HAM’S LIFE

The rapid developing electronics field has a very close association with ham radio and I refer to other technologies to illustrate that the expediential advance in technology covers much more then just electronics.  It may be a stretch in the mind of some to link this with ham radio but in my thinking there is a connection.  

Saturday night I heard the last part of a radio talk show that apparently had a guest earlier in the show.  The guest, it would seem as I followed the call in discussion, believed that modern electronic technology came as result of a UFO crash in Roswell, New Mexico in July of 1947.  Now I can not prove nor disprove if a UFO crashed in Roswell or if any technology was learned from that craft if it did crash but I do not believe we need UFO conspiracy theories to understand modern technology advancements.

The Industrial Revolution is considered to have started around 1760.  Up to that time things did not change much.  When people wanted to go somewhere by land they walked, rode a beast of burden, or rode in some kind of wagon or cart drawn by such animals.  If they wanted to go by water they had to row or be wind driven.   Harnessed steam power change that.

The world started changing.  The change, sense that time, has continued to change at an accelerated rate.  Swifter means of transportation and greater productivity of factories prompted the need for faster and more efficient communications.

The word telegraph comes from Greek and means distant writing.  Though a few telegraph devices using electricity were developed prior to Samuel Morse’s telegraph but they died while Mr. Morse’s telegraph took root and grew.  The telegraph started the age of electronic communications in 1837. 

Just 40 years after Mr. Morse showed the world how to put messages on wire and send them long distances in a flash Alexander Graham Bell showed the world how to put the human voice on wire and send it over long distances. 

While the world of electronic communication was growing during 1800’s and early 1900’s other fields of technology also grew.  Accelerated development was happening in all fields Firearms, Electric lights, Internal Combustion engines, photography, and the list could go on. 

Nikola Tesla demonstrated a wireless telegraph in St. Louis, MO in 1893 but Guglielmo (Italian for William) Marconi made it to the patent office first with an economical and effective system that communicated more then just a few meters away.  It was 60 years (1837 to 1897) from when the first effective wire telegraph was patented until the first effective wireless telegraph was patented and it was 40 years from when the telegraph was invented until the telephone was invented but it was only 2 years from when the wireless telegraph was demonstrated until the wireless telephone was demonstrated.  1899 A. Fredrick Collins successfully made a voice transmission.

In 1906 Lee De Forest placed a grid in the vacuum diode and made it a triode he called an Audion.  The Audion had a little gain but it was not until about 1912   triodes with sufficient gain make an oscillator was able to be produced.  The vacuum tube was further developed.  It had more grids added and it was reduced in size.  Using the vacuum tube allowed transmitters to operate with a continuous wave (CW) on a specified frequency rather then the parasitic signal spread over a band.  Receivers could then use active devices rather then the passive units of prior days.    The little glowing marvel made it so that almost every home in the United States had at least one radio receiver in it by 1930.

In 1939 RCA released the AC/DC radio using the All American Five vacuum tubes and radios started appearing in several rooms in the home.  They could fit in packages small enough to sit on a book shelf, kitchen counter, or bed side night stand.  Soon many companies started selling these efficient, attractive, small, inexpensive, and very dangerous radios.  Compact battery operated vacuum tube radios were also being produced.  Automobiles with radios started showing up just after 1930.

By 1947 Television antennas were sprouting on the roofs of houses all across the United States. 

In 1925 Julius Edgar Liliendfield filed the first patent for a transistor in Canada.  The new transistor was very similar in operation to a Field Effect Transistor.  Because Mr. Liliendfield did not publish any research and his patent did not cite any examples of the device being constructed Oskar Heil was able to patent a similar device in 1934.

Though Bell Laboratories was not able to patent a working bipolar transistor prior to December of 1947 they had been working on the concept of a solid state replacement for the vacuum tube for several years before 1947.

Now all of this was prior to the events that happened in Roswell in July of 1947.

Looking at the technological developments that took place from the beginning of the Industrial Revelation until 1947 and noticing the accelerating advances in that technology and comparing it to the rate of acceleration sense 1947 personally I would say we are just about on target where we should be without the need of some extra-terrestrials technology input.     

Today it is hard to understand what it was like in the early days of ham radio. Even over the 47 years I have been a ham there have been so many changes that when I tell how it was when I started some of the newer hams sit wide eyed just as I did when hams from the days of spark gap told of their experiences.

The spark transmitter was very noisy when it was being used. There was the smell from the ozone produced by the arc. The arc created a very annoying light display when the transmitter was being keyed. For these reasons the radio transmitter was not a welcome resident in the average home so it became housed in a small out building in the backyard many times much like another small structure also found in the backyard which didn’t smell very well either. The term ham shack was attached to those small buildings and the term has stuck even though the station might be located in a corner of the living room.

A statement was made on the history channel that the vacuum tube had to be invented before the radio could be invented. The logic behind the statement was that oscillators could not be made before amplifiers and it is true that oscillators could not be built before amplifiers but radio communications predates the use of these little glowing marvels as amplifiers by over 20 years. A spark gap and a coherer detector started it all off. Later the Peroxid of Lead detector came into being followed by many others including the Electrolytic Detector, the Barretter Carborundum Detector, the Silicon Detector, the Perikon Detector, and the Galena Detector, the last three could be lumped together and called a crystal detector. All of these preceded the use of the vacuum tube.

