>
>2 wrote:
>>>Unfortunately that isn't at all relevant to forced-air cooling, where
>>>the airflow is very turbulent and the flow pattern is quite different.
>>>
>>?Ǩ fasten seatbelts
>>
>>>Air is blasted at the upstream side of the tube, cooling it well, but
>>>the flow breaks away from the surface half-way around to form a
>>>turbulent wake.
>>
>>?¨ Not with the quiet, slow speed fan in a SB-220, Ian..
>>
>All practical cooling fans create turbulence. It's easy to check with a
>streamer of smoke.
? If there was much turbulence in the SB-220, then the 3-500Z marking
ink would turn brown on the downwind side. However, the observed ink
color does not change with use -- unless the owner fails to oil the fan
motor bearings, and the motor eventually siezes and stops turning.
>>>The downstream side is only cooled by eddies in the
>>>wake, and there may even be negative pressure on the opposite side.
>>>
>>>There is absolutely no doubt that cooling is less good on the downstream
>>>side.
>>
>>?Ǩ The colour of the ink on the 3-500Z glass does not indicate this.
>>
>Thank you - that's the information I was asking for. Can you confirm
>that the ink is on the opposite side from the fan?
>
? I checked a 3-500z in my workshop, date-coded 8350. The ink was
nearest to pin 4 -- whiich is the downwind/leeward side in the V2
socket. However I recall using tubes whose marking ink was elsewhere.
>> >The only questions are: how much less good, and does it matter?
>>>That's why I was looking for separate evidence whether the color of the
>>>markings is dependent on the orientation of the tube.
>>>
>>?Ǩ Denial of reality - the greatest glitch in the human psyche. Alas.
>
>How very true for all of us. That's why I was asking for simple
>information about what the reality IS, in the SB-220 and the L4-B.
>
? The L4-B reportedly uses air-system (vertical flow)cooling. The
TL-922, the SB-220 and the Drake L7 use horizontal flow cooling.
later, Ian
- R. L. Measures, 805.386.3734, www.vcnet.com/measures.
end
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