Hi all
This is the July Anode for 2013 in html format.
If you know of a new member, please forward this link to them.
Ask them to email me with their details (name etc.), and I will add them to
the email list.
73
John Brock
(formerly ZS6BZF, now ZS6WL)
NOTICE - This message contains privileged and non-confidential information
intended for the use of Radio Amateurs. If you are not the intended
recipient of this message, you are notified that you may disseminate, copy
and take action based upon the information contained therein. If you
received this message in error, please read it, maybe it will entice you to
try Amateur Radio as a rewarding hobby.
ZS6WR page: http://www.zs6wr.co.za
----> more
This is the July Anode for 2013 in html format.
If you know of a new member, please forward this link to them.
Ask them to email me with their details (name etc.), and I will add them to
the email list.
73
John Brock
(formerly ZS6BZF, now ZS6WL)
NOTICE - This message contains privileged and non-confidential information
intended for the use of Radio Amateurs. If you are not the intended
recipient of this message, you are notified that you may disseminate, copy
and take action based upon the information contained therein. If you
received this message in error, please read it, maybe it will entice you to
try Amateur Radio as a rewarding hobby.
ZS6WR page: http://www.zs6wr.co.za
----> more
Volume
14,
Issue 1
THE
WEST RAND AMATEUR RADIO CLUB
Inside
this issue:
|
|
Editor’s
Comments
|
1
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3
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6
|
Editor’s
Comments
Like
it or not, the Anode has to change with the times. As a hobby,
Amateur Radio is changing rapidly as technology changes. We should
try and keep up.
When
I started the new Anode in 2000, I did not think the format would
change from the long standing one. But it did. Once upon a time this
was typed on a typewriter and 'Roneo-ed' off to be mailed to members
monthly.
Later
it was typed on a typewriter and then photocopied on a Xerox
machine. And then mailed by the Postal service to members.
The
cost of mailing was not onerous as many people used it. So the costs
were spread over many 'clients'.
With
the advent of email, things started to change quite rapidly. Printed
copies were replaced by Portable Document Format (PDF) files. When I
started sending the Anode out, I kept the file size to below 0.5MB.
As most members were still on 'Dial up'.
Also
in those 'early days', I used a desktop publishing software package
called Microsoft Publisher. It came with my copy of Microsoft Office
2000 Professional. This laid out the Anode in a nice format and
outputted the file in Postscript format.
Postscript
is what the lasers use to set up pages before throwing carbon
granules at the paper. It is the base of a PDF. So a quick
transformation to PDF was done by GhostScript/GhostView. This last
piece of software was 'Open Source' and free.
When
my office applications started to crash for no apparent reason. The
help would send you to the Microsoft Office upgrade site, to get you
to buy the latest version. I turned to using the Open Office
package. But this did not have a 'Publisher'. It did however have an
export to PDF function. I carried on using Microsoft Publisher.
I
tried out new layouts on various members. I got no reaction. Finally
I got some positive feedback for a new format that I had laid out in
the Open Office word processor.
With
this 'new and improved' format came some nice features. The
'clickable links'
allow the reader to jump to articles and web sites. [That one takes
you to the club's web site.]
I
believe the time has come to change the Anode's format once again to
a multi-contributor blog. Having more than one 'contributor' will
mean fresh articles and news. No longer will the members wait for a
whole month for the latest articles and news.
Amateur
Radio is progressing at an ever increasing rate. It is no longer
'wireless' nor Heathkit construction projects. There are still
unexplained and untried areas. One of which is the compact H.F.
Aerial for use in cluster housing areas.
Recent
events in Amateur Radio have shown me that the latest and most
exciting developments are in the use of technology available right
now. Software Defined Radios (SDR) are being released at an ever
increasing rate. Use of small micro systems such as the Raspberry Pi
for various functions are appearing on the web sites daily.
In
South Africa, we have an 'issue' with high technology and electronic
components. We remain a small market with very few friendly
manufacturers. When a chip gets used overseas for a new and low cost
SDR, we will not see that chip here until it is used in a mass
produced box.
A
recent example is the Realtek
RTL2832U which
is
available overseas for $20 (R200). This chip can do the SDR function
from 54MHz to nearly 2GHz. It even has a USB2 interface! So you can
plug it into your tablet and listen to the Sunday bulletin on 2
metres narrowband FM.
[for
example] A $40 Software-Defined Radio
The
Club is now going into a new year with a new committee. In the
Northern Hemisphere, Winter is the time for new projects. I have an
H.F. And VHF/UHF Aerial system to make. Recent events have made it
impossible to give more time to the Club. So I need some
assistants...
{---}
Digital
Modes Talk
Noel
Hammond ZR6DX, gave an interesting and well presented talk on
Digital Modes in amateur radio at the West Rand Club House. Noel
spoke on everything from the beginning of digital modes, their
inception and progression, right up to their use in modern day
amateur radio. The main object of this talk was to introduce fellow
hams to the digital modes world, using Ham Radio Deluxe's digital
modes software called DM 780 (Digital Master). We were guided
through everything from the initial setup, basic operations, use of
macros and most of the important functions one would generally us.
