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WESTLAKES
Amateur Radio Club Inc.

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The Westlakes Weekly Broadcast.

The Westlakes news broadcast is transmitted 
every Sunday at 9am on 2 meters at 146.900 MHz
(the Hunter Radio Group's Repeater)

 

 

WARC News   8-12-2019

WARC Broadcast 8th December 2019

It was a fine day at the club yesterday, with the temperature being somewhat bearable to withstand a session of required discussions on the seat of knowledge. The Meeting Room lost its popularity as the air conditioner decided to stop working. A quick run around the joint by someone revealed the existence of a couple of fans which were quickly placed to dispel some of the heat.
Another job for Maurie VK2CD no doubt. Also it was good to see Al VK2OK up from Sydney for his regular visit.

Our amateur students were out in force for their regular catch-up in the Class Room.

The activities Room was that busy, that all we were advised about the goings on, was that it was secret men’s business. At one stage Barrie QG was seen doing his impersonation of destroying a desk microphone.

At approximately 1300hrs, the Meeting Room suddenly filled up in anticipation for the second part of the presentation on D.M.R. given by John VK2DLP, and while it is sure he gained some more conversions to the faith, there are some amongst us that are still H.F. diehards. Regardless of our various convictions, the presentation was very well received and was rounded off at the end with a myriad of questions. While it is a comparatively new technology, different and in some respects intriguing, it has certainly got people talking and in some cases following through on this new found interest. I guess that’s why we call us, The Amateur.

During the afternoon Aly VK2AFZ fronted up with another donation to the coffers. Well it is a donation by all of those who have remembered that they needed a thingamabob for their dooverlackie, to get it working. By remembering that we do have a store, that sells whatsits for this, that and the other. We are all donating to the Club – our club!

Now we will go onto Part Two of our oscillator story.

Last week we introduced the oscillator. How important the oscillator is to daily life and, particularly to us as participants in the hobby of amateur radio. The VFO, the BFO, Armstrong, Clapp, Colpits, Hartley, and more, all essential to us in our beloved hobby. We learned last week of the humble beginnings of the oscillator. From a crude spark excited circuit with some inductance and capacitance to limit the oscillation to a broad range of frequencies, to the sophisticated (for its time) vacuum valve triode oscillator.

We started our current discussion with L and then C and then by combining the two, we ended up with the tuned circuit. The tuned circuit really is a natural oscillator - without resistance and losses, an LC tuned circuit will oscillate indefinitely once excited. As we live in a real world though, the presence of resistance and other losses leads to damping of the oscillation which eventually dies out. The time it takes for the oscillations to die out is determined by the time constants of the circuitry.

Oscillators are found throughout nature - Eric Landburg from the Technical University of Denmark claims that ‘oscillators are a basic principle in nature’. But all oscillators are damped unless excited by some form of external energy. A pendulum, for example, one of nature’s basic natural oscillators, will eventually slow and stop, unless it receives an input of energy from, say, the potential energy in a pendulum clock weight.

So how do we keep the oscillation going that we need for our VFOs, mixers, etc? The electronic oscillator needs a number of basic design considerations to maintain stable oscillation. It is basically an amplifier with positive feedback. In order to overcome the losses discussed above we need to provide voltage amplification and positive overall gain. The overall gain of the amplifier needs to be greater than one (unity). Oscillations can be maintained by feeding back some of the output voltage to the tuned circuit that is of the correct amplitude and in-phase (i.e. positive feedback). The phase shift of the feedback circuit must be zero or 360 degrees so that the output signal from the feedback circuit is in-phase with the input signal. We also need a stable power supply and components with stable temperature and frequency characteristics or use a buffer amplifier to isolate the oscillator from the load to ensure amplitude and frequency stability.

So, although a serendipitous find in the early twentieth century, we now know how to design a stable electronic oscillator for any function.

That’s the end of the story of the oscillator.

Now for an interesting diversion.

How many of us have been accused of talking in lower case? Well we could mention names here but you all know who you are. If some of you were listening to the Ezybee Net yesterday morning, reference would have been heard of - talking in lower case.

But, does anyone know where the term came from?

Next time you venture into the land of the “Long White Cloud”, (that’s that country over the other side of that puddle of water east of us) take a visit to Russell, in the Bay of Islands and find your way to Pompallier House. Representatives of the local Ngapuhi Tribe will take you on a guided tour. The house once served as the headquarters of the French Catholic Mission to the Western Pacific. On this tour you will be shown the 19th century Gaveaux Printing Press. You will see boxes of type set lettering in order from left to right.

Capital letters across the top and small lettering across the bottom. The boxes (made of timber) were also known as cases. Capitals in the upper cases and small letters in the lower cases. There we have it pure and simple.

Now to Coming Events

Saturday 14th December - December Meeting Day
Saturday 14th December - The Annual Westlakes Xmas Ham Raffle – drawn at the conclusion of the General Meeting. So come to the next meeting and support your club.
 

    

 

 

 


Westlakes Amateur Radio Club Inc. York Street, Teralba NSW