Four State QRP Group Cyclone 40 User manual
Instruction Manual
Cyclone 40
40 Meter Transceiver
Revision A.0
Copyright 2013
David Cripe NM0S
&
Four State QRP Group
Updated 2/11/14
Introduction
Thank you for purchasing a Cyclone 40 transceiver kit. We hope you will enjoy
building it and have many QSOs with it to the 40-Meter band. This kit is
comprised of high-quality components, a silkscreened, solder-masked, double-
sided PC board, and pre-drilled, silkscreened enclosure.
Theory of Operation
The Cyclone is 40M QRP CW transceiver, designed to maximize performance
with a minimum of components, cost and assembly effort. To achieve this, a
number of very unusual circuits have been employed.
The heart of the Cyclone is the 4 MHz variable-frequency oscillator, made up of
transistor Q6, inductor L5, capacitors C14 and C15, and resistor R5. This
frequency of the oscillator is tuned by changing the inductance of L5, which is
done by moving a brass screw inside the center of L5. The conductivity of this
screw essentially blocks the inductor's magnetic field, effectively changing the
area inside the inductor, reducing its inductance. Such a circuit is called a
Permittivity-Tuned-Oscillator, or PTO. The frequency range of this oscillator is
nominally 3.87 to 4.00 MHz.
A second oscillator operates at a fixed frequency of 11.001 MHz. This is the
Local Oscillator, comprised of crystal X5, resistors R4, R13, capacitors C16 and
C17, and transistor Q11. The output of this oscillator is mixed against the IF
signal to demodulate the received audio, and also mixed with the PTO
frequency to generate the transmit frequency of the radio.
The IC U1, a 74HC240 performs many functions within the transceiver. This
device contains eight inverting logic gates, in two banks of four. These gates
are controllable into a 'Tri-State' output, where the output voltage is neither high
nor low, but instead a high impedance. One bank of four gates is used for
transmit functions (U2, pins 2, 4, 6, 8, 12, 14, 16, and 18), while the second
bank of four gates is used for receive functions (U2, pins 3, 5, 7, 11, 13, 15, and
17). These two banks are enabled by a logic-low input at pins 1 and 19,
respectively.
When in the transmit mode, the 4 MHz PTO and 11 MHz LO signals are mixed
in Q8 to create the 7 MHz transmit frequency. This is filtered by T3 and T4, and
amplified by U2-2 and -4. The output of U2-16 is fed to U2-6 there it is inverted.
The outputs at U2-18 and -14, respectively, comprise a complimentary, push-
pull signal at the transmit frequency, driving the gates of PA transistors Q3 and
Q4.
The transmit power amplifier utilizes power amplifier transistors Q3 and Q4 in
push-pull Class-E mode to generate 4W nominally from 12v, at 85% efficiency.
When the transmitter is keyed, transistor Q7 is driven on, applying DC power to
the PA drain choke L4, allowing Q3 and Q4 to make power.
When in the receive mode, the PTO output is fed to U2, pins 15 and 17,
buffering and amplifying the sine-wave oscillator signal to create a logic-level
square wave signal. The output of U2-5 is fed to U2-13 to create a logically-
inverted signal at U2-7. The signals at U2-3 and -7, respectively, comprise a
complimentary, push-pull signal at the PTO frequency, driving the gates of PA
transistors Q3 and Q4. The received signal is switched by these transistors,
converting the 7 MHz received signals to 11 MHz for the IF filter.
The IF filter, comprised of X1-X4, is a four-pole, 11 MHz crystal filter with a
Gaussian shape, filtering the CW signal with minimal ringing. The filter is fed
directly from the center tap of the PA output transformer, consequently, no
transmit/receive switching of the antenna is required.
The output of the IF filter is amplified by Q5, and fed to the active mixer circuit of
Q1 and Q2. The 11 MHz LO signal is fed into the emitters of Q1 and Q2, mixing
against the IF signal, producing demodulated audio at the primary of transformer
T2.
The secondary of transformer T2 feeds the audio signal into the emitter of Q10,
the first audio amplifier. This feeds the first stage of U3, a TL072 op amp. This
is configured as a high-gain bandpass filter, adding further selectivity to the
audio signal.
