Photo A.
Greg Wilson, KCØADT, making contacts from the summit of Mount Democrat
during the 2001 Colorado 14er Event. Note the use of the “tape measure”
Yagi antenna. (Photo courtesy Isaac Wilson) |
Low-power operating is not just for HF! KØNR shows
us how QRP and VHF can work very welll together, especially during
contests.
By Bob
Witte, KØNR |
|
Take a look at any ham radio magazine or surf
around on the Internet and you’ll find that many hams are active in very
low-power operation. This is commonly known as QRP, defined as having an
output power of 5 watts or less. 1 While most of the QRP activity is on
the high-frequency bands (below 30 MHz), this article focuses on how QRP
concepts also apply on the VHF and higher frequencies.
QRP Operating
The classic QRP station consists of a small, low-power HF transceiver
feeding a basic wire antenna. Often the transceiver is CW-only, because CW
is the most popular QRP mode. SSB is also used for QRP, but the improved
efficiency of CW is desirable when operating low power.
Low transmit power means that the transceiver can be operated using
batteries as the power source, making the whole operation portable and
independent of AC power. Of course, you don’t have to use battery power
for QRP. Sometimes “big gun” stations with huge antennas and kilowatt
amplifiers choose to go QRP by turning down the output power.
The QRP Mindset
QRP is more than just low power. Low power is where it all starts, but
there is a different mindset that comes with QRP. QRP is a self-imposed
challenge, one which involves doing more with less. With less output
power, there is a greater emphasis on operator skill.
The option of battery power means that QRP operation can be very portable,
which enables operation from remote locations. Many QRP enthusiasts
combine their radio activities with camping, backpacking, canoeing, and
other outdoor activities.
QRP also lends itself to experimentation and radio construction. A number
of kits are available for simple QRP HF transceivers, many of which are
CW-only rigs. Again, the emphasis is on getting the best results out of
basic equipment.
To sum it all up, the QRP mindset is that the easiest way is not always
the best way. Making radio contacts and working DX with low power is a
challenge, which makes the results that much more satisfying.
Weak-Signal VHF Operation
In contrast with the QRP world, most weak-signal VHF operation involves
using high power levels. Often a new weak-signal operator starts out with
50 watts or so of RF output and soon begins thinking about an amplifier to
boost the signal. I’ve always thought it somewhat ironic that we call this
“weak-signal” operation when 1-KW stations with large antenna arrays are
so common. Most weak-signal VHF work is “big signal” at the transmit end.
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Operating VHF QRP Portable
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