This page has
on some of
on. These are
can should build, but just remember Byrne’s Law:
In any electrical circuit, appliances and wiring will burn out to protect the fuses.
- Homebrew PCBs - tips on making one-off or small-run printed circuit boards
- Meter scales - techniques for re-labelling meters
- QRO baluns - high power 1:1 and 4:1 baluns for dipoles, loops, open-wire feeders etc.
- Mains voltmeter - a very simple yet handy project for a wet afternoon
- Bencher dust cover - another simple rainy-day project
- Kenwood radio-to-PC interface - a homebrew version of the IF232
- Remote ATU - a long-term work-in-progress
- Rotator control box repair - large 4WD meets delicate Japanese electronics
- GS35b HF amplifier - another work-in-progress or ‘one day project’
- Remote antenna switch - multiple antennas out in the field share the same low-loss feeder
- Manual antenna switch - a handy shack accessory, much cheaper to build than buy
- Find true North - all you really need is a stick, a sunny day, and the Internet
- QRP rigs - homebrewing low power radios just for the sheer hell of it
- A ham’s workbench - where the above happens
- Keep notes - use a notebook, not just your logbook
[There are other homebrew projects on this site too, including Elecraft rigs and antennas.]
Access to the amateur bands is a privilege that comes with a purpose - ‘self training in radio
communication’ as the old UK license used to say ... and maybe still does. I shudder when I see the
price of simple ham accessories and antennas made and sold commercially, especially when
making your own is both instructive and fun. Even better, I can often build better quality, longer
lasting items than I can buy, for the simple stuff anyway. After all, I’m just a hobbyist, not an
electronics or engineering guru. I don’t have an electronics degree but I’ve taught myself enough
skills to get by, and making simple gadgets for the station or shack, or repairing things I’ve broken,
is the most enjoyable way of picking up new ones.
At the Napier radio club, Erroll ZL2IT demonstrated the toner-transfer method of homebrewing
Printed Circuit Boards at home, in one-off quantities. As far as I recall (I haven’t actually tried this
myself, yet), this is roughly how it’s done:
Design your circuit and board using your choice of circuit design apps. Erroll recommended an
online app but I missed its name - possibly EasyEDA?
-print a full-size mirror-image of the board onto shiny coated paper (it must be a laser,
not an ink jet or dot-matrix). The backing sheets for laser-printer-friendly sticky labels work
well, apparently, while glossy advertisements (such as the real estate newsletters) are OK
too. Plain office paper is no good because the toner bonds to the paper. Erroll mentioned
using a specific paper/size setting - an envelope I think it was? Not sure. Some
experimentation may be required here, depending on your printer, to get the setup just right.
Plain paper is fine for that!
Prepare the PCB blank. Cut it to size. Clean/de-grease the copper thoroughly using a
scourer and detergent or solvent (isopropanol, ethanol/meths, acetone ...). Hold the board
only by the edges from now until it is etched.
Borrow a clothes iron. Set it to its maximum heat and let it get hot.
Place the PCB face-up on an ironing board or similar surface. Place the printed design toner
-side down on the board, making sure the printed design aligns with the board (Erroll trims
the paper to size to make that easier). Place a sheet of kitchen-roll (absorbent paper towel)
on top of that to avoid the iron snagging or sticking to the coated paper.
Iron the design onto the board with the hot iron. Press gently for about 2 minutes. The
kitchen-roll may go brown but it shouldn’t burn. [A hot laminator may work instead but the
rollers may be damaged due to the thickness of the board.]
Wait a bit for the board to cool, then carefully peel back the paper leaving the toner on the
board, hopefully. Admire your handiwork. If it hasn’t worked out, go back to step 2 and try
again, adjusting as necessary and making notes for next time.
