MFJ Enterprises 8100w World Band Receiver Manual

							MFJ-8100                                                                 
World Band Receiver 
 
11 
 
With the control turned fully to the left (counter 
clockwise), the receiver is virtually silent.  
Regeneration begins at a certain point as you turn the 
control clockwise.  The exact point varies not only from band 
to band but even as you tune within a given band.  
Regeneration begins as an audible increase in background 
noise followed by a soft hiss.  The hiss, or any signals that 
may be on frequency, increases as you continue to turn 
clockwise.  If you go too far, the signal becomes distorted, 
or the receiver begins to squeal (oscillate). 
 
Always use the LEAST amount of regeneration necessary for 
good reception of a given signal. 
 
As a rule, the best reception of AM shortwave broadcast 
signals occurs just BEFORE full regeneration.  If you hear a 
whistle (carrier) along with an AM signal, turn the control 
back slightly until the carrier disappears. 
 
When there are a number of very strong shortwave AM 
broadcasts in a given band, such as is common in the early 
evening, you will find it possible to tune them in one after 
the other with the regeneration control set way back and 
requiring virtually no adjustment.  In other words, you would 
tune from station to station just as if using any other type 
of shortwave set. 
When the receiver is adjusted for good AM reception, CW 
signals will sound like hisses.  Advancing the regeneration 
control slightly will bring in the familiar beeping 
associated with CW, RTTY (radio teletype) or similar signals. 
 
The regeneration control can also serve as a fine tuning 
control, permitting slight adjustments of CW pitch for the 
most pleasing sound, or best clarity in a SSB voice signal.  
After youve had some practice with using the regeneration 
control, it will become second nature, giving you a sense of 
real control over the performance of your receiver. 
 
TUNING SSB (Single Sideband) VOICE SIGNALS 
SSB signals are all those voice signals which sound like 
Donald Duck unless they are tuned in very exactly.  They have 
no background carrier as do AM broadcast signals. 
  
						

							MFJ-8100                                                                 
World Band Receiver 
 
12 
On modern ham radio transceivers, tuning SSB is made so easy 
by means of internal filters that many licensed ham operators 
are not aware of the basic technique for tuning in SSB 
signals on receivers without such filters. 
 
The first fact to know about any given group of SSB signals 
is whether they are Upper (USB) or Lower (LSB) Sideband.  In 
ham radio communication, LSB is used on 1.8 through 7.3 MHz, 
and USB is used for all higher frequency bands (14, 18, 21, 
28 MHz.) 
 
The best band to practice SSB tuning with your receiver is 
the 75 Meter band, 3.8 to 4.0 MHz, doing so in the evening 
when the signals are strong and plentiful.  Notice that the 
band is spread out on the dial more than are the other 
amateur bands, which permits easier tuning. These are all 
LSB, lower sideband signals. 
 
Think to yourself: for LOWER sideband, tune DOWN. for UPPER 
sideband, tune UP. 
In practice, this means that you would approach the LSB 
signal by tuning from higher frequency (right) to lower 
(left), from higher voice pitch to lower pitch.  Heres how 
to do it step by step: 
 
1.   Pick out a strong, high-pitched Donald Duck voice.  
2.   Turn the tuning knob ever so slightly to the left. 
3.   If the pitch of the voice went DOWN slightly, youre 
heading in the right direction. 
4.   SLOWLY tune left slightly more until the voice is clear. 
 
Reverse this process to tune to UP (to the right) to USB 
signals on the bands above 7 MHz.   
 
The Regeneration Control often can be used to do the last 
touch of fine tuning to bring the voice in clearly.  If 
signals are exceptionally strong, it may be necessary to 
reduce the RF gain level (rear panel). 
 
SSB transmissions are used by embassies and agencies of 
various governments, so you might find interesting voice 
signals on other than ham frequencies.  Check with a 
Shortwave Listener (SWL) or listings in Popular 
Communications Magazine for more details.  
						

