[Amps] 3-500 / 4-400 cooling.

[Chris Pedder]

At 14:40 09/10/2005, R.Measures wrote:

>3-500Z air system sockets and chimneys do not provide adequate cooling
>unless a high pressure centrifugal blower is used.

Perhaps that's because air system sockets were designed to be used 
with centrifugal
blowers?

>Such blowers are
>quite noisy and I know of no Ham type amplifier that uses such.   In my
>experiences, the transverse-air, >150mm slow-speed fan cooling system
>used on the Heath SB-220 and Kenwood TL-922 result in lower
>glass-envelope and filament-pin temperatures than those temperatures in
>similar amplifiers that use air system sockets


But the fact remains that both the SB220 and TL-922 suffer failures 
due to inadequate cooling of the filament pins.


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

Perhaps the moral of this story is 'do what the manufacturer suggests'?

Chris G3VBL