Etch the board using a solution of ammonium persulphate to dissolve the exposed copper,
leaving behind the copper protected by the toner. Erroll says it works better than old-school
ferric chloride and can be re-used, adding an extra spoon of chemical if the etching slows
down. Warming the solution speeds the reaction but it shouldn’t take long anyway - just a
few minutes. Use a disposable plastic container such as one of those microwavable tubs
liberated from your Chinese take-away, not the best crockery. And take care: these are
nasty chemicals that will etch your skin and cornea if you splash them about.
Wash and clean the etched board, removing the toner with a scourer I guess.
Drill the component holes carefully using a fine drill, preferably in a bench drill or drill stand.
Clean/de-grease the board once again to remove any finger prints etc. that will prevent the
solder flowing and bonding to the copper. Cleanliness is vital: use the bright and shiny board
as soon as possible, before it starts to tarnish.
Place and solder the components.
Test. Refine your design and repeat the process until done.
Send the completed design as a Gerber file to a PCB manufacturer if you feel the need to
achieve a more professional finish, especially if you are preparing more than just a handful of
Erroll says he has made boards this way for surface mount as well as through-hole components,
so the toner-transfer method works even for those fine traces.
I have homebrewed with other PCB prototyping methods in the past, using various etch-resistors
(e.g. covering the whole board in a layer of insulation tape, then cutting the traces with a scalpel;
enamel paint scratched away with a scribe; Dalo etch-resist marker pen), or directly removing the
copper with a Dremel-type grinder or hacksaw: the results were crude and ugly but usable for
through-hole work, not for surface-mount though.
Milling away the copper is another method if you have access to a suitable milling machine. I don’t.
Veroboard (stripboard) is yet another possibility, along with the Manhatten technique (components
are super-glued to the board with their legs in the air, using the board simply as a mechanical
support and earth plane) and the PCB island method (little PCB pads are superglued to the main
PCB earth plane at strategic points).
Decades ago, tag boards were all the rage ... but back then resistors were an inch long,
condensers were even bigger and valves used High Tension referring to both the voltage and the
possibility of imminent failure. Standoff insulators fixed to the chassis are still used in valve amps,
as well as Frankenstein movies. More power Igor!
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I’ve used Letraset rub-down transfer letters to re-label old meter faces before but these days the
computer makes a better job of it than I do. Here are two suitable techniques:
Tonne Software offers the nifty Meter program to create meter scales from scratch. It’s a
fiddly process to get the scales positioned and sized just right but sometimes that’s what it
takes. Even non-linear scales for SWR meters are possible.
David G4FTC scans the old meter face on a flatbed scanner, adapts the image using a
graphics editor, and prints it on a label to stick on the rear of the original face (in case he
wants to go back to the original). I guess you’d need to match the scanner and printer
resolutions to get the size right but that’s a neat idea, David. Tnx!
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In the US, it’s relatively easy to obtain QRO baluns but not so down
here on The Far Side. So, rather than pay an arm and a leg to
obtain a commercial balun from W-land via airmail, I decided to
have a go at making my own heavy-duty baluns capable of
matching my amp’s output to various antennas. The wonderful
book “Understanding, building, and using baluns and ununs - theory
and practical designs for the experimenter” by the late Jerry Sevick
W2FMI has been my inspiration and source of most of the ideas.
It’s a bit short on practical construction advice though and presents
a confusing range of options including many designs lifted from the
amateur literature and (mostly) systematically dismantled as a
result of Jerry building and testing them (theory <> practice).
Lacking the ability myself to measure losses, impedance
transformations, frequency response etc., I’m simply sticking to
W2FMI’s preferred designs.
The next step was to find a source of toroids. Again, small toroids are sold in ZL but not the large
ones (e.g. the FT240 with an outside diameter of 2.4”) suitable for QRO power levels. On a
recommendation I went to Amidon’s site and found all I need right there. The “K” material ferrite
has a permeability of 290 and is good for LF toroids while the cheaper “61” material has a
permeability of 125 and is fine for the higher HF bands. They also sell Teflon tubing and Thermalize
wire - although to be honest, I do just as well with coax inners. Amidon’s prices are reasonable and
delivery is quick and charged at their cost price.
