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Did the TEK factory have the fan suck air in or blow it out the back?
kevin

All I have ever seen draw in at the back. The air passes through the filter first before being delivered to the interior of the cabinet. Here is a bit of fan/blower trivia: A propellor fan needs maximum power when the air flow is impeded or blocked, a centrifugal requires minimum power when the air flow is blocked. The motors on propellor fans are usually cooled by the air flowing over them. A clogged filter not only overloads the motor, it deprives the overworked motor of cooling. Keep the filters clean and free flowing. Don't ignore the filter if it is missing, high voltage attracts dust from unfiltered cooling air, which can cause a flashover.

Bruce Gentry, KA2IVY

The 485 has the wonderful temp controlled Siemens motor and impeller design
fan. It draws the air in through the enclosure and expels it at the back of
the scope.

The 7854 (and maybe other 7000 series scopes) draws air in through strategically placed perforations in the covers (top and sides but mostly bottom) and blows it all out the back. There are no filters. The fan is a propeller type.

Regards, Cliff Carrie
________________________________
From: [email protected] <[email protected]> on behalf of greenboxmaven via Groups.Io <ka2ivy@...>
Sent: Monday, August 19, 2019 8:58 PM
To: [email protected] <[email protected]>
Subject: Re: [TekScopes] Fan direction on TEK485

All I have ever seen draw in at the back. The air passes through the
filter first before being delivered to the interior of the cabinet.
Here is a bit of fan/blower trivia: A propellor fan needs maximum power
when the air flow is impeded or blocked, a centrifugal requires minimum
power when the air flow is blocked. The motors on propellor fans are
usually cooled by the air flowing over them. A clogged filter not only
overloads the motor, it deprives the overworked motor of cooling. Keep
the filters clean and free flowing. Don't ignore the filter if it is
missing, high voltage attracts dust from unfiltered cooling air, which
can cause a flashover.

Bruce Gentry, KA2IVY


On 8/19/19 8:28 PM, Kevin Oconnor wrote:

Did the TEK factory have the fan suck air in or blow it out the back?
kevin

The 485 has the wonderful temp controlled Siemens motor and impeller design

fan. It draws the air in through the enclosure and expels it at the back of
the scope.

Quite the opposite: The fan will draw in air at the back of the 485, and you can feel the warm air coming out of the case to the left and right front sides of the front panel. BTDT, just last week I wanted to stop my workplace 485 humming loudly. As an extra, you might ask yourselves why the aluminum mesh filter and the foam filter is on the back side of the instrument - because the air enters exactly there.

Regards, Jochen DH6FAZ

One reason for positive pressure cooling is that it reduces dust. Air is draw in through the filter which removes the dust (one hopes) and blows it through out the chassis.
However, positive pressure works when the chassis is designed for it, otherwise cooling may be better with a fan blowing out to exhaust warm air. Positive pressure design is not trivial; you want the greatest cooling where the greatest amount of heat is produced but don't want that air heating up the rest of the chassis. The chassis must be sealed well enough to control the air flow. Sometimes the blower must be some distance away from the hot spots.

--
Richard Knoppow
dickburk@...
WB6KBL

On Tue, Aug 20, 2019 at 5:54 PM Jokken Feldhaar <jochen_feldhaar@...>
wrote:

The 485 has the wonderful temp controlled Siemens motor and impeller

design
fan. It draws the air in through the enclosure and expels it at the back of
the scope.

Quite the opposite: The fan will draw in air at the back of the 485, and
you can feel the warm air coming out of the case to the left and right
front sides of the front panel.

Hey Jochen,

you are absolutely right, I just went to look at my 485. My apologies for
the (my) confusion. It does have the Siemens brushless motor though :).

I was thinking of the 2465, which has the same motor and an impeller, but
the opposite airflow direction. The 2465 most certainly draws air in
through the case through strategically placed perforations in the case,
which are placed over some of the hybrids, and blows it out the back
Both the 485 and the 2465 are as close to silent as makes no difference
though, which is a great feature in any scope.

Siggi

Doesn’t that contradict post 1478-2b?

Sent from kjo iPhone

Ok. Thanks all. Confirmed 485 sucks. In at back?

Sent from kjo iPhone