4SQRP Bayou Jumper 40 Meter CW Transceiver Installation guide

Assembly & Instruction Manual
Bayou Jumper
40 Meter CW Transceiver
For revB (Blue Panel) kits shipped after 1 Jan 2021
Copyright 2017, 2020
David Cripe NM0S
Jim Giammanco N5IB
&
Four State QRP Group
ACØBQ photo

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 1 of 46
PLEASE READ THIS ENTIRE MANUAL
BEFORE BEGINNING ASSEMBLY
Introduction
Thank you for purchasing a Bayou Jumper transceiver kit. We hope you will
enjoy building it and have many QSOs with it. This kit is comprised of high-
quality components, a silkscreened, solder-masked, double-sided PC board and
front panel, and hardware for mounting in a wooden enclosure.
This kit owes its genesis to the imagination of Jim Giammanco, N5IB, who
envisioned this project in homage to the classic ‘Paraset’ transceiver,
http://www.paraset.nl/ the legendary spy radio from World War II. Using the
same circuit architecture as the original, Jim brought it up to date with solid-
state circuitry, giving the user an authentic feel of the original radio without the
high voltages and scarce components of a tube circuit.
Jim named his creation the ‘Bayou Jumper’ after the popular KnightKit ‘Ocean
Hopper’ regenerative receiver that so many novice hams built a half-century
ago, and with a salute to his Louisiana heritage. His presentation on the project
was one of the most popular presentations at OzarkCon 2016. The Four-State
QRP Group is proud to be able to present the Bayou Jumper to the QRP
community.
The transceiver is comprised of two separate circuits, a crystal-controlled
transmitter and a regenerative receiver. The transmitter uses 4SQRP’s super
simple, super robust NS-40 transmitter circuit, with trademark on-board spiral
PCB trace inductors, and between 4 and 5 watts output power.
The Bayou Jumper utilizes a regenerative receiver, the same as the original
Paraset. No other receiver circuit provides the combination of sensitivity and
selectivity with low parts count. Regenerative receivers were popular among
hams for this reason. The receiver in the Bayou Jumper has been measured to
have a Minimum Discernible Signal (MDS) of better than -120 dBm, which is as
good as many commercial receivers. In the Bayou Jumper, the receiver tunes
independently from the transmitter frequency, so there is a ‘Spotting’ function to
allow the user to tune the receiver to the transmitter frequency.
Switching between transmit and receive is performed with a rotary switch, just
as was done with the original Paraset. You cannot get more simple and reliable
than that!

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 2 of 46
The entire transceiver was designed to fit inside a standard wooden box,
available from Hobby Lobby. It can be ordered here:
http://www.hobbylobby.com/Crafts-Hobbies/Wood-Crafting/Unfinished-Wood/Wood-
Rectangle-Box-Set-with-Silver-Handle/p/25426-GA0369
The on-line sale is for a set of three boxes, of which the smallest is used. The
boxes can be purchased individually in stores, SKU# 662536S.
Theory of Operation
The Bayou Jumper, like the Paraset that inspired its creation, utilizes very
simple and robust circuitry to achieve reliable operation. Despite this simplicity,
it attains the maximum of performance from its minimum number of
components, in the true spirit of QRP.
The transmitter design of the Bayou Jumper is borrowed from the 4SQRP
classic ‘NS-40’. This design is a master-oscillator/power amplifier circuit, with
high-efficiency spiral PCB coils serving as the transmitter’s harmonic filter. The
2N7000 Master Oscillator, Q5, works against the gate capacitance of the
IRF510 power amplifier, Q4, as an unusual inverted Colpitts oscillator. The
power amplifier Q4 is tuned to operate in the Class E mode, generating 5 watts
from 13.6 volts, at better than 85% efficiency. Closing the key contact grounds
the source circuits of Q4 and Q5 permitting oscillation to commence. If the
transmit/receive switch is in the receive position, closing the key permits the
Master Oscillator to oscillate without the PA operating, enabling spotting of the
oscillator frequency in the receiver.
A built-in key is included in the design –just like in the original Paraset!
Because the entire PA current passes through the keying circuit, it is
recommended, for those who want an external key, that the transmitter be
keyed through a hard contact closure, like a relay or straight key, or that a husky
MOSFET (IRF510 or larger) be used. See APPENDIX J for suggested circuits.
The receiver is a simple regenerative circuit, based on the innovative designs of
Charles Kitchin, N1TEV. Q2, an MPF102 JFET, is a regenerative detector in an
Armstrong circuit, with a 1N5819 diode acting as a varactor capacitor in the
tickler throttle circuit. The regeneration control, potentiometer R10, varies the
reverse bias voltage on the diode D2, changing its capacitance and varying the
amount of feedback current it passes through the tickler feedback winding of L1.

