Venkat,

We can prolly be of greater assistence if you can add the following information

Manufacture and Model of your Inverter machine

Material type and thickness you intend to join

The reason you feel High Frequency is required above and beyond the regular capabilities of your machine.

Most manufactures supply after market HF boosters but I've never heard of one being needed to assist an inverter in the area of arc starting (which is what I am assuming you require the HF for), even with leads approaching 100 feet (30 m) in length. This makes your question interesting...