The first project was a wide-range 4:1 balun using a man-sized T400A2 iron powder toroid,
designed to match balanced open wire feed to a normal unbalanced ATU. I didn’t fancy paying extra
for the copper wire and Teflon tubing suggested by
W2FMI so I improvised, using the core from a spare
length of RG58 coax which is more or less the same
size and hence probably
about the same
impedance and voltage
rating. 21 bifilar turns
took the inner from
about 5.6m of coax and
the discarded coax shield
will make earth straps
for other projects. The
toroid cost me US$30 +
post from Amidon. The nice grey gasket-sealed polycarbonate box
came from Dick Smith, our local high street electronics supplier, for
about US$15. It’s better than a metal box in this application as there
is no need for difficult-to-get HV feedthrough insulators on the
balanced side. At left are the parts laid out in kit form and the photo
at right shows construction in progress. Notice the 12” ruler under
the kit: this toroid is 4” in diameter and needs a box at least 5”
across to leave room for the windings.
Next I built 1:1 LF baluns (chokes) using FT-240-K cores (US $18.50
ea + post) and more RG58 offcuts. These were even easier to make
with no need to strip off the coax outer cover and shield. I use them
to feed HF dipoles using RG58. Ten turns of RG58 takes about 88cm
of coax but I’ve found it’s best to just use the end of the feeder,
running it through a cable gland into the box, eliminating the SO239
and PL259 and another fraction of a dB of loss!
Be careful with those toroids. The ferrite ones are more fragile than
the iron powder ones and can be snapped by over-tightening the
The plastic box is not strong enough to use by itself as
a dipole centre for long dipoles so I normally use
ceramic open wire spreaders, attached to the balun box
using cable ties (two on the Mark I, four on the new
improved Mk II) held in the boxes by jamming the cable
tie heads into the box mounting holes from behind.
The antenna connectors use 5mm stainless steel bolts
and wingnuts for convenience. The bolts and SO239 (if
used) are sealed with superglue which is liquid enough
to flow into the tiny gaps and goes rock hard,
preventing them from moving even under intense
pressure. The same goes for any fingers that stray into
the glue ...
It takes a bit of work to make neat holes in the polycarbonate boxes for SO239 sockets or cable
glands. First I drill a 13mm hole using the largest drill I have, then a tapered hand reamer to enlarge
it, and finish off with a circular file and (for the round sockets) a small flat file to flatten one side of
the hole to match the flat on the socket. This flat, along with the superglue, stops the socket from
turning while tightening the PL259 on the coax downlead. By the way, I always cover plugs used
outside with a layer of self-amalgamating tape to avoid corrosion and stop water getting into the
coax, topped off with a further layer of insulating tape to cut down on UV damage from the very
bright NZ sunshine.
The toroids are held in place in the boxes using offcuts of high density foam cut to size from an old
gardening kneeling pad. The rated efficiency of these toroidal baluns (around 98-99%) shouldn’t
cause any problems with overheating even at QRO levels, but I check them occasionally for heat
damage and moisture ingress. One advantage of constantly experimenting with new antennas is
that there are plenty of opportunities to check the connections!
Lately, I’ve been making 75 ohm 1:1 baluns for my fullwave loops. I simply wind a few turns of the
75R matching line around a toroid inside a box at the loop’s feedpoint. Dead simple and works
nicely. [To be honest, they are working at an impedance close to 100 ohms according to the
theory, but are absolutely fine in practice. My loops always outperform my dipoles. YMMV.]
One curious result to report: one of my usual 50R 1:1 choke/baluns created a noticeable
impedance mismatch for the club’s 10m Yagi. Possibly some sort of self-resonance effect? I must
remember to check out my baluns on the bands they are designed for in future using an antenna
analyser and resistor in place of the antenna ... which reminds me I need to dig out some 50R and
100R carbon resistors from my junk box and put them in the antenna analyser carry-bag.
