## Thursday, July 15, 2010

### Lesson 31: Technician Class Exam Prep T9A

Here is lesson 31 and the T9A questions from the exam question pool.  The T9A questions deal with antennas.  You may have the best transceiver on the market, but if you have a bad antenna the quality of the transceiver won't mean a thing.  You will want to familiarize yourself with some basic antenna principles before you try to get on the air.  You at least need to know the basic principles for building a dipole antenna.  The exam question review will help, but they really don't go into the detail you need.  A good book is Basic Antennas: Understanding Practical Antennas and Design published by the ARRL.  It breaks down the basic theory and gives some good project ideas.

There are two formulas you will need to know for the exam.  The first is to find the length of a quarter wave vertical antenna in inches.  The formula for this is:

Length(in) = 12(234/freq(MHz))

The other is to find the length of a half wave dipole in inches.  The formula for that one is:

Length(in) = 12(468/freq(MHz)

For once, these formulas come in handy for everyday Ham use, unlike some of the others.

Until next time...

73,
Andy
KE4GKP

1. Thanks Andy when will you up date your general class because i want to jump in to it because i want it before my13 birthday
KPB