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AN779H 20 WATT HF DRIVER AMPLIFIER

The AN779H driver amplifier employs the MHW591 hybrid module to drive a pair of larger devices which can be operated Class A or AB, depending on the requirements. Transistors such as MRF449 and MRF455 are recommended for Class A and MRF433 for Class AB operation. A 24-28 volt version with MHW592 and a pair of MRF401s was designed for Class AB. For Class A, the power parts should b e replaced with MRF426s. The amplifier delivers a power output of 20 watts PEP with a gain of 55 dB using inexpensive components throughout. The RF power transistors are extremely tolerant to overdrive and load mismatches. The MHW591 is employed as the predriver in this unit and was developed for low-level SSB driver applications from 1.0 MHz to 250 MHz. The AN779H amplifier was designed to serve as a 1.6 to 30 MHz broadband SSB driver.

 

SPECIFICATIONS:wpe1B.jpg (16995 bytes)
Frequency Range 1.6 to 30 MHz
RF Power Gain 55 dB (typical)
RF Power Input 0.10 Milliwatt (typical)
RF Power Output 20 Watts
DC Input Voltage 12.5 Volts (28 Volt Version Available)
DC Input Current 5 amps (typical)

 

 

wpe1C.jpg (16853 bytes)

 
 

12 Volt Version

  
R1 - 1K Ohm Trimpot C1, C2, C5, C6, C7 - 0.01 uF Chip L6, L7 - 0.1 uH Molded Choke
R2 - 1K Ohm, 1/4 W C3, C4 - 1800 pF Chip Q2, Q3 - MRF433
R3 - Optional C8 - 10 uF/35 V Electrolytic H1 - MHW591    (Discontinued)
R4, R5 - 5.6 Ohms, 1/4W L1, L4, L5 - Ferrite Beads (Ferroxcube #56 590 65/3B T1, T2 - 4:1 and 1:4 Impedance Transformers
R6, R7 - 47 Ohms, 1/4 W L2, L3 - 10 uH Molded Choke  

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 AN779H

12 Volt Version
Capacitor Set

$ 2.70
5 ea. .01uf Ceramic Chip Cap.
2 ea. 1800pf Ceramic Chip Cap.
1 ea. 10uf 35 volt Alum. Elec. Cap.

 
Resistor Set

$ 1.75
2 ea. 5.6 ohm 1/4 W Resistor
2 ea. 47 ohm 1/4 W Resistor
1 ea. 1000 ohm 1/4 W Resistor
1 ea. 1000 ohm Trimpot Resistor

 
Semiconductor Set

$ 1.65
2 ea. 1N4001 Diode
1 ea. MJE240 Transistor

 
Ferrite Set

$ 3.20
2 ea. .1 uh Molded Choke
2 ea. 10 uh Molded Choke
7 ea. 56-590-65/3B Ferrite Beads

 
Transformer Set

$ 10.20
1 ea. T1 Input Transformer (wound)
1 ea. T2 Output Transformer (wound)
4 ea. 0.1 inch spacers

 
Printed Circuit Board (2 1/2"W x 3"L)

$ 17.50

 
MRF433MP Matched Pair RF transistors (12 volt)

$ 61.00

 
MRF426MP Matched Pair RF transistor (28 volt)

$ 61.00

 

CA2832C Hybrid RF Module (28 volt) (Substitute for MHW592)

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 Send mail to cci.dayton@pobox.com with questions or comments about this web site.           

 

                This Page was last updated February 07, 2010