Amateurs In Court
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Spot The Loony
Barmy Barry G0GGV
New Phonetic Alphabet
History Of Swearing
Ray Withers G4KZH
What is a repeater, well we all know but it
is obvious that many people are unaware of what a repeater is and
what it does.
Basically, it is a receiver and transmitter
usually mounted at an elevated position, to enable communication
over a greater area than simply station to station.
ALL repeaters in the UK are privately owned
and funded and are freely available for anyone to use, despite what
some of the "repeater groups" think.
Basically, this is a 'Vanity' device,
rather like a personalised number plate on a car, it is a way to
pretentiously try and elevate oneself above the rank and file radio
amateurs by constructing a repeater and ostentatiously believing it
is yours and gracefully, or in some cases belligerently, letting
others use it.
What happens is that the equipment is set
up to receive transmissions on one frequency and retransmit them,
usually from a more advantageous position, on another different
frequency, whether the originating station wants it done or not.
A license from OFCOM is required. There are
several downsides to repeaters, the license holder becomes
responsible for the re-transmitted signal. This is of little
consequence now as since December 1st 2008 the rules dramatically
changed, but in the past, music and swearing etc. were considered illegal.
What usually happens is a group get
together and buy or build the required equipment, find a suitable
place to mount it, and get the necessary permission from the
property owners, plus get a supply of mains power, and these days,
an Internet connection, to run it.
A repeater is a fully automatic device that
when it receives a signal on one frequency, will automatically
re-transmit it on another. In the past, repeaters were activated by
sending a 1750KHz tone, a few still respond to this, but nowadays it
is more common to use
CTCSS tones that seamlessly
activate the repeater when you wish to use it. A CTCSS tone is
sub-audible and generated by your transmitting radio, each repeater
uses a different tone for activation.
illustration should give an idea as to the basic idea of repeater
As most 2 Metre and 70 Cm radios are fairly
limited in range, repeaters are found at almost 30 - 40 mile
intervals. So called "Short Wave Listeners" monitor repeaters as do
the majority of active radio amateurs, standard practice is to call
for a contact on the repeater, then go and find a free frequency,
although there is no reason not to continue on the repeater if it
takes your fancy.
As you can imagine, repeaters are where the
fun is and have long been abused with all manner of automatic
devices and just simple mucking about and playing music. On a repeater you have the
biggest audience, so naturally that is the place to play.
Repeater abuse has been tackled many
different ways over the past 50 years, all with little effect,
changes in legislation now mean that the "Repeater Keeper" (the
licensee of the station) is responsible for anything his station
(the repeater) re-transmits, and many people have installed remote
switch off facilities. It can be endless fun forcing the keeper to
switch it off, waiting for it to come back to life again, then
making them switch it off again.
R.I.D. Repeater Improvement
Chinese walkie talkies or handhelds can be found on eBay for as low as
£10.00, Baofeng being the most common, these are an ideal basis for an
automatic Repeater Improvement Device as they incorporate the battery, VOX
activated transmit, and built in CTCSS tone generator.
With a little
ingenuity a simple device can easily be made to send the audio through the
jack input, set to VOX and automatically transmit as long as the audio is present.
advantage is the cost and easily found supply of Power Packs or mobile phone
chargers, which can power the device for long periods, and are easy to
recharge from any USB supply. A much cheaper option than higher capacity
For 2 Metre
repeaters a simple ¼ wave wire antenna is usually more than adequate.
This needs to be 48.5 Cms long or 19.2 inches.
The easiest way is to just strip
and cut back the screening on a length of coax, this will actually work
far better than the rubber antenna that is supplied with the radio.
Experimentation with antennae can
show remarkable effects, we had a very successful remote mounted device
that used a wire with a crocodile clip, this was clipped to the top wire
on a barbed wire fence, and had the strange property of transmitting
for miles whilst being very difficult to locate as the signal seemed to
come from a wide area, in fact the whole field. This had the odd side
effect of appearing the be intermittent as when it was raining or damp,
the transmitted signal was almost non existent. This was a lucky
advantage as the last thing you need is for your handiwork to be found
and stolen by your fellow hobbyists.
