I have both a 492 and a 494P and both run quite hot (measured with my finger). I did not put a thermometer on it, but 56 degrees C sounds about right, I can lightly touch it but would not want to press my finger against it.
Over here, this is the season where a little bit more heat in the shack is a good thing :-) The 494P is the second best shack heater in my stable, at 170W. The HP 5370A is close behind at 160W. The best is the HP 8673M at 200W.
I think the small fan blowing over the heat sink makes sense, I am considering adding one to the rack where the instrument resides.
If you have ever opened the instrument, the cooling fan is quite small and it's not clear where the air circulates, but one thing is sure, not much blows over the heat sink. Some air may find its way through the holes, but I have not been able to feel any air flow.
On the other hand, the heat sink supports power transistors that can run at 80 degrees or more pretty much forever, so there should not be real concerns for the reliability of the instrument (I think that should be established by now, these instruments have great reliability), but it is a concern for handling it when it has just been powered.
Didier KO4BB
Gerald wrote:
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Hi all,
I felt the rear if my Spectrum Analyser 492BP. I can not touch the metal strip just above the plastic cover it's that hot. So I got out my Fluke IR Thermometer and the surface read 56 Degrees C, wow.
I have discussed this with other people before, however it is now summer down here and not being able to touch the rear in a hotter climate is of real concern.
I have checked the entire unit from top to bottom, AC ripple, excessive current consumption on each supply rail put in a new fan, added a second mini fan internally, I simply can not fault the power supply and the unit.
I am keen to get as many views, termperature values and advise on this subject matter from users of the 492BP's or 494P's. Seriously, I now have to run the SA with a small PC fan blowing air over the rear.
Happy new year to every one.
Regards
Gerald
