Voltages all high on one C4S board [resolved]

[carlsor]

I notice that the high voltage goes to the three tubes at the same time the filaments start heating up.
My other tube projects used tube rectifiers or a time delay-on relay to allow the heaters to warm up before the tubes were slammed with high voltage. Supposedly this delay extends tube life.

Any downside to adding a delay to my Mainline?

 

[Paul Birkeland]

Putting two identical caps in parallel isn't really bypassing.  Bypassing refers to putting a very small capacitor across a much larger one.

A time delay-on relay could potentially be added to the Mainline, but you'd probably also need to add a power transformer to power it.  I haven't yet been able to exhaust a pair of 6C45 tubes, so it's quite difficult to make any real statement about their life expectancy and how that might change with various modifications. 

You can populate the A side of each high current C4S board with a cap and a resistor to more slowly apply B+.  We haven't tested this, and I'm not 100% sure the 10,000uF caps will fit all that well if larger parafeed caps are installed, but it's an inexpensive experiment that doesn't involve drilling holes in the chassis or figuring out if your time delay relay is going to work with a voltage doubler. 

 

[carlsor]

Thanks Paul.

I recommend 12-rocketman in ebay as a source of 6C45P tubes. Price is $10.90ea with reasonable shipping from Russia.
Tubes sounded great too.

carlsor