							MFJ-8100                                                                 
World Band Receiver 
 
13 
USING & ENJOYING YOUR RECEIVER 
 
To get maximum satisfaction from your new shortwave receiver, 
we encourage you to develop good familiarity with these 
sections of this manual: 
 
  __ Antenna Considerations 
  __ Regeneration Control 
  __ Band Switch and Tuning Ranges 
  __ Audio Notes 
 
However, lets say it all as briefly as possible: 
 
1.   The better the antenna, the better the reception.  In 
general, 20 to 30 feet of wire will give good results. 
2. The use of the Regeneration Control is learned through 
experience.  It controls the sensitivity of the receiver 
and distinguishes between AM broadcasts and CW-SSB. 
3. The tuning ranges are set up so that you can expect to 
find something interesting at any time of day or night. 
Bands A and B are most active in the evenings.  Band C has 
something happening all the time.  Bands D and E assure a 
variety of daytime reception but also can be busy at 
night.   
4. The audio circuit is designed for one or two pairs of 
Walkman stereo headphones or mini speakers.  Other 
speaker options are mentioned in Section XX. 
 
IMPORTANT: The internal 9 volt battery will provide many 
hours of satisfying listening provided that you turn the 
receiver OFF when not in use!  This advice may seem 
ridiculously obvious, but remember that battery replacement 
requires removing and replacing the 8 cabinet screws and that 
leaving the receiver on overnight will indeed run down the 
battery.  If you wish, the battery snap wires can be re-
routed to the battery clamp mounted  outside on the rear 
panel.  Or, the receiver may be powered by larger external 
batteries in the 6 to 12 volt range.  4 to 8 D cells in 
plastic battery holders available from Radio Shack will 
provide months of service.   
 
NOTE: If a DC voltage other than 9 volts is used, 
readjustment of trimmer C5 will be required for 
correct frequency indications. 
  
						

							MFJ-8100                                                                 
World Band Receiver 
 
14 
SETTING UP A USEFUL SHORTWAVE ANTENNA 
The reason why we provided a universal binding post 
antenna connector (plus separate ground connector) is to make 
it as easy and economical for you as possible to try out 
different antenna setups.  By universal, we mean that you 
can insert a banana-style plug OR make various styles of 
connection with a simple bare wire. 
 
Your receiver is so sensitive that even a few feet of wire 
strung indoors will provide reception of stronger signals, 
particularly at night.  20 to 30 feet of wire is much better. 
Therefore, you can count on good reception even if you are 
limited to keeping the antenna indoors as might be required 
in apartment complexes, condos, etc. 
 
Stringing all or part of your antenna outdoors is always 
better. An ideal antenna for this receiver would consist of 
25 to 100 feet of wire outdoors, as high as is safely 
possible.  Such antennas are called random long wires and 
also work fine in most attics.  (Foil-backed insulation or 
metal roofing will reduce the usefulness of an attic as 
antenna space.) 
 
Your antenna can be horizontal, vertical or a combination of 
both. It can be tubing or pipe as well as wire.  The wire can 
be bare or insulated.  It could be something not intended to 
be an antenna such as a gutter, fence, flagpole or metal 
roof.  In fact, radio hams and serious SWLs have 
experimented with thousands of imaginative antenna ideas.   
 
VERY IMPORTANT:  Use care and common sense when putting up 
outdoor antennas.  Be certain that your wires or your ladder 
cannot come into contact with electrical power lines.  You 
can be KILLED
 by accidental contact with power lines. 
 
YOUR RECEIVERS AUDIO CIRCUIT: MANY WAYS TO LISTEN IN! 
The LM386 audio amplifier IC circuit is designed to provide 
ample volume to not one but TWO headphone jacks.  We used 
stereo jacks because todays economical personal music 
headphones are as inexpensive as were the bulky basic 
headphones of yesteryear.  Your receiver provides two 
headphone jacks to make it very easy for two people to listen 
together.  
  