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 3 of 46
The receiver frequency is tuned by also using a reverse biased diode as a
varactor. The inductor L1 resonates against the sum capacitance of C20,
(optionally C20a) C30, and diode D3. Tuning is performed by potentiometer R8,
which varies the reverse bias voltage on D3, thus varying its capacitance.
The antenna is coupled to the detector through the grounded-base amplifier Q1,
a 2N3904. This amplifier also isolates detector oscillations, preventing them
from being radiated back through the antenna. An RF attenuator control, R1,
can be used to reduce the amplitude of strong signals that might overload the
receiver.
The detected audio appears at the source of the regenerative detector Q2, and
is coupled though capacitor C5 to audio preamplifier Q3, a 2N3904. Its output
is coupled to the volume control R6.
The output of the volume pot is amplified by the Audio Amplifier U1. This IC, an
NJM2113 is a low-noise headphone driver amplifier. Its balanced output feeds
the tip and ring contacts of the Headphone jack, J4. The shell contact is left
floating, placing the two headphone elements in series. This amplifier is also
capable of driving an external 8 ohm speaker.
A 6-volt regulator IC, U2, provides steady bias voltage to the low-level RF and
audio circuitry of the receiver, eliminating any tendency toward audio howl or
instability.
Switching between transmit and receive operation is performed with a rotary
switch SW1. This disables the receiver during transmit, and switches the
antenna between the transmitter and receiver sections. This switch also has an
OFF position, switching the antenna input to ground as well.
First Steps
Before getting started with building the kit, take some time to organize and
familiarize yourself with the parts provided and check them against the Bill of
Materials (pages 34 & 35). Building over a cookie sheet is recommended to
minimize the chance of lost parts. If parts are missing in your kit, send an email
to the kitter listed at 4SQRP.com. He will promptly provide replacements.

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 4 of 46
Schematics are provided separately as image files in the documentation
package, as well as being incorporated into this manual. It is highly
recommended that you 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.
It is helpful to acquire the necessary tools and supplies before beginning.
These include:
*Soldering iron –ESD safe, 20-30W, preferably thermostatically controlled.
*Small diameter (0.025” recommended) 60/40 or 63/37 rosin core solder
*Wire stripper
*X-Acto type hobby knife (#11 blade best)
*Diagonal cutters (flush-cutting type preferred)
*Needle-nose pliers
*Fine file or emery board
*Phillips screwdriver
*Allen wrench: 1.5mm –for the pointer knob’s set screw
*Hand drill with 1/8” bit
*Non-metallic alignment tool
*Fine jeweler’s screwdrivers
*Electrical tape
*Clear fingernail polish
*Wood glue
*Clamps or spring clothespins
*Magnifier
*Digital volt-ohm-meter
*Calibrated general coverage receiver, 40M CW receiver, or frequency
counter
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 filled the hole completely, and wicked up around the
component lead. Re-heat and apply more solder if necessary.

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 5 of 46
Enclosure
It would be best to prepare the enclosure before beginning assembly of the PC boards, in
case any minor sanding or filing were to be needed to refine the fit of the boards into the box.
The enclosure must be prepared to
mount the circuit boards. Included in
the kit are four 3/8” wooden blocks that
must be glued into the four inside
corners of the box. Use wood glue to
attach them (Elmer’s Carpenter’s Wood
Glue –the yellow kind). They should
be spaced down from the rim of the box by the thickness of two PC boards
(about 1/8”) – use the two crystal adapter boards as a thickness gauge.
After the glue has dried for several hours, place the top panel circuit board onto
the four corner blocks. Use a pencil to mark through the four corner holes in the
top panel board onto the corner blocks. Remove the top panel.
There are four wood screws in the parts kit for mounting the circuit board
assembly. If driven directly into the corner blocks, there is a risk the blocks will
split, so it is necessary to drill pilot holes for the mounting screws. Use a 1/8” bit
in a hand drill (or drill press if available), drill down approximately 1/2”.
Solder Filling Selected Vias
Vias are small plated-through holes that electrically join the top and
bottom copper layers of the circuit board. If you look closely at the heavy
traces near D1 and C22 you’ll see two groups of four vias in the middle of
those traces. These traces, and vias, carry the full transmitter current –a
substantial fraction of an ampere. To ensure a low resistance path these
eight vias should be filled, that is, enough solder should be flowed into
them that the solder is level with the via pads on both the top and bottom
sides. The same should be done to the vias at the center of each of the
etched inductors.
□Fill the four vias in the heavy trace near D1
□Fill the four vias in the heavy trace near C22
□Fill the three vias in the centers of the three etched inductors L3, L5, and L6