Keep it simple at
first, an ideal audio source can be found in musical or speaking greeting cards.
As you can see, they are small, cheap, and their audio output is just the right level
to be connected directly to the microphone input. Throw away the silly button cell, and power it from an AA
battery or from part of the device's power source. No more than 1.5 Volts
We favour the Yuasa 12 Volt jelly cells used as standby power on
burglar alarms, these are relatively cheap, but do not try recharging them with
a car battery charger, they need a low powered trickle charger.
construction of the bug
A decent R.F. proof housing needs to be used for a device made from a
transmitter board, there are some ideal die-cast alloy boxes on eBay.
In our original designs, all the components, including the battery, were in
the same casing. This was sealed against rain with silicone sealant, with an
insulated connector for recharging the battery. This worked quite well until
the small amount of gas given off from the lead acid jelly cell whilst
charging, started to corrode the tracks on the circuit board!
We now favour the transmitter,
audio source, and timers being sealed inside their own waterproof die
cast metal casing, with the battery attached externally by power
leads. The Yuasa batteries are quite capable of being exposed to
the atmosphere with no detrimental effects, and this design has distinct
advantages, we just put a couple of rubber bands round the 2 items.
No possibility of corrosion due to acid fumes,
and the batteries are easily changed.
In the past, a well sited device needed to be collected, taken home and
re-charged, then replaced in its hiding place. With a separate battery you do
not run the risk of being found with the device in your possession either at
home, or to and from the site. Thus a possible source of problem is completely
removed as you can simply change over the battery as and when it needs
replacing. A 15 to 20 second blast every 30 mins usually gives at least 8 days
use. It is unwise to regularly change batteries, for example, every
Sunday afternoon. It is best to be as random as possible, and even leave
a discharged unit for over a week before recovery.
A 1.9 A Hr battery will give at least a full week of 24 Hr. use at our recommended
intervals, that is no more than 2, 30 second bursts in any hour. As we have
already said, our extensive tests have shown that this gives the required
amount of annoyance coupled with a great degree of difficulty for DFers!
For devices made with old handhelds, a plastic case is usually good
enough, as the radio has enough R.F. screening in its own case.
One of our most
successful campaigns used 3 identical devices, all timed by quartz
chiming clock modules, set to go off at 20 minute intervals. The 3
devices were 15 miles or more apart across 2 counties, but still
each one was in line of sight to the target repeater, it still brings
a smile to my face now, remembering the monitored conversations of
the people who spent night after night trying to locate what they
thought was just one device.
15-20 seconds an hour might not sound much, but getting a blast of
Laughing Policeman Song 3 times an hour really sent some of the
straight laced buffoons right to the edge, and whilst they spent
every night racing round the countryside in 2 or more cars, we
stayed at home in the warmth listening to their fruitless search
tactics on 70Cms, very satisfying.
100% success! Now fully documented
locations can be quite interesting. Devices can be placed either in
built up areas or in the countryside, ideally, within line of sight of a repeater. They need to be
camouflaged to a certain extent to avoid being found accidentally.
We recommend the use of a handheld to test
the sites selected. Set your radio for the LOWEST output, we suggest a few
milli-Watts, if you can still open the repeater, then the device will as well!
This aspect of the hobby can be
more informative, rewarding, and educating than many of the more legitimate
pursuits of the cardigan and sandals brigade!
There are no end of possibilities for the
ingenious here. Some very sophisticated devices have been made with digital
speech modules, a vast improvement over the original auto-reverse walkman we
used in our Mk.3 model!
Technical progress has brought the price of
these modules down to just a few pounds, and they have the advantage of non-volatile
memories, so they retain the message or music even when the power is removed.
