Contents of an Amateur
Radio Shack
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I'm depicting below the
amateur radio gear owned by my pal Tony Trigell, G3JAF who sadly
is now a silent key. In no particular order, just as I tidy it
up and take photographs. |
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Above is an old KW600
Linear. This is complete with integral power supply so is pretty
heavy. British amateur radio equipment has a particular look
about it which is completely different to Japanese imports. Stuff
made in the USA can look externally similar to British equipment
but is completely different inside. Click the picture to see
its operating instructions. The linear uses a single 572B in
grounded grid running at around 2000 volts on its anode. To drive
the linear to full output needs an input power of around 20 watts
RMS (two tone SSB). At rated output the linear consumes 180mA
at 2000 volts so, if you do the arithmetic, it's all a bit odd.
UK regulations say that you shouldn't put more than 100 watts
RMS into an aerial and makes the assumption that this should
be produced from 150 watts DC input. Of course SSB messed up
this simplicity and manufacturers of linears moved from DC input
to PEP input. For a two tone input, which will result in a measurable
DC power input I get 360 watts. |
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This rig is a Yaesu FT-726R
which covers three VHF/UHF bands. Click the picture to see a
user manual. Despite its relatively large size (because it needs
to accommodate three separate RF modules 6m, 2m and 70cm plus
its power suppy), it delivers only 10 watts output. The case
measures 13" wide x 5" high x 12.5" deep and it
weighs in at over 24 pounds. |
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This transceiver is badged
as a Trio TS-940S but will be recognisable in countries other
than the UK as a Kenwood. This rig is particularly attractive
because it not only transmits on all the HF amateur bands but
it has a general coverage receiver tuning from 150KHz to 30MHz.
No worries about a power supply either because it's built into
the case although this does make the thing extremely heavy. Ages ago I repaired this rig when Tony reported
it was deaf. Because these sets are now getting on in years
they suffer from various problems... the worst being failure
of the mains transformer. Because of this type of fault you'll
see lots of spare parts offered for sale as transformer replacement
is not easy. Click the picture to see the user manual. |
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Above is pictured a loudspeaker
from Yaesu, the SP-102 having
a useful two-way source switch and filters for improving audio.
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Below is a useful piece of kit.
This can be used for connecting a single broadband aerial such
as a discone to a multiband rig. I imagine Tony used this to
connect his FT-726R, which has separate
aerial sockets for each of its three bands, to a single aerial. |
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Below
a 2-meter Yaesu FT-480 all-mode transceiver which appears
to need a little cosmetic attention. |
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Here's
a 70cm FM rig, a Yaesu FT-730R. |
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Below,
a CB rig, a Jaws Mark 2. |
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Below
is another 2 metre rig, but for FM only, a Yaesu FT-2200. |
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Above is an SWR/Power Meter
good for reading up to 2000 watts peak, a PM-2000. Looking on
the Net for this instrument led me to the Swan WM-3000 which
appears to be the same thing? Their
other offering the WM-2000 integrates the SWR function into the
main switch. A mains power lead (and the indicator lamp)
tells me this wattmeter is not a passive instrument and on removing
the cover this is what's inside. The 8-pin chip is a uPC151C
which is a replacement for an uA741 op amp. The vertical board
on the right has a set of 8 preset pots. |
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The Tono linear above
can boost the power output of any of the 2 metre rigs shown above
to 100 watts RMS... and below,a
B.N.O.S.
linear good for 180 watts RMS given 10 watts input at 2 metres.
To
see it's circuit board click the picture below |
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Below,
a Microwave Modules linear designed for increasing the power
of a 10 watt 70cm transmitter up to 100 watts RMS. |
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Many of the rigs shown above
need a 12-volt power supply, and this being a relatively low
voltage, needs to deliver a lot of amps. For example the 2 meter
180 watt linear amplifier running at say 70% efficiency will
demand 12 volts at nearly 22 amps and, if the same power supply
is being used to power the transceiver, you can add a further
few amps and fully expect the voltage to remain stable.
