TRANSMITTERS OF DAYS GONE BY

 

Viking Ranger on the top right and SX-100 on bottom left.

Viking Ranger on the top right and SX-100 on bottom left.

I miss the vacuum tube. Oh I am not saying the vacuum tube equipment better then modern solid state equipment. If I believed that then I would have to clean out my shack and replace most of my equipment.

Vacuum tubes just had something that solid state does not have besides a lot of extra heat. I can’t explain it but maybe it is just an old man remembering where he came from.

6146

6146

When one looks at the price people want for vacuum tube equipment on Ebay it would appear that there are several people who still have an interest in them.

With so many transmitters today the operator can just set it on frequency and, if the antenna is resonate, start transmitting. No adjustment is necessary. That was not so with vacuum tube transmitters especially those with class C amplifiers. The class AB and class A amplifiers used with SSB transmitters were usually not quite as complicated.

When the operator of a vacuum tube transmitter changed frequency first it was necessary to first check the final place current and Elmac AF-67 transmitteradjusted the plate capacitor for a dip to minimum plate current. Then the grid capacitor and driver controls were adjusted for a peak in plate current and the final amplifier capacitor was again adjusted for a maximum dip in plate current. The plate load capacitor had to be adjusted so the plate current was maximum while the plate capacitor was readjusted for minimum plate current and the grid capacitor was set for maximum current. (Thus the term, “dip the plate and peak the grid.”) The drive was adjusted so the final plate voltage times the plate current equaled desired transmitter power.

It was very important that the operator properly adjusted the transmitter because improper adjustments could result in reducing the life of the final amplifier tube and other components. It could also result in superiors and/or harmonic radiation.

I remember one transmitter we had to learn how to adjust in Coast Guard Radio School that did not have a final amplifier plate current meter. There was, instead, a window that allowed the operator to see the final amplifier’s plate. When the transmitter was operated the plate would glow a cherry red and that meant it was operating at the proper current level. The place capacitor was adjusted for minimum brightness and the grid capacitor was adjusted for maximum brightness.

If you become the proud owner of a vacuum tube transmitter, before you put it on the air, find someone with experience to show you how to load it or if you have the manual carefully read the operating instructions and follow them to the tee.

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FLYBACK DIODE USED ON RELAY CIRCUITS

Typical Electromagnetic Relay

Typical Electromagnetic Relay

The chatter of a relay is not often heard in the modern ham radio, but when I first got my amateur radio license there would most likely be more then one relay circuit somewhere in the shack. Today, most of the time, solid state circuitry is used rather then the bulky electromechanical relay or electromagnetic relay for switching circuits off and on.
The relay is a rather simple device. It has an electromagnet winding that attracts an iron armature when it is energized. The armature is connected to an electrical switch contact that will move when the armature moves. The movement will either bring the contact in contact with another switch contact thus completing the circuit or it will move the contact away from a contact it is touching while the coil is not energized thus opening a normally closed circuit; it is also possible that the contact can be moved off one contact (normally closed) and connected to another (normally open). The armature might move one contact or more.

Relays are not completely relegated to history though most of the time when modern hams come in contact with them it is when they are using older equipment. One place you might want to use a relay is if you want your mobile radio to automatically shut off when you turn off the ignition. This can easily be done by using a power relay that is energized by taping its coil into a circuit that is turned off and on by the vehicle’s ignition and switch the 12 VDC through a normally open contact on the relay. Power for a mobile radio should always come directly from the vehicle’s battery and not be connected a wire inside the cockpit.

Vacuum tubes are high voltage devices thus they can be very forgiving to voltages that will destroy solid state equipment. When we hooked relays up in or associated with tube radios we normally did not have to be concerned with voltage spikes caused by the collapsing magnetic fields into the coil but with solid state equipment that is a whole different story.

When the electromagnet is energized it builds up a magnetic field around it. If the coil is energized by Direct Current (DC) then when the circuit is opened that magnetic field will collapse back into the coil thus creating a very high reverse voltage. A 12 volt relay coil can generate over 200 volts reverse voltage. This voltage can destroy solid state devices.

This effect is known as “flyback”. Flyback is used to generate the voltage needed to operate the spark plugs in a gasoline engine. It is also used in the flyback transformer in a TV set to generate the voltage needed to operate the CRT.

To prevent flyback voltage from causing damage a diode called a “diode snubber,” “flyback diode,” or “free wheel diode” is placed SCHMETIC DIODE ON RELAYacross the coil in reverse polarity to energizing voltage.

When voltage is applied to the relay the diode snubber serves no purpose.  It is reverse biased so an insignificant amount of current passes through it. But when the relay is de-energized the resulting flyback voltage will be a forward biasing voltage which the diode will short out thus protecting any components that might be damaged by the high voltage.

A sine wave alternating current (AC) has constant smooth rise and fall of voltage so a strong magnetic field does not form thus a flyback diode is not only unable to be used but is not needed.

Square wave AC voltage should not be used on relays because of the sudden rise and sudden reverse in voltage will cause voltage spikes.

