Renewed interest in the
LPWS in 2011 has brought to light the story of
the evolution of the GB3MH Laughing Boxes.
We have just been
contacted by a long serving LPWS member who gave
us 2 of the remaining boxes he built, and told
us the history, many thanks!
Below is a
mildly re-written version of the write-up he
sent me, all I have done is correct spelling and
grammar, no changes have been made to the
With all the other
repeaters in the Midlands area well served with
jammers etc, GB3MH remained fairly quiet, so in
the late 1980's it was decided to give this
languishing repeater a bit of a going over.
GB3MH was in a prominent position on the Malvern
Hills and, we believe, shared a mast with many
other services including some operated by RRE
Malvern. The hills are the highest point for
miles around, and the tower's red light could
easily be seen from over 50 miles away.
Operated by a bunch of
loonies from Worcester, the repeater group were
particularly badly served by GB3MH due to
Worcester being at low altitude, when
surrounding areas much further away, had a line
of sight view of the tower and a much lower
powered signal could blot out much more powerful
stations in the Worcester area. The mast was not
actually on top of the hill so coverage was very
directional over Worcestershire. When driving
just over the hill, the GB3MH signal would fade
away and at about 1 mile down the other side of
the hill, it could be barely heard.
© Copyright Angus
licensed for reuse under this Creative
prototypes were very crude by today's standards,
but experience taught us that simple was better.
We actually lost the first prototype, it was
stolen by a group of amateurs from Worcester,
but it was hardly hidden, just on test. A
valuable lesson was learnt, so possibly money
well spent, as we never lost another device
after that one.
One of our very early
boxes was accidentally remarkably successful.
It did nothing much really, however the anger at
what this simple device did, exceeded anyone's
Nicknamed by the local
hams "Tony Tone-Burst", it was
originally deployed just to test the timer and
tone-burst, and to see if it worked well out in
the field, and if it would access GB3MH without the benefit of a proper
All it did was
periodically transmit a 500 millisecond access
tone-burst, but due to a complete fluke in the
setting of the timing interval, it would resend
the access tone-burst as the repeater was
closing down and was sending the Morse ID. This
meant that GB3MH was kept active with just a
very short ½ second transmission burst, for
reasons we can't imagine, no one would attempt
to use the repeater when this device was
at least 3 of these in smallish die cast alloy
boxes, running on NiCads, one had a small coiled
antenna plugged into a BNC connector, and 2 with
¼ wave wire and a
The first one could be deployed anywhere, the
antenna could be removed and the unit plugged into a car
or at someone's home.
with crocodile clips would either run alone or attached to fencing or barbed wire somewhere in the countryside
where the Malvern Hills could be seen,
experimentation had shown that this worked well,
even in the rain and some 30 miles away from the
repeater. We assume that it transmitted
using a kind of "long wire" antenna. It did work
remarkably well, but we don't exactly know why.
A good feature of this simple device was that the
batteries lasted almost a week, we tried leaving
one hidden in Auction Rooms in Malvern, it ran
24 hours a day for over 6 days, and was recovered from
its hiding place, on top of a cabinet, some 2
weeks later at the next auction.
honest about this, most radio amateurs are not
"quick on the uptake", it was almost universally
believed that this wasn't automatic, the loonies
actually thought someone was sitting there
pressing the tone-burst every 40 seconds or so,
variation of this device was a simple timer
circuit with a small relay built into a small
plastic box on the end of a lead with a mike
plug on the end. I saw this being used on an
ICOM, the 2 sets of contacts on the tiny relay
made a circuit between the pins for the PTT
switch and the radio's built in tone-burst, the real beauty of
this device was that 12 volts were available on
the mike socket, so all you had to do was plug
it in, no battery required. This was a novel
adaptation, and cost less than £15.00 to make.
The One They Couldn't Find!