Below
I've pictured the power supply used by Tony. This is badged "Kingshill
Type S560B" and being British has that rugged not-at-all-stylish
design which far eastern products usually avoid. On the other
hand far eastern products seem to look rather puny compared with
this lump. |
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The outer case looks like
it was an afterthought knocked up by a cost saving boss. |
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Maybe the transformer
cost more than planned or someone miscalculated the number of
capacitors needed? Not to mention the dozens of stabilizing transistors... |
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Now, a puzzle. It concerns
a 2m transceiver, the Azden PCS3000 |
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This tidy 2m FM transceiver was sitting
at the back of a top shelf in two parts. When this set was designed
it had a useful feature whereby the front panel assembly could
be unplugged from the chassis and removed or hidden away thus
disguising the fact that an expensive looking piece of kit was
present in the car. The puzzle is that the front part didn't
plug into the back half because the locating key was in the wrong
place. |
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Here's the front view of the chassis
part of the rig.
You'll note the key is now correctly
fitted at position 6 from 16.
Below is the front panel assembly with
the slot now matching the key after an hour or so of work. |
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From the damaged track it's obvious
that someone had been here before, but why on earth change the
key to a position that didn't match the front panel?
This picture shows the connector board
after repositioning the key and contacts. |
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What's the round thing under the
label? |
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I dismantled the chassis and removed
the front panel holding the connector, then detached the connector
which is fitted to a small circuit board.
Why did I do this?
Because, when I examined the front panel
and the chassis to discover why they didn't plug together I found
the key was fitted in location 7 instead of 6.
Marks around postion 6 showed the key
had been fiited there but had been deliberately moved and the
connector contacts also moved from position 7 to 6.
because of this the two parts of the
rig didn't plug together. |
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To fix the problem I removed the
key and the contacts and swapped them around. This meant unsoldering
the connector from its board as the contact sets are pushed out
from undeneath. The tiny cracks by the key were made by whoever
initially removed the key before moving it to the left. |
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Here's something interesting. The
original VHF power module has been removed and a smaller
Toshiba version fitted. Trying to figure out what's been
going on.... I think the rig failed and was given to a repairer.
Note the evidence in the sticky label fitted to the top of the
front panel. Presumably a faulty power module was diagnosed and
a replacement Toshiba part fitted? Then things get puzzling.
Why was the connector modified so that the two parts wouldn't
mate together? My guess is the repairer didn't fix the problem
and handed back the two parts with a suitable apology, but substituted
one of these either to keep a better part for himself and hand
back not one, but two unrepairable parts? I'm open to explanations
and may try the rig now that the two parts mate together. Click the picture to see the spec for the
new power module. |
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After correcting the socket key problem
I was able to plug the front panel into the chassis. Next...
what would happen when I powered the rig?
Using a variable voltage power supply
with an adjustable current limit. I set the current to 100mA
and increased the voltage. No short-circuit and I heard a squeak
from the loudspeaker. The voltage had dropped from nominal so
I gradually increased the current so that eventually at 12 volts
the rig was drawing around 350mA and the speaker produced a harsh
FM hiss which varied with the volume control and worked correctly
using the squelch knob. The display showed a single digit for
MHz and three digits for KHz. I switched it off and on again
and found the display didn't always light up. When it was lit
the MHz figure sometimes, but not regularly, stepped up about
once per second. After ten minutes experimenting I suspected
an intermittent, maybe a dry joint, that made the rig unstable.
I looked for a high shelf on which I could dump it.... but maybe
the problem could be found and rectified? I put it on one side...
being probably not the first to do this.
Having a spot of spare time I checked
inside the front panel box and disconnected a 4.8 volt NiCad
which was past its best and reading only 120mV. Instead, I fitted
a 1F capacitor which I had handy. Turning on the rig I still
noticed the frequency display went off or didn't materialize
(just a green dot) at random. Sometimes it would reappear by
itself. Using a signal generator I found the receiver tuned correctly
to a 2m signal and, when the display went off, the tuning buttons
were unresponsive, leaving the receiver tuned to its last setting.
I removed the microprocessor chip and cleaned its heavily tarnished
legs but that didn't improve matters. There are a few tiny electrolytics
present so maybe I'll test these later? |
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