Back to quick links
I have keyers, ATUs, filters,
computers and all sorts of
measuring gizmos, some of
it homebrew, some not. I
built a crude wooden box
(right) for an AC voltmeter
to keep an eye on the
mains and discover exactly
why the lights flicker when I
key the amp and go very
dim every so often (left).
Key to this project was finding this fabulous old 4” 300-degree movement AC voltmeter, made in
Auckland and liberated to the appreciative amateur market from a demolished NZ power station.
Then it was simply a case of knocking the electronics together one idle afternoon.
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A $10 dust cover for the Bencher paddle
I love my Benchers. I’ve tried various other paddles from time to time but, for whatever reason,
the Bencher iambic paddles suit my fist better than the rest.
The only slight drawback to them is that they collect dust. Aside from looking less shiny, the dust
sometimes shorts out the contacts at the very close spacing that I prefer. It’s easy enough to
clean the contacts by carefully sliding a plain piece of paper through the gap but it always worries
me that I’m slowly eroding the thin gold-flashed contacts.
The answer is a dust cover:
Thanks to a suggestion from my pal Lee ZL2AL, I made
this fetching lime green creation from a plastic box sold
as a desktop holder for square pads of notepaper. By
coincidence, the box is almost exactly the same size as
the Bencher base, although too high, and it has a cutout
that might have been made to fit over the paddles. All it
took was a bit of careful and patient work with a junior
hacksaw to cut the box in half, followed by smoothing
and straightening the edges with a fine file and emery
paper. I then cut up the cut-off section of box to make
four corners that overlap the base to hold it in place,
sticking them on with UHU clear glue.
The tabs are a tight fit across the width but have a bit of
leeway front and back.
If you try this at home, hunt around the local stationery stores for a box that doesn’t have four big
cutout holes in the base, or be prepared to cut and stick a piece of plastic in place to cover up the
holes. Mine is a “Durable” brand box with no holes, costing about $10 including a free stack of
notepaper slips. I like the fluoro green. Other colours are available.
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Kenwood radio to computer interface
The boring grey diecast box
here is my version of an
IF232C Kenwood radio to PC
interface for my old TS850’s.
It uses a MAX232 chip to
convert between 12V RS232
and 5V Kenwood standards. I
didn’t bother with opto
-isolators - no need. The
construction project was finally
completed in 2005 but started
about 5 to 10 years previous.
The RS232 connector on the
right is a commercial USB to
RS232 convertor because the
PC doesn’t have an RS232
serial port. At last I can log
frequencies directly from the
TS850 and avoid some of my
contest logging screwups, I
My K3 has the RS232 port
option fitted, but I’m still using
the same cheap USB-RS232
converter. FWIW my advice, contrary to dire warnings elsewhere, is not to fret about the particular
chipset your USB-RS232 converter uses: buy a try cheap one and just see if it works. If not, buy
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Remote control ATU
I picked up a pair of big motorised vacuum capacitors at a radio rally in North London several years
ago, and a couple of big motorised roller-coasters too. I'm hoping to finish a remote controlled
(manually-tuned) QRO ATU .... if only I can find the time to build it! So far, I've managed to get the
roller-coaster stepper motor drive working, and I've started to figure out how to control the
vacuum cap (10-1000pF variable plus 3 x 500pF fixed caps with RF relays in series). Unfortunately
, the vacuum cap units are earthed through the cap chassis so for a balanced feeder I’ll probably
need to leave the chassis floating (a technique I've used for years). I may go for the dual-balanced
ATU design published by AG6K in QST Mar 1990, using an air-core balun instead of lossy ferrite.
Anyone out there fancy designing an auto ATU with PICs?
As you can tell, that’s an unfinished project.
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Ouch! Large 4WD meets small Daiwa rotator control
OK, it’s not exactly a construction project - more of a reconstruction.
