Hi Ian,
Yes, it would be imprudent to operate the amplifier without its cover
installed, just as it would be to operate a pressurized chassis (blower, air
system socket, chimneys) without its bottom cover installed!
WB2WIK/6
"If everything seems under control, you're just not going fast enough." -
Mario Andretti
> -----Original Message-----
> From: Ian White, G3SEK [SMTP:G3SEK@ifwtech.co.uk]
> Sent: Tuesday, December 03, 2002 4:04 PM
> To: amps@contesting.com
> Subject: Re: [Amps] Q: Chimneys for 3-500/4-400??
>
> Steve Katz wrote:
>
> >I'm guessing:
> [...]
> >
> >-The critical and well-selected spacing of the axial fan to the tube
> >envelopes results in about equal cooling of the entire envelopes,
> >including the surface opposite the side with the air applied -- kind of
> >clever.
> >
>
> A while ago, I made some rough measurements on the 3-500Z in an SB-1000,
> using thermal-sensitive labels on the glass. That amp has a 6in
> Muffin-type fan blowing across the tube, with the air outlet for the
> whole cabinet on the opposite side of the tube.
>
> In normal operation the temperature on the downstream side of the tube
> was a little higher than the upstream side... maybe 50C, not enough to
> be a problem.
>
> The real problem came when the top cover was removed. When there was no
> outlet hole to guide the air around the tube, the downstream side became
> a stagnant air pocket and the temperature shot off-scale.
>
>
> --
> 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
> Editor, 'The VHF/UHF DX Book'
> http://www.ifwtech.co.uk/g3sek
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