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.     

I delete about 100 comments for each one I accept because most of the comments are just to advertise their site and has nothing to do with ham radio.  If you read through the comments you will see that many of the comments I have accepted are probably for the purpose of drawing people to a site unrelated to ham radio but at least the comment had some substance.  There are also a lot of good comments.

Today as I was monitoring the comments I found one by Mike G which really attracted my attention.  The comment can be found on my post “THE DIFFERENCE BETWEEN HAM RADIO AND CB” (http://hamslife.com/?p=24).  Mike’s comment or actually questions were: “Were HAM radios used by the French resistance during WWII? Have they been successfully used in modern times, in countries where tyrannical gov’ts have taken over? How can a HAM radio be utilized successfully today if the USA were to collapse?”

The subject Mike brings up deserves, in my estimation, a lot more then just a simple response in the comment section.  Actually the area of ham radio and government subversion could fill a book but I won’t be writing a book here. 

During WWII there were commercially built ham radios on the market but nothing like the great number of units available today.  Many of the ham radios were home brew.  While I am sure many of these radios were converted to underground use by the French and other resistance groups and operated by licensed ham radio operators it needs to be understood that a radio station is only a ham radio when it is operated by a legally licensed amateur radio operator on an amateur radio frequency using amateur radio call signs.  If a licensed amateur radio operator uses his ham station under an encrypted call sign (call sign to reveal station identity to the station being called while concealing the station identity from others) to pass subversive information it technically is not a ham radio station at that time.  It may sound like I am splitting hairs but that is a hair that I believe needs to be split.

Radio transmitters and receivers which were constructed for amateur radio use have been used by many for good and bad.  Resistance groups such as the French Resistance have used them to combat tyranny and rebel armies have used them to provide communications.  Drug and other smugglers have used them to pass information.  Ham radios and ham operators have provided the world with instantly available operators and equipment to meet specific communications needs outside the normal amateur operations. 

The potential use of ham radio in event of a government collapse whether USA or another is certainly a difficult question to answer.  There was a television program series that illustrated this at least to some extent.  The program was “Jericho” and it can now be found on U Tube.  Jericho gave the title of that week’s program in Morse code. 

If the government collapse is do to an overthrow where nuclear weapons are used, such as in Jericho, most modern ham radios will become worthless.  Nuclear explosions produce huge EMF (Electro Magnetic Force) fields which will destroy all solid state devices.  Only those hams with vacuum tube equipment would still have working radios in event of a high level nuclear explosion.  Finding power to run these radios might prove to be interesting because most power plants use solid state devices in their monitoring equipment and the loss of these devices would cause a shutdown. 

I do believe that EMF is a serious threat to our world today. Thus we need to organize a group of ham radio operators with vacuum tube radios and means of providing power (generators must not have solid state devices necessary for operation) for those radios.  Transportation and communications are so dependant of the use of solid state equipment that in event of such an attack we would have our life line cut off and the organization I just described could be the saving force.  

It is a scary thought when you realize our very existence has become dependant on a very fragile silicone thread. With the right equipment  and organization we, ham radio operators, could become the safety line to catch our society incase someone should cut that thread with a nuclear weapon.

From 1896 when Guglielmo Marconi invented the wireless telegraph until 1901 when he added a tuned circuit to the receiver the radio receiver was just an antenna connected to a wire which went to a detector. After Marconi added a tuned circuit the receiver had a little selectivity. It was not until 1906 when Lee de Forest added the grid to the diode and the receiver was able to have something more then just passive devices. With the grid RF amplifiers could be added before the detector and audio amplifiers after the detector which was a great improvement.

The tuned radio frequency (TRF) radio became the receiver of choice. The problem was that each stage had to be tuned separately and the tubes had to have low amplification or they would oscillate. The TRF remained the only way to add amplifiers ahead of the detector until Edwin Armstrong conceived the idea of superhetrodyne during WW1.

In 1914 Edwin Armstrong, an amateur radio operator, patented the regenerative detector. This was a real break through in radio receiver progress.

The regenerative receiver uses a positive feedback which greatly improves both the sensitivity and the selectivity. In the earlier days the receiver had, compared to today’s receivers, a very large coil for the input tuned circuit which fed the grid. It had a coil of just a few loops of the wire in the plate circuit. The coil in the plate circuit, called a tickler coil, would be physically moved in the proximity of the input tuned circuit until the positive feedback was almost enough to cause oscillation when receiving an AM station and it was adjusted just into oscillation to receive a code station. The oscillation would produce a heterodyne, two signals mixed in a nonlinear circuit which result in an output of the sum and the difference of the two input frequencies, which could be heard as a tone this allowed true CW to be used. Up to then only MCW could be used.

The gain of a regenerative receiver using just one tube can be up to about 20,000 and if a MOSFET, not developed until many years later, is used a gain of 100,000 is possible.

