On 2/3/2014 3:09 AM, Gary Smith wrote:
Before working the 160M contest last week I put the digital
temperature probe I use for cooking meat in the oven into the air
flow from my amp just to see what temps I generate when running a
frequency.
Build the simple manometer shown in the handbook. If you are running
the required pressure, then yoy are running the require air flow.
Measure right across the tube to get the most accurate. Find what
blower speed gives the required pressure. Then back off to where the
noise is comfortable. Use a sensor in the output air so when the temp
rises it can kick into high blower. Use a couple sensors to give more
leeway. Normal, high, and afterburner. IOW. If a little more speed
will keep the temp in range on SSB, there is little reason to run more
pressure than required, but when heavy duty work like digital or slow
scan heats things up, then go for max cooling,
With 2 tubes you have twice the area and half the power per tube and
less noise. That is unless the urge to "use" both tube can not be
resisted<:-))
73
Roger (K8RI)
The room temp is 68F and at idle the temp sits at 82 as it exits the
amp. Running pretty steady CQ and replying, the air temp gets up to
142 when I'm hot (pun intended) & heavy into the contest. According
to the specs n the Eimac sheet it gives the amount of air that needs
to be moved to handle 1500W anode dissipation as 38CFM to hold the
temperature below 225C (437F) at 50C (122F) ambient temp.
http://www.ok1rr.com/tubes/eimac/3CX1500A7.pdf
Since they don't give air exit temps in the data I don't know if my
142F means I need to speed up the blower or if all is well as is. I'd
rather keep the noise level low but would rather have more fan noise
than a burnt tube.
Idears?
73,
Gary, KA1J
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