After these tests had shown what was
possible, more elaborate devices were made. There were
NO digital recording devices at the time, so the only useable
audio source was an auto-reverse Walkman style AIWA
cassette player. This worked, but the total power
requirement was too great. After a meeting, and a "whip
round" it was decided to make a more elaborate version of
this device for a countryside location.
A Yagi 3
element beam was sprayed matt black, and with the help
of a 3 section ladder, it was fixed way up in a tree,
and pointed at the Malvern Mast. The box of electronics
consisted of 2 chiming quartz clock mechanisms set 30
minutes apart to trigger the 30 second timer. The
Tone-burst and transmitter boards were supplied by Wood
& Douglas, both quite good and robust. The tone-burst
automatically sounded when power was applied to the 1
Watt transmitter. Experimentation showed that hard
wiring the audio from the Walkman to the mike input
didn't work, it seemed to pick up too much local RF, so
a small mike was fixed in front of the speaker of the Walkman,
which was set to play auto-reverse with a tape of the
laugh from the Laughing Policeman Song.
The antenna was connected to the
transmitter and Walkman box which was also placed high
up in the tree. The clever part of this set up was that
a black cable was run down the tree trunk and attached with Evo-Stick, where it reached the ground, a shallow trench
was dug and the cable went underground to emerge inside
a pile of logs some distance away. Here, we were able to
hide a car battery to remotely power the tree-top
All you had to do was clip
the battery on, and off it went, twice an hour,
This was a quite expensive project, the transmitter
and tone-burst cost about £100 from Wood & Douglas, the same for the
Walkman, add to that a roll of black twin power
cable, plus about £25 for a
decent car battery, but it was highly successful, and
even though it was D-Effed 100%, they couldn't find it! Their search was listened to on 70Cms, as they thought
we were unlikely to hear them on that band. It is still
funny today, to think back and to have seen all the
undergrowth and grass round the tree flattened and downtrodden, but the device still
operating. THE WANKERS COULDN'T FIND IT, despite being
within 20m of it, what a bloody hoot! It's hard to imagine how they felt.
After the location was
discovered, we didn't use it so much and it was
eventually recovered and the parts used again in
other devices although during this period we
duplicated the effect from several people's homes in
the area, just to keep them guessing.
An important lesson was learnt here, you can't use a
fixed location as someone will eventually find the
device and steal it, so we embarked on designing a
different type of device.
The main problems we came across with the prototypes
were ingress of water and power supplies that would last
a reasonable time.
There was no way we could find a useable remote
mains power source,
so we had to use battery power. At the time there were
NO NiMh cells and no one had even thought of lithium ion,
so lead acid jelly batteries from burglar alarms were
used, luckily one of our members worked in this field
and we were able to use nice compact 1.2Ah battery.
When we were making these, someone had a
greeting card sent to them that had a small circuit and
battery inside that laughed when you opened the card,
brilliant, no need for the Walkman any more, £100 per
unit saved. The audio output from the laughing chips
worked straight into the mike connector. These cards cost
around £5.00 each, they came
with 1.5v button cells but these were replaced with Duracel AA cells, we never had to replace one.
To confuse the opposition,
which was 100% successful, we deployed 3 identical
devices. Chiming quartz clock mechanisms were found
to be very cheap timers, exactly the same as an
ordinary clock movement but with 2 wires that
momentarily completed a circuit once an hour. We set
these 20 minutes apart so the 20-30 seconds of "the
laugh" went off 3 times per hour, 24 hours per day.
We found that this was more than enough to send the
hard core loonies right round the twist!
Each box was in vastly
different areas, but all with line of sight to the
repeater mast, and each box had at least 2
locations. Each box was looked after by different
people. It was their job to deploy the device,
monitor the repeater for their box, which would be
on the hour, 20 minutes past, and 20 minutes to.
When the battery gave out, collect the box,
recharge, and re-deploy in the alternate location.
It sounds like a lot of effort, but it was really no
trouble at all.