Then in 1922 Mr. Armstrong patented the Super-Regenerative receiver. The super-regenerative detector uses a “quenching” frequency usually about 20 KHz to 30 KHz though other frequencies are also used. Using the quenching frequency to quench or stop the detector’s oscillation there is no need to adjust the tickler coil. This makes the receiver easier to operate and increases the sensitivity. Because they are inexpensive and easy to make these receivers are still being built and used, mostly in VHF and UHF ranges, today. (Note: Super-regenerative receivers do not work on 5 KHz deviation FM it just sounds like a carrier being received.)

One of the biggest disadvantage of the regenerative and the super-regenerative receivers is they radiate a lot of noise over a wide area of the frequency on which they are being used. Back in the Sixties Heath Kit had a little 10, 6, and 2 meter transmitter receiver kit called the Tenner, Sixer, and Twoer. These units used a super-regenerative receiver. In 1965 I had a twoer installed as a mobile. That was the year the United States Coast Guard transferred me from Brownsville, TX to Coast Guard Radio Station New Orleans (NMG). My wife and I were driving around Metery (just across the river from New Orleans) looking for a place to live. We had our infant daughter with us. The Metery Police at that time were using 150 MHz radios. As we were driving I saw a police car sitting on the side of the road. I was very careful to obey all laws as I passed him. I came to a full stop at the stop sign. And when I pulled out from the stop sign he followed me and shortly on came the blue lights (I had never seen blue lights before but I guessed they meant the same as the red ones) so I pulled over. He stopped right behind me and one officer got out of one side of the car and the other from the other. They approached the car with hands on their guns, though they were still holstered, and one grabbed my door with his free hand and the other grabbed my wife’s door. The questions started flying, who was I, why was I there, and finally what is that radio. It took years before I understood why they pulled me over. My Twoer opened up their squelch when I passed by and again when they came up behind me and they wanted to know why.

Just as a little added note. Erwin Armstrong invented the FM transmitter and receiver a few years after the super-regenerative receiver.

In the days of vacuum tubes gas filled tubes were used as voltage regulators and they were effective for the need of the time. A tube normally runs at a much higher voltage then a solid state device and a much lower current to perform the same operation. The voltage regulator tubes did not have a filament so they were called cold cathode tubes. One very common regulator tube was the 0A2. The 0A2 was connected in series with a current limiting resistor and the two shunted an unregulated voltage of at least 180 volts. The result was a 150 volt drop between the plate and the cathode of the tube. The cathode would normally run directly to chassis ground.

Solid state devices normally require a much lower voltage then the 150 volts of the 0A2 or even the 90 volts of the 0B3. One way of doing this where a relatively small current is required is by using a device called a zener diode. If you looked at the schematic diagram of the tube regulator and the zener diode regulator they look much the same; a current limiting resistor in series with the diode but this time the plus voltage is taped off the cathode side of the diode.

The reason the zener diode is reverse biased is because as a regulator it works on the principal of the zener effect also sometimes called avalanche point. There is a subtle difference between zener point and avalanche point but it is too involved to be described here. The zener voltage is that voltage where the depletion region, that is the junction between the P and the N portion of the diode, is breached and current starts to flow. In most diodes when this region is reached the reverse current destroys the diode but in the case of a zener diode it is designed to work in this region up to a certain limit. The size of the resistor that is place in series with the diode is easily calculated. A zener diode is rated in voltage at which it works or its zener point and the maximum wattage it can sustain without destruction.

To calculate lets say we have a 12 volt unregulated source and we want a 6.1 volt regulated source. I used 6.1 because that is a common voltage in which the zener diode comes and it is close enough to 6 volt that it can be used in a most 6 volt application and for sake of simplicity I am going to use 12 volts and 6 volts as my two levels. The diode we will be using will be 1 watt. We know the voltage drop across the diode and the resistor will be 6 volts each. With the diode’s maximum power level being 1 watt and the current through the resistor being equal to the current through the diode plus the current through the load so the resistor should be rated over 1 watt. The maximum current that can flow through the diode is .167 amps (W/E=I) 1/6=.166666 which rounds up to .167. If the regulated voltage is being used to supply power for an oscillator which switched off and on for CW operation that draws .06 amps in key down and 0 amps in key up positions the resistor will have to be large enough to dissipate the key down power without allowing excess current through the diode in key up.

A good engineering practice is to run a device at about half of its maximum rating. Using this factor the maximum current that can pass through the diode is .0833 (Max. current = .167 amps times .5 equals .0833 amps). That means the resistor’s resistance can not less then 72 ohms (6V/.0833A=72.03 ohms). The voltage drop across both the diode and the resistor has to continue to be 6 volts so the current through the resistor must remain the same during both key up and key down. The current will have to be split between the load, the oscillator, and the diode which means the current through the diode will decrease by the amount of the load. The current through the resistor remains at .0833 amps when the .06 amp load is operating so the current through the diode will equal the total current through the resistor, .0833 amps, minus the current passing through the load, .06 amps thus when the oscillator is operating the current through the diode is .0233 amps (.0833 - .06 = .0233). This means the diode acts like a variable resistor so the total current through the resistor remains constant. When the load is on the diode increases its resistance and when the load is off the diode decreases its resistance so the voltage remains constant.

