Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: mdub71 on February 03, 2015, 09:00:45 AM

Title: variac?
Post by: mdub71 on February 03, 2015, 09:00:45 AM

I'm still assembling this kit, and I'm a ways away from the resistance tests and then actually applying voltage, but I have a question about the first time voltage is applied. Is it a good idea to use a variac for the first time voltage is applied? I'm wondering if the soft start components might not appreciate the variac? Thanks in advance. matt

Title: Re: variac?
Post by: Grainger49 on February 03, 2015, 10:52:57 AM

A variac is more often used starting up older equipment that might have shorted power supply caps.

I'm not aware of anyone else who has started up Paramounts with a variac.  The soft start does its job very well.

Title: Re: variac?
Post by: Paul Birkeland on February 03, 2015, 01:41:19 PM

You can use a variac if you want to, but you won't get any useful voltage readings until you are at line voltages.

The soft start circuit provides a 2A3 grid bias during startup before the driver tube draws enough current to draw that voltage down appropriately on its own. 

-PB

Title: Re: variac?
Post by: mdub71 on February 04, 2015, 06:50:34 AM

thanks for the replies.
mw