Audio peaks cause current conduction by Q9, the AGC detector. This charges
C33, and provides current to base of Q12, the AGC attenuator. Transistor Q12
is operated as a variable attenuator, controlled by its base current. This audio-
derived AGC loop is effective at attenuating and limiting large audio signals.
The audio signal is then fed through the volume control potentiometer R6, to the
second stage of U3, a unity-gain amplifier with an output buffered by
complimentary audio amplifier transistors Q13 and Q14. These transistors feed
the headphone though J2. The amplifier feeds the tip and ring connections of
the headphone jack, placing both headphone elements of a stereo headset in
series, reducing the current consumption of the amplifier.
When the transmitter is keyed, the mute switch transistor Q15 is closed, and
limits the passage of audio transients through the audio amplifier.
A PIC microcontroller U4 serves both as a frequency counter, as well as the
sidetone oscillator. Pressing the FREQ counter at the side of the enclosure
activates the counter, which counts the VFO frequency, and sends four digits of
the count (excluding the megahertz digit) as CW characters to the headphone
jack. The counter works both on transmit and receive. Coding for the counter
was provided by Adrian Hill, KC0YOI.
First Steps
Before getting started with building the receiver, take some time to organize and
familiarize yourself with the parts provided and check them against the Bill of
Material. Building over a cookie sheet is recommended to minimize parts being
lost. If parts are missing in your kit, send an email to Terry Fletcher, WA0ITP at
Schematic files are provided as part of documentation package. It is highly
recommended to print a couple of copies at 11 X 17 inch format at your local
UPS Store, Staples, etc. As you build, use a highlighter to mark off parts that
have been soldered onto the PCB on one copy. When you think you are done,
you can check that copy to verify that all of the parts have been installed. Build
section schematics are also provided for convenience that match up with the
build steps with their parts call-outs.
It is helpful to acquire the necessary tools and supplies before beginning. These
include:
*Soldering iron – Preferably thermostatically controlled.
*Fine 60/40 rosin core solder
*Wire strippers
*X-Acto knife
*Diagonal cutters
*Needle-nose pliers
*Phillips screwdriver
*Non-metallic alignment tool
*Electrical tape
*Clear fingernail polish
*Magnifier
*Rubber Bands
*Digital volt-ohm-meter
Soldering is not hard if the proper procedure is followed. The soldering iron is to
be used to heat up the PC pad and component lead, and the solder applied to
the pad, where it melts and flows into the hole. Do not melt the solder onto the
tip of the iron and then attempt to dab it onto the joint – a defective connection
will result! After soldering, check the top (component side) of the board, to be
sure the solder has filed the hole completely, and wicked up around the
component lead. Re-heat and apply more solder if necessary.
The PC boards used for the circuit and for enclosure are contained in two
panels, with the individual boards separated by V-groves. To begin assembling
the kit, the boards must be separated. Placing a panel on a table or workbench
so that the v-groove rests over the edge, the boards may be cleanly separated
by pressing down firmly on each section.
CAPACITORS
The ceramic monolythic capacitors used throughout the kit are small and their
markings not always easy to read. Use a magnifier to verify their values before
installing. Electrolytic capacitors must be installed in the correct polarity. The
cases are marked to indicate the negative terminal, which goes into the round
pad on the board.
Install the capacitors, solder and trim the leads. Check off each part as you
install it.
After C15, the dipped silver mica capacitor is installed, save the leads you
trim off of it. Set them aside – you'll need them later!
