-- o ICOM

onfinuedjromp.25
W inding a transformer ca n be tricky
when you' re try ing to get the right wire
sold e re d to the correct cir c u it boa rd
pad . Refer 10 T4 o n Figure 6. NOIe the dots.
These are "phasing "
dots. They indicate
which wires are on which end of the winding .
Numbers I and 2 are the ends of one wire,
3 and 4 are the ends of another, and 5 and
6 are the ends of another . Numbers 1,3, and
5 begin the coil and 2, 4 , and 6 are ar the
other end .
Notice, however that 2, 3, and 6 are co n­
nected together and go in one hol e in the
board. They are all at ground . Thus, there are
only 4 connectio ns 10 the circuit board.
You will probably need to use an ohmmeter
10 chec k which wires are co ntinuous after
winding the to ro id . A simpler way, however
is to use different colors of wi re . You can use
26 or 30 gauge wire inplace of No . 28 wire.
You may mix sizes if you have diffe rent colo
red wire ofdifferent sizes. This saves a great
deal of lime. The wire sizes should not be too
d issimilar , though .
Whe n you are working with th e wire
wound on a toroid , you will notice that it is
enameled for insulation. You will have to
either scrape the enamel off o f the wi re tips
wh ile you' re soldering il to the board, or mel!
it off with the soldering iron. Melting it o ff
works, but creates a mess. It helps to burn the
enamel with a match before scraping .
When winding toroids, space the turns
evenly . Do not bunch them.
- A shield a round th e VFO box c an be
tack-soldered to the board easily. Just a few
tacks to each side will do nicely . You
may have 10 remove it a time or two , so do
nOI
solder il down pennane ntly until the
very end.
e'This board is intended to fit nicely into a
project box that is available at Radio Shack. It
is approximately 6" x 5Jh" . You can mounl a
speaker against the side wall of the cabinet
top, where the vents are located, and is glue it
in place . First. glue a small rectangle ofcloth
to the box, and then glue the speaker to the
box. M ake sure the material covers only the
vents . The speaker must overla p the material
10 adhere to the box.
«Some components may have to be fonned,
trimmed, or clipped to properly fit the board.
This is especially true of trimmer capacitors
whi ch come in many , ma ny different sizes
and shapes. Do not be afraid to do some
"engineering" in thi s regard. A ham' s ability
to do thi s is what makes thi s hobby what it is.
- With a direct conve rsion receiver, il is extremely
important to make all connections
very solid , especially ground connections . I
recommend a double-sided PC board . Ifyou
keep grounding fore most in your mind, you
will do fine . If a part is to be grounded, you
may solder it nOI only to the pad on the underside
of the board but also to the upper side of
the board . This is why the copper is nOI
drilled out around the upper part of the board
for grounded pans . Use plenty o f solder
when you attach these parts to each side ofthe
board .
- Make coax and power ground connections
to the upper pan of the board. Simply solder
the shield to the board ground plane on the
upper pan of the board . The same holds true
fo r the power co nnection. Insert the positive
lead into the proper hole and and solder it to
the correct pad o n the underside o f the board.
Then, j ust solder the negative lead to the
ground plane .
- As with any DC receiver, you will hear
the signal you are tu ned to on both sidebands.
The superheterodyne rece iver by its very
nature o nly " hears " one sideband . Conseque
ntly , you will need to lune to the proper
sideband when you want to QSO a station
so th at you are nOI
way o ff frequency.
Tune on the " lowe r side" of the zero
beat. This will insure that you are in correct
position.
«Note the coax jumper from the VFO to the
mixer transformer T5. RG- 174 is handy for
this purpose.
T u ne up, Ope-ration, a nd Troub leshooting
If you have followed the steps above, you
have already gotten this rig in an opera ble
state. Simply align the VFO, tweak the driver
trimmer CI8, tweak the RF amp trimmer,
C23, set the RIT control R9 at hal f scale, and
hang on to your hal!
