7 Watt VHF Linear Amplifier


If this kit is built correctly, it will amplify a signal of 1/5 to 3/4 watt up
to about 7 watts of output from 80 to over 120 Mhz. Actual output depends on
voltage, load or antenna (Note: Connecting this to an antenna may be illegal in
some countries), input signal and, of course, construction techniques. This kit
will also work best if it is mounted in a metal enclosure.


Parts List


Q1 	 	2SC1971 NPN Transistor
VC1, VC2, VC3	2 to 80 pf variable capacitor
C1, C3		.001 ufd monolithic (axial) capacitors
C2, C3		.1 ufd monolithic (axial) capacitors
C5		Electrolytic capacitor (10 to 100uf)
C6		27-33 pf disc capacitor
R1		47 ohm resistor
FB		ferrite bead
L1, L2		2 turn coil
L3		6 turn coil
L4		7 turn coil
PC board


Assembly Instructions


The transistor, Q1, will need to be mounted to a heat sink. The chassis of a 
metal box is a convenient and effective heat sink. Be sure to install it with 
the numbers and letters facing the PC board. Failure to mount this part 
correctly or inadequate heat sinking will destroy the transistor. Heat sink 
grease is recommended. You need not worry about grounding out the transistor, 
the case and tab are connected to the emitter, which is also the ground.


Tuning


Tune your transmitter to the desired frequency. Place the amplifier in series 
with the transmitter. You can of course, use any type connector you choose, or
you can wire it directly, depending on personal preference. Connect a RF power
meter with a proper load attached to the output of the amplifier. Apply 12 to
15 volts to the power leads. Notice the reading on the meter. Adjust VC1 for 
the highest reading. Do the same for VC2, and VC3. You should get between 6 and
7 watts of output. Even though you can adjust the amplifier to almost 10 watts,
doing so for any extended amount of time will most likely fry your Q1 
transistor!


Replacement Parts


Many of these parts are available at your local Radio Shack or other supply 
store at a nominal cost. You will probably have a difficult time locating the
trimmers, (VC1,2,3 and 4) and the transistor (Q1) is hard to find as well.
If you receive a defective part, please send it back for a free replacement.
Please note, our technicians can tell if a part is defective or was burned out 
by misuse! Don't be afraid to say you screwed up. We all do that from time to
time. Most of these parts are very resonably priced, and the ones that aren't
only cost a couple grand! Hopefully, those aren't the ones that got fried! 
Actually, none of the parts cost more that $6.00.... so cheer up!