√
Ref Value Marking Type
C14 0.0047 472 or 4N7 Plastic
C19 0.01 103 Ceramic Monolythic
C25 0.01 103 Ceramic Monolythic
C30 0.01 103 Ceramic Monolythic
C32 0.01 103 Ceramic Monolythic
C1 0.1 104 Ceramic Monolythic
C2 0.1 104 Ceramic Monolythic
C21 0.1 104 Ceramic Monolythic
C22 0.1 104 Ceramic Monolythic
C23 0.1 104 Ceramic Monolythic
C29 0.1 104 Ceramic Monolythic
C31 0.1 104 Ceramic Monolythic
C26 10 10u or 106 Aluminum Electrolytic
C33 10 10u or 106 Aluminum Electrolytic
C37 10 10u or 106 Aluminum Electrolytic
C28 100 100u or 107 Aluminum Electrolytic
C34 100 100u or 107 Aluminum Electrolytic
C35 100 100u or 107 Aluminum Electrolytic
C24 470 470u or 477 Aluminum Electrolytic
C6 1000p 102 or 1N0 Ceramic monolythic
C7 1000p 102 or 1N0 Ceramic monolythic
C8 120p 121 Ceramic monolythic
C11 120p 121 Ceramic monolythic
C39 120p 121 Ceramic monolythic
C10 180p 181 Ceramic monolythic
C5 220p 221 Ceramic monolythic
C13 270p 271 Ceramic monolythic
C12 300p 301 Ceramic monolythic
C15 330p 331 Dipped Silver Mica SAVE THE LEADS!
C9 470p 471 Ceramic monolythic
C36 470p 471 Ceramic monolythic
C38 470p 471 Ceramic monolythic
C18 56p 560 or 56j Ceramic monolythic
C27 1500p 152 or 1N5 Ceramic monolythic
C20 68p 680 or 68j Ceramic monolythic
C3 82p 820 or 82j Ceramic monolythic
C4 82p 820 or 82j Ceramic monolythic
C16 82p 820 or 82j Ceramic monolythic
C17 82p 820 or 82j Ceramic monolythic
RESISTORS
Next, install the resistors.
√
Ref Value Marking Description
R24 330 Orange-Orange-Brown 1/4W
R9 470 Yellow-Red-Brown 1/4W
R3 680 Blue-Grey-Brown 1/4W
R4 1.0k Brown-Black-Red 1/4W
R7 1.0k Brown-Black-Red 1/4W
R10 1.0k Brown-Black-Red 1/4W
R8 1.0M Brown-Black-Green 1/4W
R13 1.0M Brown-Black-Green 1/4W
R20 1.0M Brown-Black-Green 1/4W
R21 1.0M Brown-Black-Green 1/4W
R23 1.0M Brown-Black-Green 1/4W
R26 1.0M Brown-Black-Green 1/4W
R27 1.0M Brown-Black-Green 1/4W
R28 1.0M Brown-Black-Green 1/4W
R2 1.5k Brown-Green-Red 1/4W
R1 100k Brown-Black-Yellow 1/4W
R11 100k, 10t
104 Blue Pot
R5 10k Brown-Black-Orange 1/4W
R15 10k Brown-Black-Orange 1/4W
R22 10k Brown-Black-Orange 1/4W
R6 10k - Volume Control
R16 10k, 10t 103 Blue pot
R12 18k Brown-Grey-Orange 1/4W
R17 3.3k Orange-Orange-Red 1/4W
R19 3.3k Orange-Orange-Red 1/4W
R25 3.3k Orange-Orange-Red 1/4W
R14 330k Orange-Orange-Yellow 1/4W
R18 470k Yellow-Violet-Yellow 1/4W
TRANSFORMERS AND INDUCTORS
Next, wind the toroids, beginning with L1.
Locate the three toroids, and the 22AWG magnet wire – the heavier gauge of
the pieces supplied. Cut a 20” piece from it. Take one of the toroids, and wind
21 turns around it with the wire. Remember that turns are counted as the
number of times the wire passes through the center of the toroid. Space the
turns evenly around the core. It is essential that the turns are pulled snugly
around the toroid, so that there is no slack between the wire and core. When
complete, strip and tin the wire ends prior to inserting on the PC board. Cut the
wire ends to about 1/2”.
There are a number of methods for stripping the insulation from magnet wire.
The wire provided in the kit is thermally strippable. If you have a higher wattage
or thermostatically controlled soldering iron, the heat from this (at least 750
degrees F) will be sufficient to strip the insulation from the wire. Alternately,
insulation may be removed using sandpaper of a a sharp hobby knife, prior to
tinning.