 

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VALUE OF KNOWING CW

If you have been reading this blog you surly know how much I believe in CW. When the CW requirement to get a ham license was removed I really thought it was a mistake. Looking back on what has happened sense the change I have changed my mind. When those who wanted to get their Amateur license operators were forced to learn CW to get their license they did not want to use it once they passed the test. Now hams are learning CW because they want to and listening to the ham bands I really believe more hams are using Morse code today then before.

There are still some hams who do not want to learn Morse code and that’s fine but when I hear them say there is no value to CW today then my feathers get ruffled.

Today I experienced a situation where the value of knowing CW was evidenced.

The 40 meter conditions were not great this morning when the California Rescue Communications Net was on. Some stations were having difficulty checking in and needed to be relayed to check into the net. While trying to hear stations through the foreign broadcast noise and QRN I heard a CW station and was able to copy his call and relay him into the net.

The station was apparently not able to be heard using LSB but he was able to be heard using CW. If there had not been an operator in the net who was able to copy CW then his signal would have fallen on deaf ears.

Okay, you might say, it is just a daily net and it is no big deal if a station is unable to check in just one day. I would agree with that but this is an emergency operation net and what if this had been a real emergency operation? That would change the value of each station wanting to be heard.  Is it not possible that there could have been other station operators that did not know CW who could have checked in if they had known CW?

I am a firm subscriber to the motto of ZUT (An organization composed of former Coast Guard Radiomen), “CW Forever.” (http://w5cgc.org/)

Key actually used on Coast Guard Cutter McLane

Key actually used on Coast Guard Cutter McLane

 

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Hallicrafters And Ham Radio Operators Help Win The War

During World War 2 ham radio operations were suspended in the United States but ham radio operators were able to utilize their skills to help in the war efforts. This video shows how Hallicrafters and ham radio operators work together to provide a vital piece of communications equipment for the war efforts.

You might also find it interesting to compare the compact mobile radio of that era to the mobile radio of today.

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Veterans Day Special Event Station

K9TAL
     On Veterans Day, Tuesday, November 11, 2014 TALARC (The American Legion Amateur Radio Club) will be operating a Special Event Station to honor veterans of the United States Armed Forces  using the one by one special event FCC-issued call sign of W9L. The station will be on the air from 0900 to 1600 EST. 
   To contact the special event station Ham radio operators should tune to 20 meters – 14.275 MHz USB, +/- 5 KHz, or IRLP Node 4816.  Central Indiana can use to 146.46 MHz simplex or to the 145.17 MHz repeater in Hamilton County, Indiana to make contact.  Stations working W9L can send a 9X12 inch self-addressed-stamped-envelope to The American Legion Amateur Radio Club, 700 N. Pennsylvania Street, Indianapolis, IN 46204, and TALARC will provide confirmation on your contact with a Veterans Day Special Event certificate.
   See the story on the Legion website:
 
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When Setting Up An Emergency Station Respect Other People’s Property

There are some who may read this post and wonder if it is necessary for me to say these things. After observing humans for over 65 years and seeing how they treat other people’s property I say yes it is necessary. Most of the disrespect for other people’s property, I believe, comes from a lack of training so it is my purpose to give just a little training.

When you set  up an emergency ham radio station it will most likely be on property you don’t own; in other words you will be a guest who been allowed this privilege. Respect that property whether it is a building, an open field, or whatever is provided. It, most likely, is a place where someone else lives, works, or plays. When you return it to them they would like for it to be returned to them just like you found it when you got there.

Before rearranging furniture, equipment, or any thing else take time to look and write down how these items are arranged and where they are located. Again I say write it down and draw a diagram because, if your memory is anything like mine you may forget just how it was; also there is the possibility that someone else may have to break down the station and set things back in order when the emergency is over.

Leave gates the way you found them. By that I mean if you enter through a gate and it was closed before you entered it stop and take the time to close it. You may not see any reason why a gate should be shut but if the owner has shut it then it should be shut even if you are not going to be there very long (animals can escape very quickly even if you don’t see them.) You don’t have to know why. If the gate was open then don’t take it upon yourself to shut the gate.

For the most part the same thing can be said about doors in a building.

Keep your vehicle on the road or designated area for vehicle. Even if you think it will be okay to drive there, if you have not been given specific instruction to drive there, don’t drive there.

Do not litter. If you brought it in then remove it. If someone else brought it in for you to use then make sure, if you are not able to remove it, that someone is responsible to remove it and follow up to see that it has been removed. Except maybe under some conditions, do not use their trash cans. Take your trash off the property.

Do not duct tape antennas to the wall. Duct tape will sometimes cause paint to chip when it is removed. Do not put nails or staples in anything.

Amateur radio stations need antennas.

If you erect an antenna in trees be sure you do not damage the trees or any fruit that may be on them. In like manner treat any structure you may use for erecting an antenna or installing equipment with respect.

If you do cause any damage inter the information in your log book and notify your leader and the owner if you are able to.

