Topics

400 series air filters

Edward Prest
 

I believe the 465, 475, 485 have air cleaners/filters with the fan. The 466 does not. (466 blows out the back).
Why the difference?

Chuck Harris
 

It is easier, and much lighter weight to cool an
instrument if it can get fresh air through holes
found here and there in the instrument cabinet.

That is what is usually done when the fan draws
a gentle vacuum on the insides of the case.

But, it is much dirtier as those holes vacuum up
the dust in the surrounding environment, and
deposit it throughout the instrument.

When the air comes through a filter and blows
into the case, ducting paths must be figured out
that distribute the air from the fan to where it
is needed. That requires calculations, and quite
a bit of extra sheet metal.

-Chuck Harris

Edward Prest wrote:

I believe the 465, 475, 485 have air cleaners/filters with the fan. The 466 does not. (466 blows out the back).
Why the difference?

petertech99h
 

Chuck Harris,
I agree, but I don't think I've seen anything like extra metal or plastic to duct
air thru the scopes.
2 years ago I picked up a MIG welder, and noticed how the diodes would heat and the welder would stop for a
while, there was a fan cut-out complete with screw holes, but no fan.  So I stuck in a fan, blocked some
side vent holes near the fan and fabricated a fibreglass baffle to suck all the air across the diode heatsinks after
entering thru existing vents near the front! Worked like a charm, no real duty cycle issues left!
Question is, on the 400 series Tek, where are the hot spots? lol!!
'73 Guys!
Pete

On Saturday, March 7, 2020, 12:31:08 a.m. EST, Chuck Harris <cfharris@...> wrote:

It is easier, and much lighter weight to cool an
instrument if it can get fresh air through holes
found here and there in the instrument cabinet.

That is what is usually done when the fan draws
a gentle vacuum on the insides of the case.

But, it is much dirtier as those holes vacuum up
the dust in the surrounding environment, and
deposit it throughout the instrument.

When the air comes through a filter and blows
into the case, ducting paths must be figured out
that distribute the air from the fan to where it
is needed.  That requires calculations, and quite
a bit of extra sheet metal.

-Chuck Harris

Edward Prest wrote:
I believe the 465, 475, 485 have air cleaners/filters with the fan. The 466 does not. (466 blows out the back).
Why the difference?

Chuck Harris
 

Sometimes you have to look at middle partitions,
and covers to card cages and think of what else
they do. Baffles, and ducts are all over the
place in just about every scope I have ever
seen. Particularly those that have rear filters
and blow the air through the inside of the scope.

-Chuck Harris

petertech99h via Groups.Io wrote:

Chuck Harris,
I agree, but I don't think I've seen anything like extra metal or plastic to duct
air thru the scopes.
2 years ago I picked up a MIG welder, and noticed how the diodes would heat and the welder would stop for a
while, there was a fan cut-out complete with screw holes, but no fan.  So I stuck in a fan, blocked some
side vent holes near the fan and fabricated a fibreglass baffle to suck all the air across the diode heatsinks after
entering thru existing vents near the front! Worked like a charm, no real duty cycle issues left!
Question is, on the 400 series Tek, where are the hot spots? lol!!
'73 Guys!
Pete

On Saturday, March 7, 2020, 12:31:08 a.m. EST, Chuck Harris <cfharris@...> wrote:

It is easier, and much lighter weight to cool an
instrument if it can get fresh air through holes
found here and there in the instrument cabinet.

That is what is usually done when the fan draws
a gentle vacuum on the insides of the case.

But, it is much dirtier as those holes vacuum up
the dust in the surrounding environment, and
deposit it throughout the instrument.

When the air comes through a filter and blows
into the case, ducting paths must be figured out
that distribute the air from the fan to where it
is needed.  That requires calculations, and quite
a bit of extra sheet metal.

-Chuck Harris

Edward Prest wrote:
I believe the 465, 475, 485 have air cleaners/filters with the fan. The 466 does not. (466 blows out the back).
Why the difference?





Tim Phillips
 

from Tim P (UK)
re air-flow generally, on 7000 mainframes and TM cages with fans, should
any unused plug-in positions be blanked off?
If I am working on a 500-series plug-in on an extension cable, I always
put a piece of cardboard across the front of the plug-in compartment to
prevent the air from just blowing out of the hole.
Also, for the 7000 / 5000 series, the various models have different
perforation patterns in the covers, and some covers. have 'FRONT' printed
on them.
Tim

On Sun, 8 Mar 2020 at 05:43, Chuck Harris <cfharris@...> wrote:

Sometimes you have to look at middle partitions,
and covers to card cages and think of what else
they do. Baffles, and ducts are all over the
place in just about every scope I have ever
seen. Particularly those that have rear filters
and blow the air through the inside of the scope.