With the leads of the leads stripped, mount the toroid to the board, making sure
the leads are pulled snug from the back of the board. After soldering, inspect the
joints closely to be certain of a good joint. Resolder the joints if necessary.
[ ] L1 – 21 turns on T50-2
Inductor L2 is constructed in the same way using the remaining 22AWG wire,
but with 12 turns. Strip the leads, and mount to the board.
[ ] L2 - 12 turns on T50-2
Transformer T1 is constructed next. It is wound with three windings, two
primaries and one secondary, of 12 turns each. There are three pieces of
26AWG magnet wire provided, each a different color to help keep windings
straight. Two will be 10” long, and the other much longer. Cut a 10” piece from
the longer piece.
Wind each of the three wires twelve turns on the core, one at a time. When
finished it should look like the picture below. Double check that each wire has
the 12 turns, and that the order of the colors is the same at start and finish. Strip
the insulation from the windings, and install on the board. Pull the leads firm
from the rear of the board to assure the winds are snug on the toroid.
[ ] T1 Toroidal Transformer
Figure 1: Winding of T1
Install the remaining transformers at this time. Transformer T2 is a blue audio
transformer. Notice there is a letter 'P' printed on one side of T2, designating the
primary terminals. Be certain that that this transformer is installed with the
primary corresponding to the pads marked 'P' on the board. Bend the mounting
tabs over to provide mechanical strength, and solder them too.
[ ] T2 Audio Transformer
Transformers T3 and T4 are shielded IF transformers. Locate and install these
also.
[ ] T3 - IF Transformer
[ ] T4 - IF Transformer
Locate and install L3, the 100uH molded choke. It will be marked '100uH'.
[ ] L3 100uH
Do not install L4 or L5 at this time.
CRYSTALS
Install all five 11.000 MHz crystals, X1 through X5
[ ] X1
[ } X2
[ ] X3
[ ] X4
[ ] X5
SEMICONDUCTORS
Locate the 8-pin DIP IC socket. Install it in the U4 position, making certain to
align the polarity notch of the socket with the mark on the PC board, facing the
left side of the board.
[ ] 8-pin DIP socket U4
Identify and install the following components. Be certain that their polarity is
correct, and that they match the board silkscreen symbols.
Transistor Q8 requires a heat sink, included in the kit. Install the heat sink prior
to installing Q8 on the board.
√
Ref Value Description
D1 1N914 Glass diode
D2 SA15 Surge suppressor
U2 78M05 5v regulator, TO-220
U1 74HC240 Octal Inverter, DIP-
20
U3 TL072 Dual OpAmp, DIP-8
U4 PIC12F609
Counter IC
Q1 2N3904 TO-92
Q2 2N3904 “
Q5 2N3904 “
Q10
2N3904 “
Q12
2N3904 “
Q13
2N3904 “
Q9 2N3906 “
Q14
2N3906 “
Q6 2N7000 “
Q15
2N7000 “
Q8 MPF102 w/ Heat Sink
Q11
MPF102 “
Q7 ZTX749 “
Q3 ZVN4206A “
Q4 ZVN4206A “
HARDWARE, SWITCHES AND CONNECTORS
Take the T-nut and the front panel. The T-nut inserts through the front of the
front panel. The front panel location for the T-nut has mounting holes for either
the three-prong or four-prong versions of the T-nut. The mounting prongs of the
T-nut may not exactly align with the holes in the board, so you may need to re-
align them with your needle-nose pliers.
Locate the brass screw provided in the kit. Notice one end has been cut, and
one end is finished. Screw the finished end into the T-nut to verify that its
threading is clean and smooth, then remove.
Place the T-nut flat on your workbench, placing the enclosure front panel front-
side down over it, so the mounting prongs pass through the appropriate holes in
the board. It may be a snug fit. Press the board down over the prongs until the
board bottoms out on the T-nut.
The prongs should be soldered at the back side of the board. You may need a
higher wattage iron to heat the T-nut sufficiently to melt the solder. Do not
attempt to solder the center pedestal of the T-nut.
[ ] T-nut
Solder SW2, the 'FREQ' pushbutton switch, to the board. Be certain it is flush to
the board before soldering.