 

Many times people feel like it is no big deal. They would not be bothered if someone else did that to them but the owner or manager of the property may not have the same standards as you have.

Showing respect can get an invitation to use that property again if needed in the future but a lack of respect can result in a big wall being put up against any future use.

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Encourage Young People into Ham Radio

Girls with antennaAmateur radio still servers an important function in our society. When old timers like me go silent key it is the younger generation that will keep it going. Encourage young people into ham radio and encourage them to be active.

(Photo from QRZ Now – Ham Radio Facebook page)

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Does Your Antenna Work?

The best antenna you can afford that will fit on the real-estate you have is important but it also important that you not exceed what you can afford and lets face it you can’t put ten tons of fertilizer in a one ton truck.

My first antenna was a center fed 40 meter dipole feed with 300 ohm twin lead. The transmitter was a Viking Ranger which, as anyone who ever owned one can tell you, will load just about anything.

Being a novice I could work the 80, 40, and 15 bands and they all worked using that one antenna. I was happy with it and worked a lot of stations but older hams told me that I couldn’t do that. I had to use 50 ohm coax cable to feed that antenna so I took down the twin lead and put up coax. The Ranger would still load all three bands but 80 meters did not work well at all while 40 and 15 meters showed no improvement that I could see.

Later I purchased a 23 foot vertical antenna that had a big coil at the base. By using an alligator clip the inductance of the coil could be changed thus allowing the antenna to be used from 160 to 10 meters. I could not put down radials but I made a lot of contacts on that antenna.

It is true that to operate most efficiently a vertical antenna needs a good ground plain. This means having a sheet of metal or metal radials at least one quarter wave long running out from the base of the antenna in all directions from the antenna.

A ground plain for UHF and VHF  is fairly easy to make but when it comes to making a ground plain for a vertical HF antenna it can become a lot more complicated because of the size of real-estate that is needed. To ground mount a 20 meter vertical antenna for optimal performance a ground plain of just over 33 feet in diameter needs to be laid down. That would be a tight fit for most city lots even if you had nothing else in your back yard.

There are vertical HF antennas available today that can be put up a few feet above The ground with no radials and I am told they work quite well. Having never experienced them personally but having very reliable recommendations I would say if you can afford
one this would be the best way to provide an omni-directional vertically polarized amateur radio station.

If you can not afford a no ground plain required vertical HF antenna but you do have access to or can build an antenna that would best be operated with a ground plain but you do not have room for such a ground plain the soil should provide sufficient ground plain allow reasonable operation. Not optimal but reasonable.

In the late 1960’s I lived in Sacramento and used a Hy-Gain 18AVQ which is a 80 through 10 meter vertical antenna. It should have had a metal ground plain but there was not enough room to put one in for the antenna. Using that antenna on a 180 watt PEP input (approximately 90 watt PEP output) transceiver I was able to work many DX stations including Europe, South America, Japan, Australia, and more. I was also able to run weekly phone patches for a missionary in Liberia to his family living locally.

The point is, when it comes to setting up a ham radio station, part of the fun is to evaluate your resources and make the most effective operating station you can. Be sure you are not radiating any unwanted signals. Then have fun. I am sure it will work better then you might think it will.

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Phony Phone Numbers

If you are like me you hate harassing phone calls from telemarketers. They call and take you away from what you are doing but you try to be nice and tell them you are not interested. Then within a day or two they call again and then again.

Such misuse of  the telephone has caused many people, when asked for their phone number, to give a false number. Sometimes they are real numbers just not the number of the person giving out that number. The result of that is someone else gets the call.

You may be wondering what this has to do with ham radio.

When taking a test for ham radio you are asked for your phone number. It is estimated that over half maybe as high as three quarters of the numbers given are incorrect numbers.

These numbers are used by the ARRL to send a message of congratulations to those who successfully pass the test. It is not necessary to enter any number so if you do not want to receive the message of congratulations from the ARRL just leave that space blank. It is just common courtesy.

 

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The Sacramento Valley ARES Website

As any regular reader of this blog knows, I firmly believe using ham radio during an emergency situation is of great importance in to the well being of our communities. Cell phones, land line telephone, and internet are very effective means of communication most of the time, but these all have a complex infrastructure and if that infrastructure fails, as it is very apt to do during an emergency, these means of communications become useless. Ham radio does not have an infrastructure so as long as some means of emergency power is available (sun, wind, water, hand cranked generator, etc) communications is possible. Many times in the past ham radio has been the only means of communications in and out of stricken areas, and without doubt it again will be many times in the future.

 

The ARRL sponsored ARES (Amateur Radio Emergency Services) provides a means whereby ham radio operators can facilitate a higher level of preparedness for themselves and their station. ARES provides training, information, and organization for emergency operation.

 

In the spirit of amateur radio emergency preparedness the Sacramento Valley ARES has put together a website which, though most specifically aimed at Sacramento Valley, will help any ham radio operator or group of hams to be more prepared. This includes ARES membership information, training resources, information on local nets, links to a variety of other related sites, and much more.

 

This  site can be found at: http://www.sacvalleyares.org

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