Tests for power on a 2m antenna

Caution! To avoid dangerous RF exposure, these tests are to be carried out using a maximum power of 5W only. A 2m HT is quite safe for the purpose.

The ability of a neon lamp to glow in the presence of an electromagnetic field made it a handy RF indicator of yesteryear. Many a handie talkie (HT) was tested by just holding a NE-2 near its whip antenna.

Curiosity led to a search of the junk box for a NE-2 but a different type, having plate electrodes, was found (see inset).

Power was applied and the antenna probed with the neon lamp. A static-charged plastic bag, placed in between , helped trigger the neon lamp.The ensuing red glow was sustained by the RF energy. The plastic bag may not be required when dry weather and synthetic clothes make it more conducive for the test.

Neon Lamp Test on J-Pole Antenna

At high voltage points the neon continued to glow even when moved away from the antenna.

Neon Lamp Test on Rubber Ducky

A more reliable method is to use a dipole as a pickup and a 6.3V-150mA dial lamp as the indicator.

My version of the pickup has two 21" telescopic whips fixed on a wooden strip, with the dial lamp soldered in between. It's quite convenient to push the telescopics in and fold them for storage.

Dipole-lamp pick-up - folded

With only 3.5W from my HT, and the dipole length adjusted to ½λ, the lamp glowed to more than full brilliance at a good distance from the antenna.

Dipole-lamp test on J-Pole antenna 

______________________________

'Wire Slim Jim' for 2m

This is a 'Wire Outside PVC' Slim Jim for 2m. It was made using enamelled copper wire and a vacuum cleaner nozzzle!

2m Wire Slim Jim

The wire ends and the BNC connector were fixed with self-tapping screws. The feed points were

connected to the BNC using the same wire. Water ingress points were sealed off with 'Araldite'.

An SWR of 1.5:1 was realized.

Related post: 2m J-Poles and a Slim Jim
______________________________