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
|