[ ] SW2 FREQ pushbutton
Solder J1 and J2, the Key and Headphone jacks to the board. These are 1/8”
stereo connectors. Be certain that they are pressed flush to the board before
soldering, and re-solder while pressing down if necessary to assure they are as
close as possible too the board.
[ ] J1 – 1/8” Stereo Jack – Key
[ ] J2 – 1/8” Stereo Jack – Headphones
Adjacent to the KEY jack are three pads connecting to the jack tip and ring, and
to the transmitter keying line. This is to facilitate addition of an optional keyer
circuit. If one is not to be used, jumper the TIP pad to the adjacent key pad at
JP1 using a snipped-off component lead.
Install the J3, the BNC antenna jack. It will require some time to heat the
ground pins in order to solder them.
[ ] J3 – BNC
Cut two, three-inch lengths of 22 gauge insulated, stranded wire. Strip 1/4” of
insulation from both ends of each piece. Solder them on to the terminals of the
coaxial power connector. The shell of the connector is the negative terminal,
and the center pin is positive. Solder the other ends of the wires to the
corresponding '+' and '-' pads at the left edge of the board. Verify that the shell
of the connector is connected to the '-' pad, the ground plane of the board.
The mating connector for this is a standard 2.5mm/5.5mm coaxial power
connector, wired so that the center conductor is positive.
ENCLOSURE
Take the finished circuit board, and, using the 3/8” screws inserted through the
bottom of the board, install the 1.5" aluminum spacers on the top side. Invert
the board, so that it rests on the spacers. Rest the front panel against the front
edge of the circuit board. Be sure that the key and headphone jacks fit through
the holes on the front panel, and the edge of the front panel rests evenly against
the workbench surface. Assemble the four side panel pieces around the main
board, and use rubber bands to temporarily hold them in place, making sure that
the edges are perfectly flush. Be sure that the horizontal silver stripes on the
side panels rest against the edge of the circuit board, and that the vertical slots
are toward the rear of the unit. Using a soldering iron (30W to 40W may be
required to supply sufficient heat) place a small, pea-sized, solder fillet at the
upper corner of the juncture of each of the four side panels. Flip the assembly
over so that it is right-side-up, and remove the aluminum spacers. Add small
solder fillets on the upper corners of the four side panel junctures. Inspect to
assure that each joint is flush and square, and re-adjust the solder joints if
necessary. Re-invert the assembly, and attach the circuit board to the side
panels using solder fillets about 1/2" inside from each corner.
It is NOT recommended to solder the entire length of the joints. If it would be
necessary to disassemble the enclosure at a future it would be nearly
impossible to do so.
PTO
Locate the threaded nylon PTO coil form, the remaining 26 AWG magnet wire,
the brass screw, and the two leads from C15. Using an indelible marker or
hobby knife, mark the nylon coil form 1/8” (3.5 mm) from each end. Screw the
brass screw entirely into the nylon spacer, finished end first. Fix the nylon
spacer horizontally into a bench vise, clamp, or 'third hand', so that the marks
are at the top.
Take the leads saved from C15. Straighten them as much as possible. Take
one lead, and hold it vertically, near the top with your needle nose pliers.
Position the bottom of the lead on one of the marks on the nylon spacer. Touch
your soldering iron to the lead about 1/4” from the bottom of the lead to heat it.
As the plastic of the spacer melts from the heat of the lead, firmly and quickly
force the hot lead straight down into the plastic until you feel a slight resistance
before it bottoms out on the screw inside. Immediately remove the iron, while
holding the lead in position until the plastic cools and sets. Check with your ohm
meter that there is NO continuity between the lead and the brass screw, while
rotating the screw through a complete turn. Reheat the lead and pull it out
slightly of continuity is present. Repeat with the second lead. Leave the
assembly in the clamp for the time being.
Take the 26 AWG magnet wire. Strip and tin 1/4” of one end. Bend the end in
the middle of the tinned section into a sharp 'v'. Place this over one of the newly
inserted leads, so that the end of the 'v' points away from the center of the coil
form. Hold the wire about 1/16” (1.5 mm) from the surface of the plastic, and
crimp in place with the needle nose pliers. Solder into place quickly, and
promptly remove the iron before the lead loosens from the plastic spacer.
