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AN758 300 WATT HF AMPLIFIER
The AN758 HF amplifier is a push-pull linear amplifier for
300 watts of PEP or CW output power across the 2 to 30 MHZ band. One of
Motorola's new high-power transistors developed for single-sideband, the MRF429,
is used in this amplifier design. The AN758 operates from a 50 Vdc power supply.
The amplifier employs a push-pull design for low, even harmonic distortion. This
harmonic distortion and the 50 Vdc supply voltage make the output impedance
matching easier for 50-Ohm interface and permits the use of efficient 1:1 and
4:1 broadband transformers. Modern design includes integrated circuit bias
regulators and the use of ceramic chip capacitors throughout the RF section,
making the units easily reproducible.
SPECIFICATIONS:
| Frequency Range |
2 to 30 MHZ |
| RF Input Power |
15-18 watts (typical) |
| RF Output Power |
300 watts |
| DC Input Voltage |
50 Vdc |
| DC Input Current |
14 amps (typical) |
| R1, R2 - 2 x 3.9 Ohm, 1/2 W |
C1, C2 - 5600 pF Ceramic Chip |
D1 - See Text |
| R3, R4 - 2 x 6.8 Ohm, 1/2 W |
C3 - 56 pF Ceramic Chip |
D2 - 1N5361 - 1N5366 (See
Text) |
| R5 - 1 Ohm, 1/2 W |
C4 - 470 pF Ceramic Chip |
Q1. Q2 - MRF428 |
| R6 - 1k Ohm, 1/2 W |
C5 - 560 pF Ceramic Chip |
Q3 - 2N5991 |
| R7 - 100 Ohm, 5 W |
C6 - 75 pF Ceramic Chip |
L1, L2 - Ferroxcube VK200
19/4B |
| R8 - 18k Ohm, 1/2 W |
C7, C8 - 0.1 uF Ceramic Chip |
L3, L4 - 6 Ferrite Beads each |
| R9 - 8.2k Ohm, 1/2 W |
C9, C10 - 0.33 uF Ceramic
Chip |
Ferroxcube 56 590 65/3B |
| R10 - 1k Trimpot |
C11 - 10 uF, 150 V |
T1 - 9:1 RF Transformer |
| R11 - Not Used |
C12 - 1000 pF Ceramic Chip |
T2 - 7 turns of bifilar AWG #
20 |
| R12 - 1k Ohm, 1/2 W |
C13 - 1000 uF, 3 V |
T3 - 14 turns of 25 Ohm mini
coaxial cable wound each toroid |
Printed Circuit Boards
and Components Available
The above is a summary description of
an HF amplifier described in the MOTOROLA Engineering Bulletins and Application
Notes. These Engineering Bulletins and Application Notes may be obtained from
your local MOTOROLA office or can be found in the MOTOROLA RF DEVICE DATA
MANUAL. These amplifiers have been designed and tested by engineers at Motorola.
COMPONENT
SETS FOR AN758
| Chip Capacitor Set |
$ 10.95 |
| 1ea. |
56pf Ceramic Chip Cap. |
| 1ea. |
75pf ATC Chip Cap. |
| 1ea. |
470pf Ceramic Chip Cap. |
| 1ea. |
560pf Ceramic Chip Cap. |
| 2ea. |
5600pf Ceramic Chip Cap. |
| 2ea. |
.1uf Ceramic Chip Cap. |
| 2ea. |
.33uf Ceramic Chip Cap. |
| Discrete Cap Set |
$ 1.50 |
| 1ea. |
.001uf 1Kv Ceramic Disc Cap. |
| 1ea. |
10uf 100 Vdc Electrolytic Cap. |
| 1ea. |
1000uf 10 Vdc Electrolytic Cap. |
| Resistor Set |
$ 4.45 |
| 1ea. |
1 ohm 1/2W Resistor |
| 4ea. |
3.9 ohm 1/2W Resistor |
| 4ea. |
6.8 ohm 1/2W Resistor |
| 2ea. |
1K ohm 1/2W Resistor |
| 1ea. |
8.2K ohm 1/2W Resistor |
| 1ea. |
18K ohm 1/2W Resistor |
| 1ea. |
100 ohm 5W W.W. Resistor |
| 1ea. |
1K ohm Trim Variable Resistor |
| Semiconductor Set |
$ 6.75 |
| 1ea. |
1N5363A Diode |
| 1ea. |
2N5192 Transistor |
| 1ea. |
2N6488 Transistor (with mounting hardware) (2N5991
replacement) |
| 1ea. |
MC1723CG Voltage Regulator |
| Ferrite Set |
$ 4.80 |
| 12ea. |
56-590-65-3B Ferrite Beads |
| 2ea. |
VK200 20/4B Ferrite Choke |
| RF-T1 RF Transformer Assembly
(wound) |
$ 4.95 |
| RF-T2 Toroid Core (wound) |
$ 2.25 |
| RF-T3B Toroid Cores (2) includes
40 inches of 25 ohm coax |
$ 11.90 |
| Printed Circuit Board (3 5/16"W x
5 3/4"L) |
$ 14.00 |
| MRF429MP Matched Transistor Pair |
$
96.00 |
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This Page was last
updated April 17, 2007