One of our members, who travels the country on
business, has a very nice gadget that plugs into the mike socket of the Yaesu
radio in his car. It plays small snippets of songs and abuse at random intervals
from a neat sound module, and draws its power from the mike socket. Limitations
of this aspect of our hobby will only be brought about through your lack of
Phantom Repeater Fault Module
An interesting and
simple device was made by an LPWS member that transmitted only a very
low-power carrier wave on the repeater input frequency, no sound and no
tone-burst. When someone used the repeater, all seemed OK until they
stopped talking, the repeater was then held "open" by the lower power bug, it
would eventually 'time out' as repeaters usually have a maximum transmit
duration built in.
You have to think
about it, as it is not readily obvious what this 'easy to make' device can
do, if you are on the repeater committee it looks like a serious fault
has occurred that has to be rectified, to the casual listener it's not obvious.
However, this has the effect of targeting the very group of hard-core nutters that matter, the demented repeater keeper and his cronies, it'll
have them pulling their hair out - if they have any left.
The power was
so low that it was impossible to locate, with the repeater's transmit signal firing up
every few minutes. It was powered by 4 AA rechargeable cells, which gave
it a little over a full day's use. The repeater group still have no idea
about this device, their reaction was to assume the logic was at fault
and constantly take the repeater apart!
The device was
recovered every few days, recharged, then replaced. The repeater group
then assumed the logic circuitry at fault again, and they spent ages
trying to locate the fault. Dead simple, highly effective, and cheap,
and they are still none the wiser!
Here is a picture of
the actual device
Made from a virtually scrap device
bought at a rally for £5.00, subsequent variations have been made just
10% of this size, using the much smaller crystal controlled bugs, the
only factor controlling the size being the power source.
With the advent of cheap Chinese handheld
radios such as Boafeng etc. devices can be made far easier and much
more economically than before. At the time, £50 for the circuit and
a suitable crystal was considered cheap, now complete dual band
radios with a battery are on eBay for less than £20.00!
The crystal controlled
transmitters shown below date from the last century and we'll leave
the pictures here as a matter of record.
commercially available crystal controlled transmitter modules.
All you need
is 48.5Cms of thin wire for an antenna, and off you go.
At this low power, antenna matching is
not a problem, in a rural situation you can actually use a length of
barbed wire fence, for example, as a long wire antenna. A prototype we
tested was constructed in a small black plastic box with just a wire and
crocodile clip protruding, this was attached to the fence wire and
provided a carrier strong enough to hold the repeater input open, over 2
Total cost, under £50, entertainment
value £ PRICELESS!
2011 - Components for a RID
(Repeater Improvement Device)
A quick look around the Internet
has brought up good sources of parts to make your own Repeater Bug.
You can't beat a second-hand
handheld as the transmitter, reliable, re-tuneable, usually with a
tone-burst included and small. Check Ebay.
Digital Recording Module, sound
source, just the job and very cheap
Quartz Clock Movements:-
We can't find any identical
quartz movements at the moment, the ones the LPWS used were
standard quartz clock movements with a pair of contacts that
momentarily made contact "on the hour" and triggered an external
This is one of the chiming
quartz clock movements, the 2 wires "make" momentarily every
hour to provide the trigger for the timer. OK not high tech, but
experience shows that electronic timers don't like being in
close proximity (inside the same box!) to local RF sources.
Advantages:- It works, the
battery lasts >6 months, cheap, accurate - so you know when in
the hour the device will be triggered, small.
Audio Source/Digital Sound Module 2012
Many thanks to G6JNS for
emailing details of this marvellous device! It works, it's cheap, and it's
With 20 seconds recording time
it is the ideal sound source for a Repeater Improvement Device,
20 seconds might not sound much, but it is just about perfect.
The output is OK to use straight across the microphone input of
most handheld transceivers or you can retain the speaker for
The microphone for recording your sounds or message is on the
right, the other 2 components are the push to record button, and
the push to play button. The latter would be replaced with a
trigger from the timer or a simple tiny relay will do.
Designed to run on 6 volts, but seems to work quite well below