Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on June 16, 2017, 10:22:40 pm

Title: Lowering B+
Post by: TIMBO on June 16, 2017, 10:22:40 pm

Hi guys, I have this now sorted. http://el34world.com/Forum/index.php?topic=22066.0 (http://el34world.com/Forum/index.php?topic=22066.0)
The PT has a HT of 360-0-360, so I was taking it as gospel, but in fact it's producing 380v each leg.
This inturn gives me 450v after the 5u4gb rect loaded. So all good

The one concern is when on standby the dual 32/32-500v cap sees 520v

Do adding zener diodes on the PT CT cause a problems to a rectifier valve
 

Title: Re: Lowering B+
Post by: kagliostro on June 17, 2017, 02:35:10 am

Ciao TIMBO

If you have a bias tap (that you use) on that transformer, if you add zener on the CT, remember that bias components values must be revised in order to maintain the same negative voltage

About zener on CT and problems to the tube rectifier, I think that there aren't, but wait for the opinion of someone who is more skilled than I'm

--

The 380v are without load or with load ?

Franco

Title: Re: Lowering B+
Post by: TIMBO on June 17, 2017, 04:58:00 am

Thanks K, 380v is loaded.