[Amps] Air temps leaving the amp.

[Roger (K8RI)]

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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