This mess is the result of someone who shall remain nameless deciding to drive the car across the
field when I was assembling a new beam and rotator ready for CQ WW CW 2006. The rotator
control box was “hidden” in the long grass under a tree and while I worked on the pole 20m away,
that ‘someone’ drove out to the field to bring me a beer. Very nice. But then the ‘someone’ drove
off the track and back directly across the grass to the house with a sickening crunch as she passed
the tree. She didn’t even notice the new speed bump in the lawn, or the irate radio ham jumping up
and down in her ‘lipstick mirror’.
The wheel crossed the front left hand side of the box, crushing the indicator panel and case. First
job after we’d collected the pieces and I’d calmed down was to disassemble the box and assess
the internal damage....
The rotational indicator is basically clockwork: a series of gears, driven by a small electric motor,
turns the pointer and a potentiometer gives positional feedback to the electronics, a simple
Wheatstone bridge circuit.
With all the main bits out of the box, the front panel was buckled and above you can clearly see the
bent drive shaft for the indicator/pointer. So, with pointy-nose pliers in hand and nothing to lose by
having a go, I disassembled the gear box, straightened the shaft and reassembled it. The motor
didn’t work due to its wires being sheared inside the end cap near the commutator so some
precision shaping with a scalpel and soldering iron was called for. Amazingly enough, it worked!
After reassembling the innards, I painstakingly rebuilt the plastic box using superglue and a hot glue
gun to tack the fragments back together, and turned it upside-down so the worst bits don’t show
quite so much. I used clear sticky film to hold the cracked bits of the perspex front panel in place
rather than replacing it because it would be too hard to re-draw the compass bearing outer circle
by hand. Anyway, the cracked panel tells a story.
The repair cost me a day’s labour in the shack and workshop, and with no rotator there was no
way to turn the HF beam for CQ WW CW 2006, so I had a go at 40m single-band instead ... and
made a record Oceania score.
During 2007, I bought a shiny new control box for a Yaesu rotator that I’m planning to convert to
work the Daiwa, hopefully with a bit more oomph too since there is a fair bit of voltage drop on the
long rotator control cable at present (even using heavy duty “trailer cable”). That’s another “one
day project” (as in I’ll get around to it one day).
Meanwhile, I’ve fitted 4 x 12V white LEDs (a dollar a piece from Dick Smiths, NZ’s equivalent of
Radio Shack or Maplin - all three now QRT) behind the display of the old control box in place of the
temporary incandescent bulb which burnt a big brown blob into the Pacific Ocean (and they say
global warming is a myth!). The LEDs are powered off the 12-0-12v transformer taps with 2
diodes and no smoothing capacitor. The old control box really is a junker but still it refuses to die!
Now all I have to do is remember to fit the beam pointing the right way ... yup, you guessed it ...
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A “one day” project - a GS35b HF amplifier
I’ve been collecting bits to
build an HF amp to replace the
LK550 - one day. Thanks to
another ZL ham, I have a
chassis, a GS35b valve and a
little pile of circuit boards and
components, most of which
I’ve even found a suitable fan
to cool the beast, thanks to
stalking our ZL equivalent of
eBay for long enough.
I bought a meaty HV transformer from someone who dismantled several 5kW commercial
transmitters from an airport radio installation: it weighed about 90kg. Unfortunately, it turned out
to be an expensive mistake. A toroidal HV transformer will be much smaller, lighter and safer.
... Meanwhile I am thoroughly impressed with my KPA500 from Elecraft.
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Remote antenna switch
Having multiple antennas out in the field is great for diversity and flexibility but linking each one back
to the shack with high-quality coax feeder is both expensive and awkward. I much prefer to use
remote-controlled antenna switches at the far end of the main feeders, selecting antennas with a
small switch beside the rig.
For the Mark 1 remote switch I used heavy duty (high current) open frame 12V relays with big
contacts and decent change-over air gaps. Although not designed for RF switching, these worked
OK ... at least until water got into the box and they corroded away. The SWR was reasonable up to
The Mark 2 switch design uses vacuum relays from Russia and is great. Rainwater got into that box
too (spot the systematic failure mode!) and corroded the coils on two of the relays, since replaced
. The relay boxes now sit up on bricks inside plastic containers to (hopefully) keep them out of the
I recently rebuilt the Mark 1 switch with five more vacuum relays - the 6th relay has very narrow
contact spacing so I’ve kept it aside to use as a TX-RX change-over relay in the new amp as I
believe it will be a fast switcher.