I have made every mistake possible in
building thi s rig . I wi ll gladly respond 10
written requests fo r help . I have tried to guide
you around some of them so that if you have
hesitated to stan a proj ect before, you will
give it a try thi s time .
Finding Parts
The pans list , Table
I, g ives a Rad io
Shack pan number for most pans needed for
this project. The more exotic ones, such as
variable capacitors , trimmer C4, toro ids ,
semicond ucto rs, dials, and printed circuit
board materials can be found in a number of
ma il order catalogs. One supplier in particular
is dedicated to carry ing parts for hornebrewers
.
Do nOl be afraid to scrounge around flea
markets , surp lus electronics pans houses, o r
your own j unk box for pans. My mono is:
" When in doubt , try it! " Most metropolitan
cities have surpl us houses that sell new (or at
least unused) pans at din cheap prices. You
just have 10 root around for a whi le 10 find
your treasures . I once found a whole box full
of vernier dials that I bought for two dollars
apiece. New, they are len dol lars. Persevere ,
and save on pans!
Good luck and happy home·brewing!1IJ
BIBLIOGRAPHY
Cornelio Nouel, " 40 Meters in a Nuts
he ll, " 73 Amateur Radio, March
1987.
DeMaw, QRP Notebook , ARRL, 1986.
Hayward and De Maw, Solid State oesign
for the Radio Amateur, ARRL,
1977.
Carr, " Ferreti ng out the Problem," Ham
Radio , J une 1988. An excellent instructional
on understanding toroids
and how to wind them.
10 METER
DX IS HOT!
AND YOU CAN WORK IT WITH
THE NEW RANGER AR 3500
• Compact Mobile Transceiver
• Microprocessor Controlled Design
• All Mooe SSB/CW/AM/FM
• Effective Noise Blanker
• Five Selectable Memory Channels
• Programmable Band Scan
• Large Six Digit Frequency Readout
• Split Frequency Repeater
Operation
• Dynamic Mic & Power Cable
• Mic with Frequency Scanning
Buttons (optional)
• Limited 1 Year FactOfY Warranty by
Clear Channel Inc. lssaquah, WA
SPECIFICATIONS
F~ Range: 28.0CX)l).29.9999 MHz in
100 Hz steps
Sena.: SSB/CW .15 IlV. FM/AM.3 "'v
Pour. sse 25W PEP, »N. CW, 8W FMIAM
Input: 12.5 V, 6A DC
Dlmeo.lona: 2.4"X7.7"XW Wt 3 Lb$.
We made a special purchase of
mese 'ine transceivers ancllhus
able to offer them at a very attractive
coce
Special!
X'~":,, $299 .95
AVAILABLE OPTIONS
100 Watt model Ieal lor detailsl
MI(: wi Freq. scan. Buttons·•.• .• ••• ••••S30oo
SP.1 Speech Processor" 30.00
CW Auto break-in & pwr contror 30.00
Service Manual AR3300IAR3500 20.00
3 Elemeol Beam. 26-30 MHz 89.95
Penetrator Mobile Anl 4195
Anlron A-99 vertical Base AnI. 49.95
RS7A Pwr Supply lor JaW Ranger 52.95
RS35A Pwr Supply lor 100WRanger 142.95
"sale price with radio purchase only
Oller ~mrted 10available stock
Seod a SASE lor cleIailed brochure
FOi ..~ 0rdIrI Ac:oIpIid
0rdIrIi.'ltd by 1 PM PST INppid UPS _ lily.
CuMtIly Prtclng A. I I.
COO IVISA /Me HutlilyUPSdII\., ... I ,.
No atrI ctIqIlDrc.o.D.Of VISA lIIIItftInt0r'dIrI
ORDER DESK ONLY - NO TECHN1CAL
800 854-1927
ORDER LINE .ndlor TECH HELP
619 44·
FAx (818) 744·1943
73 Amateur Radio - June, 1989 49