[Test-Equipment] Re: Bird 43 Problem

[Eric Lemmon]

Bill,

I suspect that the contacts need to be cleaned.  Use a Q-Tip or similar
swab moistened with alcohol to clean both the bore of the 43 and the
contact in the side of the bore.  Inspect the contact to be certain that
it is neither loose nor bent.  Also, clean the outside of the slug and
both contacts.

If you reverse the input and output connections to the 43 meter, does
the meter now read forward power when the slug is in the "reverse"
position?  That is, when the arrow on the slug points to the antenna,
even though the meter is "backwards."

Since genuine Bird slugs are precision devices, as is the meter itself,
any differences in forward and reverse connection would likely be due to
misalignment of the slug within the bore.  If the slug retention catch
has been engaged, that is very unlikely.

One possibility is that the side (stationary) contact spring has been
misaligned, due to improper slug insertion.  This tidbit of information
came to me years ago from a Bird tech support person, and does not
appear in my Bird 43 manual:  The slug should be inserted into the bore
with the arrow pointing up (toward the meter) and with a slight turning
motion.  This ensures that the side contact does not "catch" on the slug
contact during insertion.

If you look at a slug that has been in use for a while, you should see a
faint line on the side, where the bore side contact rubs on the slug as
it is turned between forward and reverse positions.  This line should be
exactly in line with the slug contacts; if not, the side contact in the
line section should be replaced.

My Model 43 meter is over 25 years old, and still works perfectly.  I
attribute its long life to careful treatment, always returning it to its
carrying case when not in use, with the slug centered to damp the meter,
and never touching the slugs except with the knurled knob.

73, Eric Lemmon WB6FLY

Bill Pancake wrote:

> Any ideas why my Bird 43 wattmeter will read correctly in the "forward
power" slug position but NOT in the "reflected power" position?
>
> The slug (element - 100H) is working perfectly and meter works
perfectly. Does it have something to do with maintenance of the thruline
section? Have tried two different (one new - one used) 100H slugs - same
problem, no reflected power reading.
>
> Another wattmeter (Drake W-4) shows reflected power in my test setup.
Any suggestions appreciated. Tnx, Bill, wd0x