						

							MFJ-8100                                                                 
World Band Receiver 
 
15 
The amplifier circuit provides sufficient output for moderate 
speaker volume.  Miniature speaker systems designed for 
Walkman and similar personal stereo devices will plug 
right into J2 or J3 and work very well.  However, please 
remember that the amplifier is specifically designed for 
headphone operation.  If you prefer room-level speaker volume 
for long listening sessions, we recommend an external 
amplifier as discussed below. 
 
If you use personal FM, cassette or CD players, you probably 
also know all about those compact amplified speakers 
designed specifically to plug into the stereo jack of compact 
personal stereos. These speaker setups have a built-in 
amplifier circuit and their own separate batteries. Any of 
these devices should work well with your receiver.  Radio 
Shack carries a variety of amplified speaker pairs as well as 
several monaural utility amplifiers.  Even though stereo 
jacks are used, remember that the receiver audio output is 
monaural.   
 
An external amplifier can also be a rewarding do-it-yourself 
construction project.  One-half to 2 watts will provide 
generous and ample speaker volume.  In fact, if building this 
receiver has kindled your interest in building something on 
your own, you could get started by duplicating the same LM386 
audio circuit used in this receiver.  Use the same parts 
values and physical positioning as we did.  The volume 
control may be omitted, since you already can control the 
receivers volume.  The amplifier will operate on 6 to 15 
volts DC.  All needed parts are available at Radio Shack 
stores.  Youll get plenty of volume for any size of utility 
or communications speaker.  (AUTHORS NOTE: I have fully 
tested this use of a second identical LM386 IC circuit with 
speaker and can recommend it highly to all who cant confine 
all this listening excitement to one or two headsets!) 
 
VERY IMPORTANT: 
A monaural 1/8 plug will fit the receivers stereo 
jacks.  HOWEVER, the plug must NOT be pushed all the way into 
the jack, because it will short out the audio output.  If you 
have reason to use a mono plug, insert it just far enough for 
the tip to make firm contact with the first section inside 
the jack. 
 
ABOUT THE 5 TUNING RANGES OF YOUR RECEIVER  
						

							MFJ-8100                                                                 
World Band Receiver 
 
16 
The purpose of the following information is to give newcomers 
a general idea of what to expect to hear in each of the 5 
frequency ranges tuned by your receiver. 
 
First, please understand that the frequency markings on the 
tuning dial can be only approximate.  They indicate the 
general neighborhood of major frequency bands and have an 
accuracy only within a few hundred KHz.  (If you are 
wondering what it would take to make the dial perfectly 
accurate, imagine an adjustable trimmer capacitor AND an 
adjustable coil for EACH band!  The process of making these 
many adjustments is called alignment and also requires the 
use of frequency measuring equipment far more costly than the 
receiver.) 
 
Whenever you hear a broadcast of special interest to you 
which you would like to be able to find again, make a note of 
the time, frequency band, and approximate dial position. In 
fact, such notes are called a Shortwave Listening Log. A 
sample log page is printed in this book which you may copy to 
make your own logbook.  Or, use your computer to design the 
style of logging pages best for you. 
Range A: 3.5 to 4.3 MHz. 
The primary purpose of this tuning range is to make it very 
easy for you to listen to ham radio stations at night on what 
is known as the 80/75 Meter band.  From 3.5 to 3.8 MHz, 
youll hear mostly Morse Code signals.  From 3.8 to 4.0 MHz, 
you will hear SSB voice conversations from all around the 
nation.  Youll hear both sides of most conversations. 
You may hear occasional shortwave broadcasts mixed in among 
the hams in the 3.9 to 4.0 MHz region and possibly in the 90 
Meter band, 3.2 to 3.4 MHz. 
Range B: 5.85 to 7.40 MHz.  
The main purpose of this tuning range is to give you lots of 
strong shortwave broadcasts in late afternoon and throughout 
the  
night on the 49 meter band, 5.95 to 6.2 MHz.   
The 40 meter ham radio band is 7.0 to 7.3 MHz, and you will 
also hear foreign broadcasts among the ham CW and SSB 
signals.  
Range C: 9.5 to 12.00 MHz. 
This band lets you tune all of the popular 31 meter broadcast 
band, 9.5 to 9.9 MHz.  You can also find the WWV time 
standard signal at 10.0 MHz (or on Band D at 15.0 MHz.)  The  
						

