User manual

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Shipping: 13737 SE 26
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Toll Free: 800-259-7331 * Phone: [phone] * Fax: [phone]
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41
When operating in MANUAL mode, the MAC-200 ignores the
antenna setting, but the antenna tuner continues to function. Tuner
settings will be stored and recalled from memory without changing
the antenna selection setting. This may cause retuning when going
back to the AUTO mode since the antenna and the tuning settings
may no loner match.
Tuner settings are stored in predefined ‘bins’ across the range of
the tuner. The width of each bin varies with frequency, but
averages approximately 170 kHz per bin, with more bins at lower
frequencies and fewer, wider bins at higher frequencies. Retuning
may occur when working at opposite ends of a bin if the change in
feed point impedance with frequency is particularly high. This will
be particularly common with High-Q, narrow bandwidth antennas.
4.5 Front Panel Reset-Lock operation
The LOCK button when engaged (the small LED next to the
button is on), tells the coupler to ignore all instructions to tune. It
will not react to a change in any sensor. The RESET function,
when pressed, resets all internal relays to a position that connects
the transceiver directly to the antenna.
Mailing: PO Box 3526, Bellevue, WA. 98009
Shipping: 13737 SE 26
th
St. Bellevue, WA. 98005
Toll Free: 800-259-7331 * Phone: [phone] * Fax: [phone]
www.sgcworld.com * Email: [e-mail]
42
4.6 Do-it-Yourself Light Bulb Test
Any time that a transmitter is used, it must be outputting into a
load. A load is anything that the output power can be pumped into.
If the transmitter is operated without any sort of load connected,
the final amplifier stage could become severely damaged. The
problem is that you should never test a transmitter on the air for the
first time, if you are unsure about how to operate it, and if you are
unsure whether it is working properly. You could create harmful
interference to other stations.
To test transmitters without actually operating into an antenna,
dummy loads were created. A dummy load is a load that will
dissipate the energy from the transmitter instead of emanating it
into the ionosphere. Nearly all commercial dummy loads are large
oil-filled cans. These dummy loads change the transmitted energy
into heat, which is absorbed by the oil. Because different
transmitters output different amounts of power, different sizes of
dummy loads must be used. Dummy loads for typical amateur
powers (<500 watts) are relatively inexpensive and are readily
available.
Unfortunately, when you use a can-type dummy load, you can’t
see “what’s happening” with your transmitter. In this case, you can
use a light-bulb dummy load to test your transmitter. Here, the
light bulb is directly connected to the output of the transmitter and
it dissipates the RF energy as light. The light bulb dummy load is
more useful than the oil-can type because you can guess how much