Wednesday, December 22, 2010

Lesson 19: General Class Exam Course G4E

Hello again!  Here is lesson 19 covering HF mobile operation and emergency power sources.  These questions are fairly straight forward. 

As far as privileges go, there is really no difference between mobile station operation and any other type of amateur station.  Mobile HF operation does have some peculiarities and limitations.  The primary limitation of mobile operation is the limited size of the mobile antennas.  It is not practical to drag a half-wave dipole for 80 meters on top of your car.  There are compact antennas designed specifically for mobile operation, but no matter how well the antenna is designed, it will never work as well as a full sized antenna.

This section also deals with alternative energy sources such as solar, wind, and gasoline generators.  For the generator power questions, the theme is safety.  Whenever you operate a gasoline powered generator, make sure the area is well ventilated.  Carbon monoxide poisoning kills a lot of people every year!  Even when operating a generator outside, precautions must be takes to ensure exhaust fumes are not entering the home, tent, or shack.   

There is one question that needs to be memorized:

- The common power produced by a photovoltaic (solar) cell is 0.5 VDC.

That's about it.  If you have any comments, questions, or suggestions, please feel free to leave them in the comments box.  Until next time...


Tuesday, December 21, 2010

Lesson 18: General Class Exam Course G4D

Here is lesson 18!  This lesson covers the G4D questions dealing with speech processors, connectors, and S-meters.  There is some memorization in this lesson, but it is not too bad.  The information you need to focus on is:

- Speech processors increase the average power of your signal, but not the PEP.
- An S-meter reading of 20 dB over S9 is 100 times stronger than a signal at just S9. (I dorked up the question in the video.  Disregard the formula.)
- A Type-N connector is a moisture resistant RF connector that is useful up to 10 GHz.
- A DB-9 connector is a good connector for a data serial port.
- UHF connectors is a family of RF connectors that have nothing to do with UHF.  They are useful up to 150 MHz.

And that's it!  If you have any suggestions, comments or questions, please feel free to leave them in the comments box.  Thanks!


Monday, December 13, 2010

Lesson 17: General Class Exam Course G4C

Here is lesson 17!  This lesson covers the G4C section of questions from the exam pool dealing with interference and grounding.

There are a few items that you may want to focus on in this section.  There are a couple of questions that deal with filters used to prevent RF interference (RFI).  Sometimes the speaker wires of a stereo can pick up signals from your transmitter and interfere with the stereo speakers.  A way to limit the interference to the speakers is to install a Bypass Capacitor along the speaker wires.  The other type of interference common between hams and consumer electronics is interference with a nearby telephone.  For this question on the exam, the solution you are looking for is to install an RFI Filter at the affected telephone.

A common theme in the questions dealing with station grounding is to keep the ground wire from your station to the ground as short as possible.  Long ground wires may resonate like an antenna at certain frequencies.  This prevents the ground wire from doing its job and sending unwanted RF energy to the ground.  If this is happening it can cause RF hot spots to build on your station equipment possibly giving you an RF burn if you touch the wrong thing.  Keep ground wires short!

Please leave any comments, suggestions, and questions you may have!


Monday, December 6, 2010

Lesson 16: General Class Exxam Course G4B

Here is lesson 16 covering the G4B section of questions form the question pool.  This lesson primarily deals with test equipment.  The lesson is straight forward, but I will give you a run down of the various test equipment covered.  Remember, these are very simplified definitions for the intent of identifying the correct answer on the exam.

- An Oscilloscope is used to measure waveforms. 
- A signal tracer is used to identify inoperative circuits in a receiver.
- A noise bridge measures impedance and is connected between a receiver and an antenna of unknown impedance.
- A field strength meter will measures RF field strength and can be used to measure RF output.
- A dip meter measures the resonant frequency of a circuit.

Until lesson 17...


Thursday, December 2, 2010

Lesson 15: General Class Exam Course G4A

Welcome back!  Here is lesson 15 covering the G4A questions of the General Class question pool.  This lesson deals with Digital Signal Processors, vacuum tube RF power amplifiers, and neutralizing circuits.  This lesson is fairly straight forward with the exception of the questions dealing with the vacuum tube RF power amplifier adjustments.  Unless are already familiar with these amplifiers, the answers may be a bit of a mystery.  Here's the information that I recommend you memorize:

- The reading on the plate current meter of a vacuum tube RF amplifier which indicates correct adjustment of the plate tuning control is a pronounced dip.

- The correct adjustment for the "Load" or "Coupling" control of a vacuum tube RF power amplifier is the maximum power output without exceeding maximum allowable plate current.

Please feel free to leave any comments, suggestions, or questions!  Until the next lesson...