Though they precede the use of the tube they do not precede the vacuum tube itself. The summer of 1895 is considered the beginning of radio communications when Guglielmo Marconi was able to transmit and receive a signal over a distance of 1.5 kilometers (approx. 1 mile). The vacuum tube history began in 1883 when Thomas Edison, while trying to improve the incandescent light, discovered when he placed a small metal plate in the glass envelope of the light and attached the metal plate to a positive charge while the negative charge was on the filament electric current would flow across the vacuum inside the envelope. This came to be known as the Edison Effect but Edison did nothing more with it. He did not believe it to be of any value.

In 1904 Sir John Fleming found he could use the Edison Effect to detect radio signals. So over the 9 years between Marconi’s invention and Fleming’s discovery the vacuum had no connection to radio. It was not until 1915 when Lee DeForest placed a grid inside the diode between the filament and the plate that amplification was possible. With the invention of the Audion, the first name for the vacuum tube, true CW became possible. The Audion later became known as the Fleming Valve which it is still called in many countries but in the United States of America it is called a vacuum tube.

Not only did it provide the necessary essential to make oscillators and detectors but amplifiers and mixers which allowed the superhetrodyne radio.

It was these little glowing marvels that bridged the road between the wide band, short range, loud smelly spark, with insensitive passive detectors and the present solid state DX in a box radios.

Reginald Aubrey Fessenden is believed to be the first person to make a wireless voice transmission. Fessenden demonstrated the possibility of transmitting voice on December 23, 1900 by the process, which at that time was only a theory, known as heterodyne principle, the combining of two signals to form a third signal; he did that by using a spark-gap transmitter modulated by a carbon microphone, amplifiers had not yet been invented. His voice was heard over a distance of about 1.6 kilometers (one mile).

1907 Lee De Forest’s added the grid to the already existing diode vacuum tube to produced the triode tube he called an “audion”. The audion allowed for amplification. By the use of positive feedback in an amplifier the triode can be used as an oscillator. The oscillator made a single frequency continuous wave transmission possible. Amplitude Modulating the continuous wave signal with voice produced a far superior quality voice transmission to that provided by Fessenden’s spark-gap transmitter. FM did not come into existence until 1933.

The AM signal was and still is produced by the same principle Fessenden used in 1900, the heterodyne principle. A modulator is an audio amplifier which is connected in such a way as to control the output of a Radio Frequency amplifier. This will cause the two frequencies to be mixed together and produce not a third and a fourth frequency. When two frequencies are mixed together in a non linear circuit they will produce an output which will include the sum and the difference of the two frequencies. If a 4 MHz signal is Amplitude Modulated with a 1 KHz signal there will be a 4.001 MHz signal and a 3.999 MHz signal added to the already existing 1 KHz and 4 MHz signals. Because frequency difference between 4 MHz and 1 KHz is relatively large the 1 KHz signal is easily eliminated but 4 MHz and the two new frequencies, known as sidebands, are too close to be separated by conventional L/C circuits so there is a carrier of 4 MHz transmitted along with the two sidebands.

When received the signal is passed through a detector, a non linear circuit, which will allow the sideband frequency and the carrier frequency to mix thus producing a 1 KHz signal. (Do you see a problem? Stick with this series and see how the ARRL and other SSB advocates may not be telling the whole truth.)

When 100% modulation is achieved both sidebands combined equal one half the carrier’s power. So if a transmitter has 100 watts output un-modulated it will have 150 watts output when modulated at 100%. If the carrier and one sideband are removed the remaining sideband would be 25 watts. All the necessary intelligence for communications is contained in just one sideband. The audio is produced in the receiver as the sideband frequency is heterodyned against the carrier frequency or the reinserted carrier (BFO output).

Using the 4 MHz described above modulated at 1 KHz but filtering out all frequencies from 4 MHz and up only the 3.999 MHz, lower sideband, signal will be transmitted. Reinserting a 4 MHz signal at the receiver will produce a 1 KHz tone. If the carrier is modulated with a voice signal instead of a single frequency signal the principle will remain the same but multiple frequencies will be involved.

In AM if the operator speak softly so the carrier is only 50% modulated the power contained 1 one sideband will be 12.5 watts which means it will produce less output power in the detectors output and thus it is not as loud in the receiver’s speaker. It should also be noted that if the signal is reduced at the receiver either by reduction of transmitter power or by increasing distance the volume will be reduced.

How the carrier and undesired sideband are removed will be discussed tomorrow.

As a child I played with an electric train and discovered it produced a strange smell. Later I noticed other pieces of electrical equipment generated that same fragrance. The odor was from Ozone (O3) produced by the sparks of the brushes in the train’s motor and the also by the contacts on the tracks.

Ozone was discovered by Christian Friedrich Schönbein in 1840. He named it ozone after the Greek word for smell (ozein).

During the days of spark gap transmitters the term “ham shack” came into existence because the stations were housed in shacks outside the home. There were two main reasons for this; one was because of the noise generated by the spark and the other was because of the smell of the ozone produced by the transmitter.

Ozone fragrance is detectable at about .01 PPM. When the level reaches .1 to 1 PPM it will cause headaches, burning eyes, and irritation to the respiratory passages. Over 1 PPM it is considered very dangerous. The odor is not easily washed off and can linger on the flesh as well as in clothing.

Before amateur radio licenses were issued, when spark gap transmitters were the only kind of radio transmitters, Ed W6CC (now silent key) was an active ham radio operator though still in elementary school. He related the time when his teacher took him aside one day and asked him, “Why do you smelled so funny?”

So I guess in those days if someone said, “I smell a ham,” they may have been referring to something other then the smoked hind leg of a pig.