[Amps] Coupling a blower to an air system socket

[Roger (K8RI)]

On 3/15/2013 10:09 PM, Bill Fuqua wrote:
>    I believe the air system socket connected to a duct is especially
> useful when
> you can't have a pressurized cabinet. There are situations where large
> cabinets
> are used and sealing them is not possible.

IIRC Henry used fairly large blowers mounted under the RF deck in the 
power supply section. It's more of combination of under the sockets, but 
still pressurizing that compartment.

The old Collins KWS-1 did something similar, but mounted the blower in 
the PS and coupled it to the final through a flexible hose, much like a 
radiator hose.
>

73

Roger (K8RI)

> 73
> Bill wa4lav
>
> At 09:04 PM 3/15/2013 -0400, KA4INM wrote:
>> On 03/15/13 16:58, Alan Ibbetson wrote:
>>
>>> For minimum airflow resistance for a forced air cooled amplifier it
>>> would seem the blower needs to discharge in a straight line directly
>>> into the underside of the valve socket. This leads to a fairly tall
>>> structure with the blower underneath the RF deck.
>>
>>> What is the "right" way to make the physical connection between blower
>>> and air system socket? Rigid ducting? Something resilient like rubber?
>>> Or (what intrigues me) how about a fabric transition duct as shown in
>>> several places here
>>
>>> http://users.pipeline.com.au/~burst/stc.htm
>>
>>> The "floppy" fabric seems attractive as a way to take up minor (major?)
>>> misalignment between the blower and RF deck if they are built as
>>> separate units and should help isolate any blower vibration. A competent
>>> seamstress (seam-master) would be able to take differences in duct shape
>>> and size in their stride too.
>>
>>> Has anyone got a feel for the pros and cons of the use of fabric rather
>>> than more rigid blower couplings?
>>
>>   I should think the difference is negligible and not worth the bother.
>> Many successful amplifiers using all kinds of air cooled tubes have
>> been built with the system where they are simply pressurizing the box
>> under the tube/s with the air passing through or around the tube/s above.
>> --
>>   Ron  KA4INM - Youvan's corollary:
>>                 Every action results in unwanted side effects.
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