[Towertalk] re 402BA

[Peter Forbes]

Wayne N2WK

A common fault which develops in the 402BA is a puncture hole through the
plastic cap which sits on the driven element centre and insulates from the
boom.  A carbon track develops and will break down at a certain power level.

The cause is usually (1)  running too much power off frequency from its
design frequency or (2)  a lightning strike (or near by surge) which creates
enough voltage between the driven element and the boom to puncture the cap
which is about 3 mm thick.

Solution:  purchase and replace the plastic cap.

Interestingly, the same caps are used on the TH3/TH6/TH7 series, but the
beta match which grounds the elements to the boom, usually protects the
caps.

Good luck

Cheers


Peter Forbes  VK3QI