead of 2), so the voltage might be a little high.
altarfx
Posts: 3
Joined: Sun Jul 14, 2013 1:45 am

Re: Unused bias tap on power transformer

Post by altarfx »

As for the rectifier filament current, is this a safe practice? or might i need to modify the circuit to accommodate the higher voltage?

Thanks for your time!! This is the first time i have had to look for a transformer that was not a direct replacement.
User avatar
martin manning
Posts: 14308
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: Unused bias tap on power transformer

Post by martin manning »

Filament voltage within 10% of spec is ok, so you may not have any real problem. You could ask MC what voltage you can expect at 2A.
tubeswell
Posts: 2337
Joined: Thu Mar 27, 2008 6:42 am
Location: Wellington. NZ

Re: Unused bias tap on power transformer

Post by tubeswell »

altarfx wrote:... it does have an added bias tap though, if i am not using this would i just not connect and cover the red/blue lead?
totally fine
He who dies with the most tubes... wins
altarfx
Posts: 3
Joined: Sun Jul 14, 2013 1:45 am

Re: Unused bias tap on power transformer

Post by altarfx »

cool, thanks guys!!!
Post Reply