That was all easy but if the unregulated voltage is a vehicle battery then the voltage swings between 12 and 14.8 volts. To calculate this the extremes must be taken into consideration.

The voltage drop across the current limiting resistor this time will very because the voltage across the diode will remain at 6 volts When the unregulated voltage is 14.8 volts the drop across the resistor will be 8.8 volts. To limit the current to .0833 the resistor must be 106 ohm (8.8/.0833=105.642). When the unregulated voltage is at 12 volt the current trough the resistor will drop to .0566 amps which is insufficient to cover the necessary current of .06 amps necessary to run the oscillator. In this instant the maximum power rating of the zener diode can be raised this will allow the resistance of the current limiting resistor to be dropped sufficiently to provide the current necessary for the oscillator and regulator to operate.

There is another way to provide sufficient current even if the load requires well above the .06 amps but this requires some extra circuitry. It is done by controlling the output of a pass transistor with a Voltage Error Amplifier that compares the diode’s voltage drop and the pass transistor’s output voltage. By doing this the voltage drop across the zener diode and the voltage drop at the output of the pass transistor will remain the same.

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Still cleaning up storm damage.

Though prepared for emergency operations it was reported tonight that this district of ARES had no calls for emergences.

When introducing the diode as a subject most people with a little electronic knowledge will just say, “ho hum what can be said interesting about the diode?”

Actually books can and have been written about the diodes, large books. A simple definition the diode is an electronic device which allows electrons to flow in one direction with much less resistance then in the other. It could be called an electron check valve. A check valve is a valve which allows fluid to flow in one direction but will not allow it to flow back. The valves in our heart are check valves. That is why some countries refer to what we in the United States of America call a vacuum tube as a valve.

When speaking of the diode Thomas Edison’s is usually credited with its discovery in 1880 which he patented in 1883 but the real discovery of the diode goes back further. Edison only rediscovered thermionic diodes. The thermionic diode effect was found by Frederick Guthrie in 1873 but Guthrie was not credited with the fine because he did not patent it and Edison did.

Then the normal thinking is that the semiconductor diode came many years later but the year after Guthrie found the thermionic diode Karl Ferdinand Braun discovered the crystal diode effect which was used by early crystal radios. That little “cat’s whisker” crystal detector used in those early radios was a solid state diode. The “crystal” was usually made of galena, a naturally occurring sulfide ore of lead, thus it was a natural semiconductor. A small metal wire called a “cats whicker” was moved around the surface of the crystal, which was mounted in a metal container, until a sensitive point was found. That sensitive point was nothing more then a naturally occurring PN junction. If you hold up a clear glass solid-state diode today you can see that a cat’s whisker is still used in the diode.

The diode has many uses in electronics. They are used as rectifiers, modulators and demodulators, amplifiers, oscillators, capacitors and regulators to name a few. A magnetron, the heart of a microwave oven, is a diode.

Come back next tomorrow as we will look at the tunnel diode, a truly fascinating device.

The vacuum tubes were finally becoming available for amateur use in about 1920. These tubes were low powered and designed for receiver use. The first real power tubes, UV-202 and UV-203, suitable for transmitters were placed on the market in March 1921.

With the advent of the UV-202, UV-203, and the UV-204, which came out just a month or so later, amateurs could earnestly start changing over from Spark Gap transmitters to true CW transmitters. Even though the true CW transmitters were possible in the early 1920’s it was not until 1927 that the International Radio Consultative Committee (CCIR which at that time was part of ITU) decreed that spark gap transmitters would be phased out and this was to be completed by 1939.

Receiver normally used batteries for power in those days but it was impractical to try to run the transmitters on batteries and in 1921 suitable rectifiers tubes were not available so the transmitter tubes were fed with raw AC. The transmitters usually consisted on one tube acting as the oscillator and final all in one. They were normally not crystal controlled though W.G. Cady published his findings on quartz crystals and frequency stability in 1920. A common design was to use two tubes in a basic push pull fashion so while one tube plate was going positive and conducting the other was going negative.

These new transmitters had drift, chirps, clicks, and pure AC hum. What a sound that must have been!

The solution to the problem was the electrolytic rectifier. These were apparently commercially available but most hams made their own. All it required was pint jar, an aluminum bar, a lead bar and a solution of sodium tetraborate, more commonly known as Borax, or baking soda in water. The top portion of the jar was usually coated with paraffin to prevent a deposit buildup on the side of the container. The aluminum electrode form a layer of corrosion and thus becomes the cathode while the lead, it has been found that almost any metal except aluminum will work, is the anode. Usually several jars were placed in series to rectify the high voltage needed for the transmitters.

Those transition days from spark gap to vacuum tube transmitters must have been some really fun days in amateur radio.

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.