[Amps] Henry amp problem

[R.Measures]

On Oct 17, 2005, at 5:35 PM, Tim wrote:

> Hello all:
>
> I recently acquired a beautiful Henry 2KD Classic desktop amplifier.  
> It works fine and makes good power- but...  It is drawing idling 
> current while sitting in standby.  Henry told me that I probably have 
> a shorted tube but I haven't been able to confirm that fact.  I did an 
> ohmmeter check and the tubes seem fine at DC.

Damaged 3-500Zs often only filament-grid short when the filament is hot 
-- i. e., expanded.  The only way to find such a problem is with a 
high-potential tester.  If the grid-fil breakdown potential is under 
5000v when the tube is cold, it may short when the fil is hot.

>  They are late Amperex 3-500Zs with the plates that look like stacked 
> coins

the graphite plate/anode

> as opposed to the Eimac zigzag folded plate.


>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org