Thanks to all for your comments on the faulty 100-250 Mhz 100 watt
Bird Slug. (100c)

My ham friend and I made separate calls to Bird Corporation and talked
to two Bird Corporation technicians Monday morning. Both believe it is
a deteriorated diode that is causing the lower readings. The slugs
are rated at +/- 5%.

The pot underneath the label tab is for recalibration purposes and
and has to be adjusted carefully. However it will not correct a bad
or deteriorating diode. They will recalibrate for $50 but no longer
repair slugs. A new slug is $75 plus shipping from their distributors.
Slightly less if you have an account with them.

Again thanks for all of your inputs.
73 K3BEQ