Both switches use an identical control system, so the boxes are interchangeable. Relays are
selected simply by applying +24V or -24V (relative to the common ground) to one of three wires
in a separate control cable. I decided not to use the coax as a signalling line for fear of having to
isolate the control circuitry from QRO HF, and to avoid any chance of introducing nonlinearity that
might create sproggies on receive.
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Manual antenna switch
This is a surprisingly useful little gadget if, like me, you enjoy trying out different antennas and
comparing their performance. It sure beats plugging and unplugging antennas from the rig all the
time and it’s easy to make, and cheaper even than the flimsy rubbish often sold to/by hams.
A strong metal box - diecast aluminium boxes are good.
A good switch - about 3 to 6 ways, single pole, ideally a strong, high-voltage ceramic type for
longevity and if you will be running more than say 100W.
SO239 sockets - one per switch position plus one more for the input (unless you prefer to
use a coax tail with a PL259 connector - that’s not a bad idea as it reduces one connector
pair and cuts about 0.1dB of loss). If you are into UHF, use N-type sockets instead and
standardise your whole station on N-types. Given the choice, use good quality Teflon
-insulated sockets with a square metal mounting flange and 4 fixing bolt holes rather than the
round type with a large round nut, as the latter tend to work themselves loose over time.
Nuts and bolts to fix the SO239 sockets and, perhaps, the switch (depending on its design). If
you have a sizeable junk box, you may find enough similar ones for the project but it’s
probably worth buying sufficient new ones as they are cheap enough and look better.
Enamel spray paint.
Paint your box, unless you like that minimalist grey utilitarian look. You can do it later but then
you’ll have to dismantle or paint around the fixtures - it’s easier to do it now. Car paint or
Hammerite work well for me. Spray cans avoid the need to clearn your brushes but you need
to build up thin layers slowly to avoid unsightly runs. Let it dry for at least a day or two.
Mark the positions of the antenna connectors and switch on the box. Use a ruler to get them
lined up nicely. When you’ve decided where to drill, make small indents with a centre punch
(an automatic centre punch is a worthwhile investment). Double check that you have marked
all the holes in the right places before you start drilling.
Drill the holes. If you are under 16, get mummy to help. Always use good quality high speed
steel drill bits intended for cutting metal - cheap drill bits are both a bad investment and a
safety hazard. Wear safety specs and other safety gear if you anticipate becoming an old
ham. If you don’t have a large enough drill bit for the SO239s, ream out the largest holes you
can drill using a hand reamer or cone-shaped step drill bit (also worthwhile investments for
your toolbox, along with a pillar drill if you can). If you must, file them to size using a suitable
round metal file. Try to keep the holes round.
Fit the switch and the sockets to the box. Sign and date inside the box, perhaps with a
reference to this website, as you will forget what you have done in a few years. Put the lid on
the box and admire your handiwork.
Wire up the sockets to the switch using good RF techniques i.e. short, direct runs of wire,
preferably multi-stranded insulated wire of about 3-4mm diameter. Solder them. [I won’t
bother explaining the wiring diagram as if you need that level of help, this is not the hobby for
Test the box, using your rig or antenna analyser and either your antennas (if you know they
are resonant and well matched i.e. have a low SWR at the shack end of the coax) or better
yet a 50 ohm dummy load. A QRP load will do for the test as you should only need a watt or
two to get an SWR reading and confirm that every switch position works without creating a
mismatch i.e. the SWR readings should be practically identical whether the switch is in or out
Label the box. I use cheap sticky labels and a marker pen to identify which antennas are
connected to which positions because I’m always changing them, experimenting with new
Back to quick links
Find true North
Suppose you want to ensure your rotary beam is pointing precisely the right way: how do you do
it? There are several ways to find true North:
Use a magnetic compass
. Don’t forget to adjust the heading to account for the magnetic
declination - the offset between magnetic and true north - at your location. Here in Hawkes
Bay, New Zealand, the compass points to 21 degrees East, not true North. Standing beside
my tower under my beams, holding a compass, I have identified a specific tree about 200m
due North. Having turned the rotator to indicate North, I can climb the ladder, slacken the
bolts and turn the mast in the rotator until the beams point directly at the tree. Even easier, I
can adjust the rotator pointer without all that climbing and spannering.
