[AMPS] Blower on a GS35b Amplifier..??

[Steve Thompson]

Sorry I'm late in on this, been away for a week.

In message <3549D424.C4BC5527@iaehv.nl>, John Peters <pe1ogf@iaehv.nl>
writes
>Hello all,
>
>I'm just new on this reflector, perhaps one of you can help me with the
>following question :
>
>While reading some old DUBUS magazines I've seen several GS31 and GS35
>PA's some were cooled with a big size computer blower (Axial blower) is
>this realy sufficient ????

Ordinary fans are never up to the job. Some very unusual axial fans can
produce pressure (I once used a 4" fan turning at 22,000 rpm to get
100cfm at 2" water), but these are very rare, expensive and VERY noisy. 

>it realy must be possible but how long will
>it last.. For Example if there is realy 1500W of heat on the anode will
>the tube survive a contest with such a blower ?? anyone any experiance..
>If I complare with my GS31b PA where there is "only" 1000W of heat
>produced there is a huge Radial blower.. Even 1m above the air outlet I
>can ballance a pice of paper on my hand.. Is this blower overkill ??

Within reason I think it's impossible to overcool a valve. 

>
>PSE any info will be more than welcome.. Need it for the 144MHz EME/MS
>amplifier for the HBo Expedition.
>

If you are unsure about blower capability you might do worse than
measure the outlet air temperature, assuming it is reasonably direct
from the anode; 100 deg C is a good upper limit. It's better to measure
airflow with an anemometer or large bin bag.

Steve

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