Remove the spacer from the vise or clamp, and remove the screw from the
center. Wrap the 26AWG magnet wire 22 turns around the spacer. Strip a ¼”
section of the wire where it touches the second PTO lead. Pulling the wire snug
around the spacer, bend the magnet wire where it touches the PTO lead, and
solder it into place. Trim off the excess wire.
Trim the length of the PTO leads extending from the spacer to 1” (25mm). Using
needle nose pliers to support the lead at the body of the spacer, bend it into a
‘knee’ shape as per the illustration below. Insert the leads into the PTO position
on the board (labeled L6), and solder into place. The PTO coil should be
directly above its mounting pads.
Figure 2: Wound PTO Coil
Figure 3: PTO Coil with ‘knees’
Insert the screw through the front panel T-nut until it touches the end of the PTO
coil form. Gently bend the PTO leads until the end of the screw lines up with the
threaded hole in the PTO coil form. Continue screwing the brass screw into the
PTO coil form until the end of the screw is approximately 1/8” from the end of
coil form, directly even with the end of the coil winding.
Next, we shim the screw so that it fits the tuning knob. Take a 4” strip of black
electrical tape and wrap it around the exposed end of the PTO screw, flush with
the T-nut. Cut off any tape that extends past the end of the screw. Test fit with
the large knob to insure a reasonably close fit. Remove or add tape as
necessary. Install the knob flush with the front panel.
Install the small knob over the volume control shaft. With the switch in the OFF
position, make sure the marker on the knob is aligned with the line on the front
panel.
Take time now to give the board a close visual inspection. Hold the board up to
light to make certain that all holes have been soldered. Using a magnifier,
inspect all solder joints for quality, and touch-up any needing it. Inspect for
solder blobs or other possible shorts. Double check that all polarized
components have been installed properly.
Install the bottom cover to the enclosure, using the 1/2” screws and 1/4” spacers
at the bottom of the board, and the 1.5” threaded spacers at the top of the
board.
Locate a regulated 12v supply. Assemble a power cable using a 2.5x5.5mm
coaxial power plug, center positive. Fuse the line with a 1A fast-blow fuse.
Make up a cable for the key. Obtain an 1/8” audio plug, and wire your key to the
tip and shell. The shell is grounded, and the connector tip is the keying line.
ALIGNMENT
With the Cyclone power switch OFF, plug a pair of headphones or ear buds into
the headphone connector. Turn on the 12v supply, and the power switch of the
Cyclone. Advance the volume control fully. You should hear a slight hiss of the
audio amplifier circuitry.
If you hear hiss in the headphones, and the power supply fuse has not blown,
we may proceed with alignment.
The first task is alignment of the PTO coil. It is necessary to set the PTO
frequency at 4.000 MHz when the PTO screw is fully inserted. Press the FREQ
button at the side of the enclosure. You should hear a sequence of four CW
numerals played in the headphones. These four digits represent the count in
hundreds of kilohertz, tens of kilohertz, kilohertz, and hundred hertz. This
represents the transmit frequency, which is calculated in the counter IC by
subtracting the PTO frequency from the 11 MHz LO frequency.
If the PTO is aligned, the count should be 0 – 0 – 0 – 0. If the number begins
with a 9, then the PTO frequency is too high, and the PTO turns should be
spread. If the number is greater than zero, than the PTO frequency is too low,
and the coil turns should be pinched together toward the center of the coil form.
You will also notice a birdie in the headphones around a PTO frequency of 4.000
MHz. This serves as an audible band edge marker, and is a helpful tool to
assist in alignment of the PTO coil.
Once the PTO is within a kilohertz or two of 4.000 MHz, coat the PTO coil
winding with a thin coat of clear fingernail polish to fix the turns in place.
Next, the transmit-mixer filter transformers must be peaked. Unscrew the PTO
screw until a second birdie is heard in the headphones. This occurs at
approximately 3.930 MHz PTO frequency, and serves as a mid-band indicator.