Use the stars
e.g. Polaris, the pole star in the Northern hemisphere is less than a degree
away from true North. The Southern Cross in the Southern hemisphere points towards the
South pole but there is no distinctive star right at the pole, so we have to draw another
imaginary line from two pointer stars to locate it. If I had the equipment and the patience, I
could take a long exposure or time-lapse multi-exposure photograph of the starry skies, and
then work out the direction of the static point - like this one looking South from the Davis
Base on Antarctica (photo by Chris Hill).
Use the sun
First, an important warning:
DO NOT stare directly at the sun.
You can permanently
damage your eyesight. A brief glance that way, preferably wearing dark glasses, is all I dare
Various websites will calculate solar position relative to any location on Earth at any time of
day. My favourite is the NOAA site that lets us pick our exact QTH using Google Earth’s
excellent satellite maps, then displays useful info:
(1) Having determined your exact home location, save it for the next time you visit the site.
(2) At the calculated (local, clock) time of solar noon, the sun will be due North (in the
Southern hemisphere) or due South (in the Northern hemisphere) of you. Shortly before solar
noon, set your rotators North or South then go to your towers and, at solar noon, check
that the beams are pointing directly at or away from the sun. To make it easier in future,
mark where the tip of your tower shadow falls at solar noon: standing on that spot, the
boom of your beam should go directly away from you: looking up, it will appear to stand
vertically above the tower and stub mast in a straight line.
(3) If you can’t wait for the next solar noon, use the calculated sun’s azimuth setting right
now. The values shown on the NOAA website don’t update in real time, so click the Use
Current Time button to update the current suun’s Azimuth and Elevation values, set your
rotator to the calculated azimuth, and quickly confirm that the boom of your beam is pointing
directly at the sun.
A portable North finder
At solar noon, a vertical stick, post, pole or tower casts a shadow exactly along a north-south line.
Since I can’t always rely on finding a convenient vertical stick or pole, I made this “portable North
finder”. It is a crude sundial without the calibrated dial.
My decidedly lo-tech device is built from a scrap piece of galvanized steel sheet about half a metre
long by a quarter of a meter or so. I cut a thin, straight slot up the middle using a grinder with a
thin metal-cutting blade.
The vertical stick/indicator is a straight piece of scrap steel about 400 x 10 x 3mm, held in place
with a pair of homebrewed right-angle aluminium supports (scraps, again) that are riveted to the
base, with a single rivet through the upright. I took a bit of care to set the indicator at exactly 90
degrees to the base plate using a set-square.
Here it is being used for the very first time on the concrete base of my tower. Moments before I
took the photo, at precisely solar noon, I turned the base so that the shadow fell directly along the
slot, then spray-painted the slot with white enamel to leave a line marked on the concrete pad
Here’s the paint mark. I have subsequently scored
the concrete using an angle grinder for a permanent
The single-rivet fixing of the indicator makes a hinge,
with two advantages. Firstly, the device is portable
so I can lend it to friends or take it on field trips
(although a compass is easier!).
Secondly, rather than having to wait for a clear
Winter’s day, I can lower the pointer from vertical to
lengthen the shadow when the sun is high in the sky
in summer. It’s easier to align the shadow with the
slot like this, but any error in the vertical plane of the
pointer will be magnified:
I am well aware that the beamwidth of my HF beams, plus inaccuracies in the rotator direction
indicator, makes this degree of azimuthal precision unnecessary, but designing, building and using
this device was an interesting and fun little project.