							MFJ-8100                                                                 
World Band Receiver 
 
17 
30 meter ham band (CW and RTTY only in the USA) is at 10.1 to 
10.15 MHz. This tuning range is generally busy 24 hours a 
day. 
Range D: 13.2 to 16.4 MHz. 
On the 20 Meter ham band (14.0 to 14.35 MHz), you can hear 
strong CW and SSB voice signals from around the world 
throughout the day and well into the evening.  This is the 
most active and crowded of the international ham radio bands.   
You also are able to tune the 21 Meter shortwave broadcast 
band (13.6 to 13.8 MHz), and all of the 19 Meter band (15.1 
to 15.6 MHz).  Station WWV at 15.0 MHz provides precision 
time and frequency information.   
The 19 Meter band is very good in the morning hours of winter 
and the late afternoon hours of summer. 
Range E: 17.5 to 22 MHz. 
This tuning range is provided to assure good listening 
variety during daylight hours.  It includes the 16 Meter 
broadcasting band (17.55 to 17.9 MHz), the 17 Meter ham band 
(18.068 to 18.168 MHz, and the 15 Meter ham band (21.0 to 
21.45 MHz).  Station WWV also broadcasts on 20 MHz. 
SHORTWAVE LISTENING IN GENERAL 
 
In addition to the specific bands highlighted above, 
youll hear thousands of OTHER shortwave signals.  Many will 
be military or government Morse code transmissions, plus very 
odd noises of weather FAX, wire service and other data 
transmissions.  You can also hear government or military SSB 
voice transmissions and even an occasional unlicensed 
pirate station. 
 
A rule of thumb is that the lower frequency ranges (A, B, C) 
are most active during the late afternoon, evening and 
through the night.  The higher frequencies (D and E) 
generally are most active during daylight hours. 
 
See the conclusion of this book for information on getting 
more information! 
 
IN CASE OF DIFFICULTY 
Following are minor problems which are easy to solve: 
 
Extremely weak volume on all bands.  
						

							MFJ-8100                                                                 
World Band Receiver 
 
18 
Test your headphones on a personal stereo and compare them to 
one or more other headphones.  It is very possible for 
inexpensive headphones to become defective.  Also, make sure 
that the battery is in good condition. 
 
Steady, high-pitched squeal or whistle. 
Regeneration control is turned too far clockwise. 
 
NOTE: We have designed this book and the receiver itself to 
assure that you can install it easily and enjoy.  If, after 
installing your receiver, double-checking  steps and going 
over the preceding trouble-shooting suggestions, you are 
still having a problem, please contact MFJs Technical Help 
Department at 1-800-647-TECH.  Before calling, please be 
prepared to explain your exact difficulty as exactly as 
possible. 
NOTES FOR HAM OPERATORS & EXPERIMENTERS 
 
This receiver has a single intended purpose: to help 
newcomers, young and old alike, to enjoy tuning the sheer 
magic of shortwave radio.  Youll quickly gain the skill of 
finessing the regeneration control to choose AM shortwave 
broadcasts, SSB or CW/RTTY.   The MFJ-8100 just might be the 
very best regenerative receiver ever designed, but it is not 
intended to be all things to all people. 
 