The different digital modes used, as well as band width per mode,
the speeds of each and their general usage throughout the HF bands
were explained. The main focus was PSK31 and RTTY as these seem to
be the most popular modes in use today, however there are many to
choose from.
Noel
also delved into the setup of the logbook functions in HRD and the
syncing of this logbook with online sites such as qrz.com and
lotw.com (Logbook Of The World). Noel demonstrated how each copy or
backup of a logbook is made and the advantages of using the online
resources to streamline your digital logbook and make sending and
receiving of operator/station data while using Digital Master or HRD
simple and effective.
The
basic setup required to connect a radio to your pc using CAT and
sound card interfaces was also explained during the talk. Noel
described how these can be purchased locally or online, and that a
home brew version is simple and cost effective to build. Phillip
ZS6PVT was on hand with home made interfaces which he made available
to those present.
Along
with the talk we were provided with a CD containing all the software
needed. Also included were PDF documents which included everything
from schematics to course notes. A detailed 50 page booklet was
handed out which followed along with Noels Power Point presentation
for easy reference.
At
the end of the day, an HF station was setup and PSK31 was
demonstrated live. Those who stayed were given the opportunity to
make a few digital contacts.
Overall
the talk seemed to inspire all those present, and the response was
extremely positive. Noel should be commended for the amount of work
he put in to presenting an informative and easy to understand talk
on Digital Modes and HRD. At the end we were all more knowledgeable
in the use and operation of digital modes.
Here
is what a fellow attendee had to say on his blog regarding Noels
talk.
Noel
plans to hold another digital talk in the future due to popularity
and interest in this one. Keep your eyes and ears open for more
info.
Rory
ZS6RBJ
EH
Aerials
In
message <kt5ls2$13m$1@dont-email.me>, KaFKaesque
<kafkaesque@g4kfk.co.uk>
writes
>
[quoted text muted]
I've
commented on this before.
I
made an EH antenna for 14Megs to a variant of the W0KPH design.
It's a similar concept to the CFA.
www.b-howie.demon.co.uk/EH_14MHz.JPG
.It's about 40cm long .
It
looks a bit foosty as it was outside for about 6 months.
The
way it works is that a 1/2 wave dipole generates the H component
from the high current in the middle and the E component from the
high
voltage
at the ends . The length of the dipole gets the 90degree phase
shift. The EH antenna does this by moving the ends of the antenna
closer together by a combination of capacitance and inductance
loading. It's not fundamentally wrong, it's just not as efficient
as a resonant dipole.
It
radiated and received OK and didn't get hot even with 200W going
into it. I managed to work a few people on it.
I've
got some aluminium beer cans and was thinking of making one for
10MHz to use on WSPR.
I
don't think I'd spend good money on any of the commercial ones.
Anyone
else tried one ?
Brian
GM4DIJ
--
Brian
Howie
{---}
So I made a phase
detector – Automatic Aerial Tuning
Geoff
said that the original QST article was too technical and it used
valves. It predates the 73 Magazine article, which I put into the
Anode some years ago. [January 2002 Anode – the Tennamatic]
I
did a search (on Google) for “Phase Detector”. I got
very little in the way of circuit examples or explanations.
Why
use a phase detector, instead of an S.W.R. Meter?
Going
back to basic principles, you need to find the 'resonant frequency'
of your aerial system. If it were a simple tuned circuit, at the
resonant frequency, the reactances are cancelled out. The circuit
becomes resistive as L and C resonate. The resistance won't be
exactly what you want of course. It will need matching to the
feedline. Also thanks to Murphy's Law, the resonant frequency won't
be in the Amateur Band. This is why you use an aerial tuner.
Basic
Circuit (above)
The
diodes are OA91 or similar germanium diodes. Suitable for QRP work
up to 10 Watts or so.
Circuit
Explanation
The
transformer is a current sensing transformer. The load voltage
portion is used to switch on and off the diodes. This switched or
chopped current waveform gives an output voltage that reaches a
maximum at + and – 90 degrees phase. When the current and
voltage are in phase or anti-phase (180 degrees) the output will
approach zero.
This
'simple' circuit was fed from a signal generator at 0dBm to +10dBm
and the frequency set to 7.000 MHz. With a 51 Ohm resistor as a
'load', it gave a reading on the DVM [Digital VoltMeter] of a few
millivolts. Connecting a 220 pF capacitor across the 'load' gave a
larger reading. As did an inductance of 2.5 uH connected across the
'load'. The readings were small but of opposite polarity. I found
that as the signal generator was just about turning the diodes on,
the voltage feed needed to be an 820 Ohm resistor and the other
resistor an open circuit. Infinity Ohms – badly drawn on the
sketch.
Here
is what it looks like as a 'prototype':
Yes,
I could have put more turns on to the toroid to build up the
inductance. But I was aiming for a 'test circuit' to prove the
circuit. It works and is really only suitable for QRP operation and
shows the basic circuit in operation.
The
circuit needs to be made more 'sensitive' to the zero / 180 phase
shift point. So I am going to develop the circuit further. I will
let you know what I find.
Now
for the transistor version... JB 2013
{---}
Established
in 1948
KG33XU
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Phone:
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Email:
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HF
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