Besides which, I can now measure the magnetic declination at home: it’s simply the azimuth
difference between the compass North and true North.
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As well as the Elecraft K2 and K3 radios, I've got various homebrew QRP ‘rigs’ (most are bare
patchboards!) in various states of dis/repair about the place. There’s an OXO somewhere, naturally
, and a TEME from Practically Witless magazine many moons ago.
I’ve built these over the years just for the hell of it. Most of the fun is in building them and after the
thrill of making the first few QSOs, I soon lose interest, except for the K2 and K3 that is. SPRAT,
the G-QRP-Club magazine and Pat Hawker’s Technical Topics column in RadCom were the
inspiration for most of those projects.
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A ham’s workbench
Table, desk, worktop etc. at least a metre square.
Soldering iron or soldering station or at least some sort of safe holder for a hot iron.
Solder - thin multicore electronics solder, not the crude chunky stuff that plumbers use.
Small electrical tools - a selection of screwdrivers, wire cutters, pliers, knives etc. used by
A small vice - nothing major like drugs.
Bits to build or repair, plus spare parts from the junk box (some of which were mysteriously
left-over from previous projects).
<Ahem> A junk box. A box of stuff that will ‘come in handy one day’. Hide it if you must.
Spare time to build or repair bits. This is my most rare and valuable resource ...
Test equipment - a decent multimeter at least and ideally a scope, power meter and dummy
Tea. Hot. Lashings of it.
Remove other stuff from the workbench. All workbenches have a strange physical attraction
for stuff. A box to
dump store it in may help (see part #7).
Drink the tea.
Get bits ready to build or repair.
Drink more tea.
Find useful bits in the junk box.
Remove extraneous stuff that has already started to accumulate.
Build or repair things.
Celebrate with more tea, even if cold.
Put remaining useful spare bits away in the junk box.
Leave stuff all over the place ready for step 1 on the next project.
By the way, I’m told you really need only two tools in life: WD-40 and duct tape. If it doesn't move
and it should, use WD-40 (or CRC in these parts). If it moves and shouldn't, use duct tape. Duct
tape is like The Force: it has a light and a dark side and holds the universe together. It’s well known
that WD-40 was invented to stop the multi-billion-dollar US space shuttle from squeaking, and
strongly suspected that the ultimate demise of the space shuttle mission was caused by squeaks
that exceeded the engineering capabilities of WD-40.
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Being a scientist by training,
I like to keep a little lab
notebook or journal with
details of the ‘experiments’
that I conduct in connection
with amateur radio. The
notebook has proven
invaluable over the years,
especially so as my memory
weakens, and so I
commend this simple idea to
all hams. Here are some
extracts from my
notebooks to show you
how they work for me.
The circuit diagram here
shows how I connected the
PC to the keying transistor
inside my homebrew keyer
rather than fit another
transistor inside the D
-connector. It seemed like a
good idea at the time (1989
The pages below refer to
contests I entered in 1990.
The photo of a 2m
masthead preamp takes
me right back to that VHF Field Day when we lost a good hour right at the start of the contest
thanks to a wayward blob of solder being pointed at by Chris or Ian. Grrr. We stopped using
masthead preamps after that incident.
Starting at the rear of the notebook and
working forward until the book is full (like I
said, I’m a scientist!), I record the
contests I’ve entered year-by-year. Here’s
the page for 1988 when I started keeping
the notebooks. I was a student in
Leicester Uni at the time and belonged to
the Leicester Radio Society.
My second radio notebook is nearly full
now, giving an average of ten years’
experimentation per notebook. I guess
the records set by Marconi, Hertz and
other genuine radio experimenters are
"Be a collector of good ideas,
but don't trust your memory.
The best collecting place for
all of the ideas and
comes your way
is your journal."
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“The excitement of learning separates youth from old age. As long as you are learning, you’re not old.”
Rosalyn Sussman Yalow