The MFJ-8100s PC-board is a very roomy platform which may 
SEEM to invite countless modifications.  However, please 
remember the original purpose of the receiver before 
hacking.  Its a beginners first shortwave receiver, 
designed for the most popular SWL broadcasts plus a SAMPLING 
of our ham bands.  If you expect to pass it on as a gift or 
resell it, it would be prudent to accomplish any desired 
modifications on the outside of the receiver itself.  For 
example, the function of the RF gain control can be 
duplicated with a pot at the antenna connector with no 
drilling required.  Similarly, alternative DC power, 
additional audio amplification or audio filtering can be 
provided externally.  If you change any values in the L-C 
tuning in order to try a band of special interest, be sure to 
note such changes in this manual.  Remember that changing C3 
or any inductance affects the tuning range of ALL the bands.   
  
						

							MFJ-8100                                                                 
World Band Receiver 
 
19 
[Authors Hint:  To save you time as well as wear and tear on 
the PC-board, heres what my own curiosity showed:  reducing 
C3 can easily bring in 12 and 10 Meters on Band E.  However, 
attempts to increase this capacitance beyond 220 pF without 
ALSO increasing total inductance are pointless if youre 
looking for good 160 Meter performance.] 
 
While its not intended as a communications receiver, the 
very fact that the MFJ-8100 covers all or part of so many 
different popular CW bands might intrigue some QRP 
enthusiasts interested in multi-band portable trans-
receiving.  The author conducted a few simple tests using an 
HW-9 for transmitting, side by side with the 8100 on 30, 20, 
17 and 15 meters.  You will want T-R switching to short the 
receiver antenna input to ground and also to mute the audio.  
Plan on a separate keying sidetone.  Frequency spotting must 
be done with a very low RF level.  Receiver stability when 
switching the antenna input is amazingly good even at 21 MHz.  
While the 8100 is not represented as a communications 
receiver, you indeed can have some multi-band QRP fun with 
it.  And FUN is exactly what this great new receiver is all 
about! 
 
Look at it this way.  If you take your multi-band QRP mini-
transmitter and MFJ-8100 on a trip and happen not to work DX 
or anybody else, you can still dial up BBC, VOA, Moscow, and 
many more places of our ever-shrinking global community! 
 
 
 
 
CONCLUSION 
 
If you really enjoy shortwave radio listening, youll 
probably yearn for and eventually get a more elaborate 
receiver.  You might even work on getting a ham radio license 
and setting up a station for transmitting and receiving.  As 
the years go by, we have a hunch that youll always remember 
the first thrills of listening to your MFJ-8100.  And, 
because its rugged, compact, and far more sophisticated than 
the first receivers of yesteryear, we suspect youll actually  
						

							MFJ-8100                                                                 
World Band Receiver 
 
20 
keep it and keep on listening to it when nobody else is 
looking! 
LEARNING MORE 
The purpose of your Receiver and the details provided in this 
instruction manual are to help you become better acquainted 
with radio communications and electronics: as a hobby, as a 
possible profession, or both. 
 
Among the hundreds of publications available, we are pleased 
to recommend the following as especially helpful for radio 
newcomers and people of any age who are young at heart! 
 
Getting Started in Electronics 
  by Forest Mims III (Radio Shack) 
Now Youre Talking: Discovering the World of Ham Radio  
  (ARRL, Newington, CT 06111, also sold by Radio Shack) 
 
Plus these MFJ publications: 
 
Shortwave Listeners Guide for Apartment/Condo Dwellers  
  by Ed Noll, W3FQJ  (1991, MFJ Edition No. 36) 
The Wonderful World of Ham Radio, 
  by Richard Skolnik, KB4LCS (1990, MFJ Edition No. 35) 
 
Or, if youd like just one copy of one magazine thats all 
about ALL the signals you may hear on your MFJ-8100, you can 
find the latest issue of POPULAR COMMUNICATIONS at any 
serious magazine stand.  Its a fascinating publication.  
Happy listening! 
 
 
 
 
 
 
 
 
 
 
 
 
SOME HELPFUL WORDS & ABBREVIATIONS