LPA1
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Welcome to the LPA Power Booster Amplifier
Thank you for purchasing the LPA1 Power Booster Amplifier. The LPA -1 is
a state of the art amplifier for almost any low power transmitter. With a fre-
quency range from 100Khz to almost 1Ghz, it is no wonder that it is so ver-
satile. And with an incredible gain of up to 38.5dB (7079 times the input
power) at 10 Mhz, you can finally be heard over all of the noise and interfer-
ence on many bands. For very low power ham radio QRP equipment, VCR
“rabbits,” and virtually anything else that you can hook it to, you will notice a
big difference in the signal distance and clarity. A gain of 38.5dB means that
only 125 micro watts will get you 1 watt of crystal clear power!
You’ll notice that the PC board included with your kit contains plating on both
sides of the board. This topside ground “plane” is necessary to create the
proper RF impedance in the traces run on the bottom side of the board. We
have also used the latest in trouble free amplifiers, the Mini Circuits MAV3
IC, to provide crystal clear linear amplification.
NOTE TO NEWCOMERS: If you are a first time kit builder, you may find this
manual easier to understand than you may have expected. Each part in the
kit is checked off as you go, while a detailed description of each part is given.
If you are to follow each step in the manual in order, and practice good sol-
dering and kit building skills, the kit is next to fail-safe.
Circuit description
Your Power Booster Amplifier consists of a simple circuit in terms of compo-
nents. Since the kit operates at frequencies as high as 1Ghz, your board has
been specially engineered for proper impedance matching. As signals go up
in frequency, they behave very differently than you might expect. Without a
properly designed board, the signal may actually begin to reflect throughout
the circuit. These reflections may cause a substantial loss of gain in the cir-
cuit. To help eliminate this effect, your board has been designed using a
process called micro-strip design. This feature is what allows you to get rela-
tively high gain from your LPA1 at very high frequencies. Throughout the
construction of this kit, it is extremely important to make sure that all leads on
components are kept as short as possible. If you do not make an attempt to
make the leads as short as possible, you may not find the output power or
gain as we have designed it.
The main components of the circuit are the RF amplifier and Q2, an MRF581
power transistor. The MAV3 is a state of the art amplifier specially designed
to work in a wide range of radio frequencies. The MAV3 amplifies the signal,
but does not have the power output capabilities to push out such high power.
For this reason, Q2 is placed in the circuit. Q2 amplifies the signal a bit more,
and is capable of generating a large amount of power out of the circuit.
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