[Amps] Should a blower run after amp shutdown?

[Roger (sub1)]

On 6/2/2011 6:20 PM, David Kirkby wrote:
> On 2 June 2011 22:11, Jim  Garland<4cx250b at muohio.edu>  wrote:
>> Like many homebrewers, I've always built a timer into my amps that powers
>> the blower for a couple of minutes after killing power to the amplifier.
>> Today, however, in a conversation with another builder, I began to question
>> whether this is actually a useful feature. (Obviously, exhausting hot air
>> from the enclosure after powering off an amplifier does no harm, but the
>> issue is whether any presumed benefit is worth the effort building in this
>> feature.) Here's my reasoning.

My amp, which is an Emtron DX-2sp which uses an external anode tube 
(Chinese equivalent to a 4CX1500B) ramps up the filament and HV using a 
Triac. On shutdown the instructions are to let the tube idle in standby 
for a couple of minutes before shutting off the filament and fan.  With 
larger tubes like the 3CX and 4CX 3000's, 4000's and 5000's   I think 
I'd like to let them cool for a bit with the filament off before 
shutting off the fan.

73

Roger (K8RI)