Hi All,  For a steady, dependable vacuum source I use a tank-type
vacuum cleaner with about twenty feet of hose so I can minimize the
noise by "hiding" it far enough away in a nearby room for which I can
close the door.  (I used to use a spare Ampico pump but I found the
sweeper to be much better.)  I bought a piece of corrugated plastic
sump pump hose to make up the long length, but spare vacuum cleaner
hoses are sometimes available at Goodwill or Salvation Army stores
and they can be spliced together.

The most important feature of this arrangement is an in-line port for
varying the vacuum.  To make this I took a 1-foot piece of 1-1/2" PVC
pipe (size it so your hose fits tightly inside) and cut a 4" long,
narrow, tapered hole in the side, similar in principle to the hole
used on a typical tempo slide valve.  The hole is about 1/8" wide at
the small end and about 1" wide at the large end, and runs parallel to
the length of the pipe.  I covered this hole with an adjustable slider
made from a small piece of PVC cut out from the next larger size pipe.
This piece was made just large enough to cover the hole and was held in
place with a piece of 12 gage copper wire wrapped around the pipe.

In use, I hook up the device to be tested, turn on the sweeper, and
move the slider along the pipe, exposing some of the hole, until my
water manometer reads the correct vacuum that I need for the test.
(Note: The air rushing into the slider hole is noisy so this pipe
also needs to be located as far away from your testing site as is
practical.)  I also plug my sweeper into an extension cord with a foot
operated switch so I can turn the vacuum source on and off from my
workbench.

Pat DeWitt
Fort Wayne, Indiana