skema booster tv

Troubleshooting:
The fact that there are two independent pre-amplifiers in the AA-7 makes faults easier to diagnose than with many other devices. If a problem occurs, only at one setting of S1, concentrate on that part of the circuit. If the problem is common to both settings, the components and the connections common to both preamps should be checked. Make sure the jumper wires are in place!
There are other characteristics or phenomena associated with preamplifiers and active antennas that does not mean that your circuit is malfunctioning. For example, if you have strong AC hum in the HF setting, the antenna is too close to an AC cord or powerline. HF signals may be clearer at the VHF/UHF setting than in the HF setting. Why? Although either pram may be used for HF, the signal strength will be greater with the VHF/UHF pram. However, the HF signal-to-noise ration is better with the dual-gate-MOSFET-based pram. Try both and use the best for your particular receiver conditions.
Some portable receivers not enclosed in metal cases may break into oscillation when connected to any RF preamplifier. Try reducing the AA-7's gain and make sure that good grounds are provided with the interconnecting coax cables. A preamplifier will intensify any problems due to poor receiver design: overloading, images, or any other problems with selectivity and image rejection.


 

Parts List and other components:

Semiconductors:

Q1 = MFE201, SK3991, 3N201 (R2 not needed), or NTE454 N-Channel, dual-gate MOSFET, TO-72 (see text)
Q2 = 2SC2570, NTE107. Silicon RF IF/Amp, NPN transistor (see text)
     Note: If you use the NTE107 as a replacement, make sure to insert it correctly 
     into the pcb.  The orientation is different than as shown on the parts layout
     diagram. (e-c-b seen front view for NTE107).  See this Data Sheet


Resistors:
All Resistors are 5%, 1/4-watt
   R1 = 1 Mega Ohm
   R2 = 220K
R3,R6 = 100K
   R4 = 100 ohm
   R5 = 10K potentiometer (pc mount)

Capacitors:
C1,C2,C5,C6 = 0.01uF, ceramic disc
         C3 = 100pF ceramic disc
         C4 = 4.7 to 10uF, 16WVDC, radial lead electrolytic

Additional Parts & Materials:  
   B1 = 9-volt alkaline battery
S1,S2 = DPDT PC mount pushbutton switch
J1,J2 = PC mount RCA jack
 ANT1 = Telescoping whip antenna (screw mount)
 MISC = PCB materials, enclosure, enclosure, battery holder and connector, 
        wire, solder, etc.