75+ WATT 432 MHZ LINEAR AMPLIFIER

The following information details an all solid state linear amplifier for 432 that is easy to build using standard components. It is possible to get 100 watts out of this amplifier but heatsinking and output matching is critical. If you decide to build this amp, gather all the parts required and then take you time building it. Take great care to use minimum amounts of heat for all soldered connections. Below is the schematic.

Here is the parts list for the amplifier.

T1 & T2	Balun, unbalanced RG-58, 2.5" long
R1	1K 1/2 watt
R2 & R3	10 ohm 1/2 watt
R4 & R5	5.6 ohm 1 watt
R6	2.7 ohm 1/4 watt
Z1 & Z3	Microstrip 200 mils X 1.8" long
Z2 & Z4	Microstrip 200 mils X 300 mils long
Z5 & Z6	Microstrip 150 mils X 300 mils long
Z7 & Z8	Microstrip 150 mils X 1.4 " long
RFC1 & RFC4	Ferroxcube bead 56-590-65-3B
RFC2 & RFC 3	.15 uh molded choke
RFC5 & RFC6	1 turn #20, 5/16" diameter
RFC7 & RFC8	VK200 20/4B
C1,3,4,5,7,8,11,15	Underwood 40 pf
C12 & C16	Underwood 25 pf
C13, 14, 22, 23	Underwood 15 pf
C9, 10, 18, 20	1 uf tantalum
C21 & C24	Underwood 10 pf
C2 & C6	Arco 403 trimmer
C17 & C19	1000 pf feedthrough
C25 & C26	.1 uf caramic disk
L1 & L3	#14 wire 1.2" long
L2	#14 wire .6" long
PC Board	G10, eR = 5. .062 thick (see note)
Q1	2N5192
Q2	2N5194
Q3 & Q4	MRF309
D1	1N4001 or equal

NOTE on PC Board: Availabel from Far Circuits for a nominal charge.

Once the amplifier has been completed, tune up is fairly simple. Having a regulated and current limited power supply will make tune up easier and less risky. It is easy to burn out a transistor if it is allowed to draw too much current. Following the construction directions closely will result in a stable amplifier that will work for many years. Leaving leads too long might introduce oscillations that can quickly destroy the amplifier. Remember, you are working at UHF frequencies and the shortest possible lead lengths are a must.

Take your time and have fun with this construction project.

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