HP Boat Anchor Fans

[John Devereux]

Hi,

Has anyone tried replacing the fans of some of the older HP test gear?

They make a lot of noise, can't help thinking there are better - or at
least quieter - ones to be found thanks to the PC market.

 

[Phil Hobbs]

Hi,

Has anyone tried replacing the fans of some of the older HP test gear?

They make a lot of noise, can't help thinking there are better - or at
least quieter - ones to be found thanks to the PC market.

Most of the ones I've taken apart are 120V.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[John Devereux]

Once an HP fan, always an HP fan. Looking to join an HP fan club?

Hint: I like HP test equipment.
<http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html>

I am approaching that level of excess, if you include some Tek and
Keithley stuff too

Do you mean very old equipment, or slightly old equipment? The really
old fans will run forever. Real bearing, that can be lubed. Brute
horsepower that will turn the blades even when buried in muck and
packed with dust. Genuine intake filters. I don't recall ever
replacing a really old fan. The not so old fans are more "modern"
using plastic frames, bushings, DC power, minimal horsepower, and
marginal filters. While not as good or reliable, they do make less
noise.

I guess I must have a mixture, but all pre-agilent stuff.

What you'll probably find is that a fan that moves the same amount of
air in CFM (cubic feet per min), will make about the same amount of
noise. The only way you're going to reduce the noise is to use a
smaller or slower fan, which I don't recommend. Ear pads are cheaper
and easier.

With computers, IME the fans tend to get quieter as they get bigger
(larger diameter). Most of the noise on the HP fans sounds to me more
like the motor or bearings. Rather than air movement. A moaning sort of
whine, rather than a whooshing.

I don't think you will have good results replacing the big fans with a
PC style fan. They just don't move enough air (CFM), have problems
with the bushings, and clog easily. They also don't do well with the
high internal heating found in some of the older HP test equip.
Something big by Rotron or other reputable manufacturer will probably
work, but I think you'll find it almost as noisy as the original.

Besides, modifying an HP instrument from stock is considered
sacrilege.

Oh yes I can see that too!

 

[Klaus Kragelund]

Hi,



Has anyone tried replacing the fans of some of the older HP test gear?



They make a lot of noise, can't help thinking there are better - or at

least quieter - ones to be found thanks to the PC market.

A collegue of mine changed the fan on the E36xx series. Or rather he just added a control to shut it off if it was running cold (why they did not add that it the first place I don't know). AFAIC he had to add special circuitry since it would detect fan failure.

Most HP gear is great, but some are funny like the fan operation. Other special features, like that on the HP33120A function generator it is not possible to turn the output off. And that duty cycle is limited from 20 to 80%. Tsk tsk..

Cheers

Klaus

 

[hamilton]

A collegue of mine changed the fan on the E36xx series. Or rather he just added a control to shut it off if it was running cold

I am sure HP is like any other big company.

When engineering is finished with it and throws is over to
manufacturing, things will get changed.

"Oh, this cheaper fan will be fine".

And a fan will not get pushed back to engineering for re-evaluation.

hamilton





.. AFAIC he had to add special circuitry since it would detect fan failure.