Experience dictated that
this was the best way to achieve the most, with the
minimum of effort, and with virtually no chance of
anyone ever finding a transmitter box, unless it was
by complete chance.
It was interesting listening
to the DF crews on 70Cms, who had no idea what they
were looking for, and no idea where they were they
were hidden. It was a widely held belief that
someone was driving about the area, that was their
only conclusion when, after waiting another 20
minutes with the signal coming from a completely
As you can see from the pictures, they are dead
crude, but they worked and they worked well, which is
all that matters. As you can see, the main transmitter
is secured by the power transistor heat sink, the
tone-burst is also bolted to the casing. The laughing
module is powered by an AA cell, and the 555 timer
circuit is triggered by the pulse from chiming clock
mechanisms. A waterproof power switch and an insulated
tag for recharging complete the design, which was sealed
into a die cast project box with silicone.
A slight problem we found with this design, was that
the battery would give off a gas when recharging, that
corroded the printed circuit of the transmitter board. The
final version was much smaller with the battery outside the alloy case, this
cured all the problems, but we were aware this could
cause alarm if any of the units were found as it looked
like a cartoon depiction of a time bomb. Luckily, LPWS
newer had this problem, unlike the well reported
copy-cat devices made in the Aylesbury area.
*NOTE I asked
why only one had a mounting bracket fitted,
it seems that the other one used to have a
hook made from a coat hanger. It was formed
into a loop at one end and slid over the BNC
connector before attaching the antenna, the
other end formed a hook which was used to
hang it in a tree or in a hedge. The idea
was to attempt to use whatever it was hooked
to as a ground plane. A fair idea, but I
doubt if it made the slightest difference.
We are grateful
for the supply of the 2 remaining boxes,
which we are now going to open and share
the pictures with you.
These are crude
devices, but trial and error dictated
this design, and the fact that they were
never located and never failed in use
bears this out.
These 2 boxes were made by the same
person a few weeks apart and have
remained sealed since the very early
When we finally
got one of the boxes open, the first
time in 20 years, we were surprised to
find it in remarkably good order. The
digital recording module had lost its
audio as the 6v battery pack was flat.
All 3 quartz clock movements were silent
as the batteries were flat. (we were
expecting only one timer in this box).
However, upon applying 12 volts to the
transmitter, IT STILL WORKED!
This is one of
the 3 boxes, and with very minimal signs
I was previously
unaware of any box that went off 3 times
per hour, as this one obviously did, but
I expect that when up and running with 2
others, finding the direction of the
signal on the repeater input channel
would be a virtual impossibility.
Dead simple, if
crude construction, in modules. The
quartz clocks tripped the transmit
interval timer, this supplied power to
the transmitter and started the digital
recorder. The tone-burst automatically
sounded for 500mS when power was
applied. This set off a recording of the
laugh from Charles Penrose's Laughing
Policeman Song. Dead simple, dead
reliable, and dead annoying.
These 2 devices
were placed in different locations, the
clocks were set to trigger the laugh at
20 minute intervals, with box number 2
set 10 minutes apart. The result was 28
seconds or so of "The Laugh" sounding
every 10 minutes, first from location 1,
then from location 2 etc.
very well for years and no one ever
found one, the resulting mayhem on the
repeater was often hilarious!
Great effort was
made to find them, but without any of
the "opposition" knowing what they were
looking for, they spent a long time
driving around and DFing the signals
with the conclusion that the signal
source had to be mobile.
amongst the several locations were a
hedge, a barn, an apple orchard, and
hung in trees with a hook made from an
old coat hanger. Collection and recharge
was done on a rota basis by several LPWS
members, before they were re-deployed at
Sadly GB3MH is
no longer active and the replacement
repeater, GB3NW, is now not in such a
good position for this kind of fun.
Plans are in
hand for a CTCSS based device using one
of the cheap Boafeng radios as the