> Without the cover - so the air was blowing onto the upstream side of
> the tube, but then going wherever it wanted - the upstream side stayed
> at 220-230C but the downstream side very quickly went off-scale.
>
> With the cover, the total airflow decreased due to the additional
> back-pressure (you could hear the fan rpm drop)... but the upstream
> temperature stayed pretty much the same as before, and the downstream
> temperature came down dramatically - it was maybe about 50C higher
> than the upstream side (it only just went off-scale, but much more
> slowly than before).
On 60Hz the EBM fan specified for that unit is fast enough to keep
even the glass below 200C at rated dissipation, but only with the
cover on.
By the way, it is permissible to allow the envelope away from the
seal exceed the rated seal temperature. The seals are the critical
area you should test.
I'm not sure how it would behave on 50Hz.
73, Tom W8JI
W8JI@contesting.com
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