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