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Use an Antenna Tuner
Get maximum power to
your antenna by learning how to hook up
and use a tunner to
properly "trick" your rig!
Yes, "TRICK" YOUR
RIG!So now that you have a better understanding
of what an antenna "tuner" actually does, let's hook one up in a
typical HF station.
WHAT IS AN ANTENNA
You have to learn how to
hook them up to your tranceiver properly and tune them correctly to
make your radio "think" that it is
feeding it's signal into a "perfect or near perfect 50 ohm laod
called your antenna!
tuner, (transmatch), doesn't really TUNE your antenna OR ANY PART OF
What an antenna tuner or transmatch does do, however, is
transform the impedance at the antenna feed output at the radio to a
value that your transceiver can handle, (typically 50 Ohms).
thinking about antenna tuners and SWR, it's important to remember
that the tuner has no effect whatsoever
on the SWR between itself and the antenna.
It's the SWR
between the transmitter and the tuner that is changed with the tuner
terms, all a tuner does is act as a kind of adjustable impedance
transformer between the radio and the antenna. It takes whatever
impedance the antenna system presents, up to the design limits of
the tuner, and attempts to convert it back to 50 Ohms--or something
reasonably close to that value for the transceiver. When the
transceiver "sees" a 50 Ohm impedance, it is able to load or produce
it's maximum designed RF output into the system because it is
designed to operate into a 50 ohm
rig "thinks" it's seeing a 50 ohm antenna on it's
That power is transferred through the antenna tuner, to
the feed line and, ultimately, to the antenna--minus any losses incurred
along the way.
If you have high loses and a poor excuse
for an antenna, you will have a poor excuse for a good signal no
matter how well your tuner "tricks" your radio.
Much of the power
will be lost as heat in the tuner and very little will get to the
These losses are the reason that the highest efficiency
feed-line for each individual case is desirable and why some
amateurs use ladder line on HF, which has the least loss per foot,
which means maximum power at the input terminals of the
HOW TO HOOK UP AND
In the block diagram below we have
typical Hf station setup consisting of, from lert to
An HF Transceiver
A Linear or power amp
Swr/Watt Meter combo
The Antenna Tuner
The MOST IMPORTANT PART......THE
Take a look at the block diagram
above and notice where the antenna tuner and SWR meter are in
relation to the flow of the RF signal coming from the transceiver.
(Note that the rf is actually flowing in both directions and not
just toward the antenna).
PLEASE DISREGARD THE LINEAR AND
LOW PASS FILTER FOR THE MOMENT! (Your station may not use
You will notice that.... first, from left to right, you
have the transceiver, Swr/watt meter, ANTENNA TUNER and then the
antenna on the output.
The rf moves from the transceiver to the
SWR/WATT meter, then finally thru the "tuner" and out to the
You just learned
how to hook it all up! Just remember that our goal is to make the
transceiver think all is well, and in order to "read" the SWR and
Power out pertaining to "all is well"......at the radio's
output....the swr meter must be between the
radio and the tuner. NOT ON THE ANTENNA
Now Let's learn how to "tune" that
Most antenna tuners have an
inductance rotary switch and two capacitors. (refer to photo at top
of page) The capacitors are often labeled ANTENNA and TRANSMITTER.
In some antenna tuners the inductance switch is replaced with a
continuously variable inductance, popularly known as a roller
assume you're using a tuner with an inductance switch, because they
are the most common.
SHOCK HAZARD! NEVER TRANSMIT WITH THE TUNER
COVER OFF AS IN THE NEXT STEP!
TURN OFF THE POWER TO THE
Place both capacitor controls at their mid-range positions.
Don't trust the knob markers if this is your first experience with
the tuner! If you are comfortable with the next procedure,
remove the cover of the tuner and turn the knobs until the moving
capacitor plates are only half meshed with the stationary plates. If
the knobs are pointing to half scale with the reference markings on
the knobs and front cover, consider yourself lucky.
loosen their Allen screws and rotate the knobs so that they point to
Re-tighten the knobs, replace the tuner cover and you're ready to go.
Turn the radio on and tune
receiver to an un-used frequency on the band you desire, listen for a few
seconds, with the antenna and transmitter controls at mid
scale, move the inductance switch to each of it's positions until
you hear the loudest noise or signals coming into your radio. Then,
rotate the antenna and transmitter controls until you get to the
absolutely loudest noise or signal level on the radio. All three of
these controls interact with each other so practice on several bands
to get the "feel" of the procedure.
Select your final band of
operation and repeat the procedure above. When noise peaks out using
your ears and the S meter, your tuner settings should be very close
for final operation.With your rig set to low power monitor the
frequency to assure that it is not in use, send your ID then
transmit a continuous carrier while you tweak the antenna and
transmitter controls for the lowest reflected power reading with the
highest output power as read on the Swr/Watt meter. You may find
that you have to vary the position of the inductance switch a
position or two either way to get your best match.
Play it safe
and un-key before turning the inductor switch...un-key
first....turn the switch...key up....repeat as needed until
lowest SWR and maximum output. Be gentle to your radio; keep the
key-down periods as short as possible. Depending on the impedance at
the antenna input (and the overall design of the tuner) you may not
be able to obtain a flat 1:1 SWR on all frequencies and
Also important to remember is that your Swr will change,
go up, as you tune further away from the frequency you used to
"trick" your radio! So re-check and re-tune as needed as you move
around the band.
You can get an idea of your SWR bandwidth by
starting with your original frequency, and using the procedures
above withlow power, (don't move any knobs or switches after best
setting)....sweep or tune your VFO up and down the band while
watching the SWR readings and note the frequency where the SWR
reaches 2:1 at the higest and lowest frequency. Stop
your on 40 meters at say...7.262mhz as your starting point, and your
SWR is 2:1 at 7.292mhz and the highest swr going the other way is
2:1 at 7.259mhz, then your "safe tuning range" without retuning the
antenna tuner would be about 60khz.
Keep in mind to use very low
power and ID because your signal may be heard for a split second as
you tune across the band! When that transmit key is down, someone
somewhere can hear you. Even a dummy load gets out
Remember your "TRICKING" your way around a good
So what kind of tuner
should I buy?
Click on the ad below to
see the latest ARRL Book "A Guide to Antenna Tuners"
Loaded with information for choosing the
right tuner for your ham radio station!
New! from the
The Guide to Antenna Tuners!
A must have for all
hams who need more information!
there is no "tricking" involved anywhere and we were playing
with words here like "tricking, fooling", etc.
It is useful to
employ a matching device, the antenna tuner, between the transmitter
and the antenna feeder when antennas with complex impedances are
used..... so the transmitter will "see" a 50 -52 ohm load even
though a significant mismatch is present at the antenna feed
point. The tuner, matchbox or transmatch as it is sometimes
called, will not correct the actual SWR condition
on the feed line OR antenna, but it will resonate the antenna system
as a whole that the radio "sees" on
it's output and allows the transmitter to
deliver as much power to the antenna system as possible
within the design parameters of the tuner. The transmitter now can
produce it's rated power out to the tuner in the
hopes that the tuner can do it's job and get most of that power into
the antenna system with some efficiency.
line: Your transmitter will not
know that you are trying to "load up" those old rusty bed springs or
that poor excuse for an antenna! Just because you're now seeing that "magic" 1 to 1 VSWR
reading on the meter does not mean you have changed the design of
those old rusty bed springs or whatever you're trying to us as
The more efficient your antenna system.....the better!
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