Key the rig. With L4 not installed, the rig may be keyed continuously with no risk
of damage to any component. With your digital voltmeter, observe the voltage
on TP1 and TP2, which are the final amp drive signals. They should both be in
the 2 to 3 volt range. If the reading is erratic, it may be due to RF from the drive
signal entering the meter. You may add a 10k resistor between the test probe of
the meter and the test points to reduce the effects of RF.
While monitoring TP1, adjust the R11 BALANCE pot until the TP1 reading is 2.0
volts. Then, using your non-metallic alignment tool, alternately adjust T3 and T4
several times until the DC voltage at TP1 is maximized. The peak is fairly sharp,
and may require patience to find.
When the voltage at TP1 is maximized, re-adjust the BALANCE pot until the
voltage at TP1 matches that at TP2. Unkey the transmitter.
Press the FREQ button, and note the four digit count. Key the transmitter, and
while it is keyed, press the FREQ button. Note the four digit count. The two
numbers should differ by 20 to 40. If it is much larger than this, it is an indication
that T3 and T4 are tuned to a spur frequency. Repeat the T3-T4 alignment step,
and re-BALANCE.
Next, the transmit/receive frequency offset is adjusted. This is done in two
processes. Press the FREQ button, and record the four digit count output.
Then, when keying the transmitter, press the FREQ button, and record the
count. The TX count should be higher than the RX count by 20 to 40. One at a
time, solder-bridge in a section of the offset capacitor, which is set of copper
pads on the bottom of the board next to the PTO inductor. Start from the one
closest to the center of the board, and add the next one out. Measure the
difference in FREQ count between RX and TX, and if the TX count is higher
than the RX count by more than 5, add another section of the offset cap.
Finally, fine-tune the offset by adjusting the OFFSET pot R16 until the four digit
frequency count matches on transmit and receive.
If you prefer to only hear a three-digit frequency count, it is possible to disable
the final, hundred-Hz-count digit by installing a wire jumper at JP2
With this complete, remove the bottom cover, install L4, and then install top and
bottom covers. You are done and ready to put your Cyclone on the air!
TROUBLESHOOTING
If your Cyclone does not operate after assembly, repeat the visual inspection of
solder joints. Compare the component placement diagram with the instructions
to be certain that all components were installed in their correct locations.
A check of voltages at strategic locations on the board while under power can
serve to isolate problems to a particular circuit. The following table lists nominal
voltages on the unit on transmit and receive. If an entry is marked 'xxx' do not
attempt to measure it during transmission.
Component
Pin
Rx Voltage
Tx Voltage
Q1 E 4.3 4.3
Q1 B 5 5
Q1 C 12 12
Q2 E 4.3 4.3
Q2 B 5 5
Q2 C 12 12
Q3 S 0 XXX
Q3 G 2.5 XXX
Q3 D 0 XXX
Q4 S 0 XXX
Q4 G 2.5 XXX
Q4 D 0 XXX
Q5 E 4.3 4.3
Q5 B 5 5
Q5 C 5 5
Q6 S 0 XXX
Q6 G 2.5 XXX
Q6 D 2.5 XXX
Q7 E 12 12
Q7 B 12 11.3
Q7 C 0 11.5
Q8 D 12 XXX
Q8 S 6 XXX
Q8 G 5 XXX
Q9 E 5 5
Q9 B 5 5
Q9 C 0 0
Q10 E 0 0
Q10 B 0.6 0.6
Q10 C 2 - 3 2 - 3
Q11 S 2.5 XXX
Q11 D 4.3 XXX
Q11 G 0 XXX
Q12 E 0 0
Q12 B 0 0
Q12 C 0 0
Q13 E 5 5
Q13 B 5 5
Q13 C 12 12
Q14 E 5 5
Q14 B 5 5
Q14 C 0 0
Q15 S 0 0
Q15 G 0 12
Q15 D 0 0
U1 1 5.0 0
U1 19 0 5.3
U1 20 5.0 5.0
U3 1 5.0 5.0
U3 7 5.0 5.0
Figure 4: Component Placement
Table of contents
