MFJ Enterprises 8100w World Band Receiver Manual

							MFJ-8100                                                                 
World Band Receiver 
 
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Throughout this instruction manual, we use plain English as 
much as possible.  But theres no way around using common 
electronics terms and abbreviations where appropriate.  We 
simply try to avoid jargon that is unnecessary.  The 
following mini-glossary was compiled as a help to beginners 
work with this unit.  Our descriptions are NOT intended to be 
complete definitions. 
 
For a very clear and economical explanation of electronics 
parts and how they work, see Getting Started in Electronics 
by Forrest Mims III, No. 276-5003, at any Radio Shack store. 
 
Alignment -  One-time adjustment of internal controls in a 
radio circuit.  (See also: Trimmer) 
 
AM -   Amplitude Modulation 
 
Band -   a related group of frequencies 
 
Board -  short for printed circuit board or circuit board. 
Bridge, Solder - the unintentional joining of two or 
more points on the solder-side of a printed circuit 
board. 
 
Carrier -   the steady tone or whistle that is the 
foundation of an AM or FM voice signal.  In most 
receivers, the carrier is not even heard, because 
regeneration or a BFO or direct-conversion is 
required to convert the carrier energy into an 
audible tone. 
 
CW -   Continuous Wave - refers to Morse Code signals 
 
DC -   direct current (example: battery voltage in contrast 
to household AC from the wall outlet.)  DC sometimes 
refers to direct conversion receivers: see below. 
 
Detector -   the section of any radio that changes radio 
energy into audio energy intended for listening. 
 
Direct Conversion - a popular type of simple receiver for CW-
SSB which needs no regeneration control but which 
does not permit pleasant listening to AM shortwave 
broadcasts, because the carrier (see above) as well 
as the voice modulation can be heard. 
  
						

							MFJ-8100                                                                 
World Band Receiver 
 
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Electrolytic   (capacitor) - a capacitor containing an acid 
or salt paste (electrolyte) and is generally 
polarized with a positive and negative side.  
Correct polarity MUST be observed when installing 
electrolytic capacitors. 
 
FET -   Field Effect Transistor 
Ground -  Refers to all points and surfaces in an electronic 
device which are connected to the -DC side of the 
power supply or battery.  A ground plane of a 
circuit board is the large area of copper plating 
that is common to ground.  Earth ground refers to 
water pipes or metal grounding rods in direct 
contact with Mother Earth! 
 
IC,   Integrated Circuit - A tiny plastic rectangular 
block with 6, 8, 14 or more pins, containing a 
silicon chip which provides the equivalent of 
dozens or hundreds of individual transistors and 
resistors. 
 
K -   abbreviation for 1000 ohms.  (10K = 10,000 ohms). 
 
KHz -   KiloHertz 
 
MHz -   MegaHertz 
 
Inductor -   A coil or loop of wire used in electronic 
circuits Oscillator - see Regeneration 
 
pF. -   picofarad, a tiny unit of capacitance. 
 
megohm -  one million ohms 
 
Regeneration, Regenerative - a method of boosting the 
performance of a simple detector by feeding the 
detected signal back to the input of the detector 
for further amplifying. This oscillation process 
must be controlled carefully through the use of a 
regeneration control. 
 
RF -   Radio Frequency Energy, in contrast to audio or DC. 
 
RTTY -   Radio Teletype 
 
SSB,   Single Sideband - a method of voice transmission 
which eliminates the carrier (whistle) which you  
						

							MFJ-8100                                                                 
World Band Receiver 
 
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hear in an AM broadcast if the Regeneration control 
is turned too far to the right. 
 
Tolerance -   the manufacturing accuracy for electronic (and 
other) parts.  Tolerance ranges from 20% down to 
better than 1% of the value marked on the part.   
 
Toroid -  a type of coil consisting of wire wrapped around a 
donut-shaped form, such as L5 in this receiver. 
 
Trimmer - a miniaturized variable resistor or capacitor used 
for occasional circuit adjustments. 
 
uF. -   micro farad, the usual unit of capacitance. 
 
uH. -   micro henry, a unit of inductance. 
 
Sample SWL Logging Page 
 
Date 
UTC/GMT Name and 
Location of 
Broadcast 
service Call 
sign Band or 
Frequenc
y  Signal 
Qualit
y
Listening 
Notes, QSL 
info, etc 
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
        
						

							MFJ-8100                                                                 
World Band Receiver 
 
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							MFJ-8100                                                                 
World Band Receiver 
 
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MFJ-8100 Parts List 
 
Component Number  Value/Description  MFJ Part  
No. 
C1          Air-variable, 
tuning  204-5050 
C2,C4, C10, C11, 
C15     .1 uF.   200-2017 
C3          47 pF.   205-0021 
C5          5-30 pF. trimmer  204-0013 
C6          33 pF.  200-2016 
C7, C8, C21, C28  .01ufd.  200-2015 
C9, C17         .0033 polystyrene  201-0008 
C12         22  uF.
electrolytic 203-0013 
C13         100  uF.
electrolytic 203-0015 
C14         10  uF.
electrolytic 203-0012 
C16         75 pF.  200-1011 
C18         1 uF. electrolytic  203-0006 
C19         470  uF
electrolytic 203-0004 
CR1         LED  320-0001 
IC1         LM386 audio amp  311-0386 
L1          10 uH   401-0102 
L2          3.3 uH  401-0045 
L3          1 uH  401-0037 
L4          .47 uH  401-0015 
L5          T-52-2 toroid, 8T  403-1003 
Q1-Q3          J310 FET    305-6310 
R1          10K pot,   162-4100-1 
R2          250  ohm  pot,
volume  162-2250-1 
R3-R5, R8         10K  100-4100 
R6, R9          1K  100-3100 
R7          1 M  100-6100 
R11         22 ohms    100-1220 
R12         15 ohms    100-1150 
R13         2.2K   100-3220 
R17         10 ohm  100-1100 
R19         10K trimmer,  130-4100  
						

							MFJ-8100                                                                 
World Band Receiver 
 
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R20         100K trimmer,    130-5100 
J1          Antenna connector  06-0003 
J2, J2          Stereo 1/8 jack  601-4010 
SW1         5-position switch   500-0024 
SW2         push switch   504-0022 
 
Note: C 20, C 22-27, R10, R14-16, R 18 are not used. 
 
PC-Board View
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
						

							MFJ-8100                                                                 
World Band Receiver 
 
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Schematic Diagram