As many of you know, I teach One-Day Tech classes. At the start of each class, I go over the following to help focus students on what to keep in mind when taking the test.
For the Tech test, the focus is on rules and safety. It is not very technical. Having said that, there are three technical topics that you need to know:
- Ohm’s Law,
- how to calculate power, and
- the relationship between frequency and wavelength.
The basic formula for Ohm’s Law is voltage (E) equals current (I) times resistance (R), or E = I x R. On the test, there are several questions where they give you two of the values and ask you to calculate the third. If you’re asked to calculate the current, you use the formula, I = E / R. If you need to calculate the resistance, use the formula R = E / I.
How to Calculate Power
The formula for calculating power is power (P) = voltage (E) times current (I), or P = E x I. To calculate the current drawn, when given the power being consumed and the voltage applied to the circuit, use the formula I = P / E.
Relationship Between Frequency and Wavelength
There are several questions that require you to calculate the wavelength of a signal or some fraction of the wavelength. The reason for this is that antennas are often a fraction of a wavelength.
The formula that describes the relationship between frequency and wavelenght is wavelength in meters = 300 / frequency in MHz. One question asks for the approximate length of a quarter-wavelength vertical antenna for 146 MHz. To figure that out, you first calculate the wavelength:
wavelength = 300/146 = 2.05 m or about 80 inches
One quarter of 80 inches is 20 inches, and the antenna will actually be a little bit shorter than that because radio travels more slowly in wire than it does in free space. The correct answer to this question is 19 inches.
That’s all there is to the technical part of the test!
There are lots of questions on the test about operating safely and being safe when working on antennas. My advice when answering these questions is to always choose the most conservative answer. The two exceptions are when asked what is the lowest voltage and current that can hurt you. For these questions, the correct answer is the second lowest choices.
There are lots of questions about what to do in emergencies. There are two things to keep in mind when answering these questions:
- You should do whatever you can to help someone who is in an emergency situation.
- You can even break the rules to help someone in an emergency situation. This includes operating on frequencies you are normally not allowed to operate on and communicating with other stations in other radio services.
Here are a couple of other miscellaneous tips:
- The answer is ‘D.’ If one of the answers to a question is, “D. All of these answers are correct,” chances are that is the correct answer. There are 18 questions with this option, and of those 18 questions, there are only two questions–T3B06 and T5B03–where that is not the correct answer.
- Long-Answer Rule. Where one answer is a lot longer than the other options, chances are that this is the correct answer. I haven’t done an exhaustive study of this, but when one answer is very long, take a good, hard look at it.
That’s all I have. What tips do you have for passing the Tech test?