-Chuck Harris

petertech99h via Groups.Io wrote:
Chuck Harris,
I agree, but I don't think I've seen anything like extra metal or
plastic to duct
air thru the scopes.
2 years ago I picked up a MIG welder, and noticed how the diodes would
heat and the welder would stop for a
while, there was a fan cut-out complete with screw holes, but no fan.
So I stuck in a fan, blocked some
side vent holes near the fan and fabricated a fibreglass baffle to suck
all the air across the diode heatsinks after
entering thru existing vents near the front! Worked like a charm, no
real duty cycle issues left!
Question is, on the 400 series Tek, where are the hot spots? lol!!
'73 Guys!
Pete

On Saturday, March 7, 2020, 12:31:08 a.m. EST, Chuck Harris <
cfharris@...> wrote:

It is easier, and much lighter weight to cool an
instrument if it can get fresh air through holes
found here and there in the instrument cabinet.

That is what is usually done when the fan draws
a gentle vacuum on the insides of the case.

But, it is much dirtier as those holes vacuum up
the dust in the surrounding environment, and
deposit it throughout the instrument.

When the air comes through a filter and blows
into the case, ducting paths must be figured out
that distribute the air from the fan to where it
is needed. That requires calculations, and quite
a bit of extra sheet metal.

-Chuck Harris

Edward Prest wrote:
I believe the 465, 475, 485 have air cleaners/filters with the fan. The
466 does not. (466 blows out the back).
Why the difference?







Chuck Harris
 

Any instrument that has a fan, or blower, situated so
that it blows air into the instrument's cabinet, will
have special partitions, and ducting inside the cabinet
to direct air flow to the proper points. If the case
has any unintended openings, they will likely disturb
the proper air flow, and some areas will get hotter than
normal.

The 7000 series scopes all seem to have fans that suck
on the case, and have cabinet holes strategically placed
over hot spots.

Most 7000 series scopes don't generate all that much heat
except in the power supply, which is serviced directly by
the fan. The 7854 may be an exception.

It is probably recommended to plug unused plugin holes, but
I don't see that leaving them open causes 7000 series scopes
any problems in ordinary room temperatures.

-Chuck Harris

Tim Phillips wrote:

from Tim P (UK)
re air-flow generally, on 7000 mainframes and TM cages with fans, should
any unused plug-in positions be blanked off?
If I am working on a 500-series plug-in on an extension cable, I always
put a piece of cardboard across the front of the plug-in compartment to
prevent the air from just blowing out of the hole.
Also, for the 7000 / 5000 series, the various models have different
perforation patterns in the covers, and some covers. have 'FRONT' printed
on them.
Tim


On Sun, 8 Mar 2020 at 05:43, Chuck Harris <cfharris@...> wrote:

Sometimes you have to look at middle partitions,
and covers to card cages and think of what else
they do. Baffles, and ducts are all over the
place in just about every scope I have ever
seen. Particularly those that have rear filters
and blow the air through the inside of the scope.

-Chuck Harris

petertech99h via Groups.Io wrote:
Chuck Harris,
I agree, but I don't think I've seen anything like extra metal or
plastic to duct
air thru the scopes.
2 years ago I picked up a MIG welder, and noticed how the diodes would
heat and the welder would stop for a
while, there was a fan cut-out complete with screw holes, but no fan.
So I stuck in a fan, blocked some
side vent holes near the fan and fabricated a fibreglass baffle to suck
all the air across the diode heatsinks after
entering thru existing vents near the front! Worked like a charm, no
real duty cycle issues left!
Question is, on the 400 series Tek, where are the hot spots? lol!!
'73 Guys!
Pete

On Saturday, March 7, 2020, 12:31:08 a.m. EST, Chuck Harris <
cfharris@...> wrote:

It is easier, and much lighter weight to cool an
instrument if it can get fresh air through holes
found here and there in the instrument cabinet.

That is what is usually done when the fan draws
a gentle vacuum on the insides of the case.

But, it is much dirtier as those holes vacuum up
the dust in the surrounding environment, and
deposit it throughout the instrument.

When the air comes through a filter and blows
into the case, ducting paths must be figured out
that distribute the air from the fan to where it
is needed. That requires calculations, and quite
a bit of extra sheet metal.

-Chuck Harris

Edward Prest wrote:
I believe the 465, 475, 485 have air cleaners/filters with the fan. The
466 does not. (466 blows out the back).
Why the difference?