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 6 of 46
Preliminary Assembly
The large components (four potentiometers, BNC jack, and rotary switch) will be installed
first. In order to ensure that these components properly line up with the holes in the front
panel, test fittings will be performed.
□Locate the six 5/8” hex standoffs and twelve of the 6-32 x 3/8” machine
screws. Use six of the screws to install standoffs on the bottom side of the
Front Panel PCB at the six perimeter mounting holes (NOT the four corner
holes).
The first components to be installed on the Main PC board will be the four
potentiometers. R6, R8 and R10 are 50 k pots, marked “503” while R1 is a 5 k
pot, marked “502.” All four of these potentiometers will be installed “standing
proud” to ensure that there is enough shaft above the panel to accept the knobs
securely.
□Place the main PC board flat, right side up, on a hard
work surface, and insert the mounting tabs and pins of R8
(50 k, marked “503”) through the PCB mounting holes so
that the tips of the two tabs rest flush against the work
surface without extending past the bottom of the board. This
ensures that the shaft of the pot sits as high as possible.
Notice that when the two mounting tabs are flush with the bottom of
the board, the three contact pins will not quite penetrate all the way to
the bottom. This is normal and correct. The holes are through-plated,
and when soldered the connections will be solid.
□Make sure the pot shaft is vertical, and then solder only
one of the mounting tabs to the board. It will be easiest to
solder on the top side of the board.
□Place the front panel with its standoffs in position atop
the main PCB. Use three screws to temporarily secure the panel to the main
board. Inspect the alignment of R8 and make sure that the shaft can turn easily
without rubbing the sides of the hole. If needed, reheat the soldered tab and
reposition the part.

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 7 of 46
□Remove the front panel and set it aside for the moment. Do not yet solder
the remaining tab and pins.
□Repeat the above two steps for the other two 50 k pots, R10 and R6
(marked “B5 03”), and the 5 k pot, R1 (marked “B5 02”). Again, solder only one
tab of each part at this time. Check the alignment of each one by temporarily
replacing the front panel each time.
□When all four potentiometers have been partially installed, replace the front
panel. Secure it with all six screws, and make a final check of the alignment.
When you are satisfied with the positioning, remove the front panel and solder
the remaining tab as well as the three pins of each part.
Next the rotary switch and the BNC jack will be installed. Alignment of these
parts will be much more straightforward, since they will be firmly seated against
the PCB and should “auto align.”
You may wish to read the section in Appendix A concerning shortening the shaft of the rotary
switch. It’s only for appearance sake, to allow the knob to nestle down close to the panel. If
you decide to do this optional step, it is most easily accomplished before the switch is
soldered to the board.
□(optional) The shaft of the rotary switch is too long
to allow the selector knob to mount close enough to the
panel. Trim a bit off, but be sure that there is least ¼” of
the shaft remaining.
□The plastic index post is not needed and will
interfere with the front panel mounting. Nip it off with
diagonal cutters.
□ Install the rotary switch SW1. Be sure the nut on
the bushing is snugged up against the toothed lock washer. Do not over tighten.
Be certain that Pin 1 is inserted into the square pad marked “1”. The pin
numbers are molded into the switch body. Make sure the switch is fully seated
against the PCB and the shaft is vertical. Solder only one of the four inside pins
at this time.
Index post
Pin 1

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 8 of 46
□ Install the BNC jack in its location at the upper left corner of the PCB. Be
sure it is flat and flush against the board and is vertical. Solder only the center
pin at this time.
□Re-install the front panel and make another alignment check. Locate the
“chicken head” pointer knob and install it on the rotary switch’s shaft. You’ll need
a 1.5 mm Allen wrench to tighten the set screw. Check that the pointer will align
with the panel markings for the three switch positions. If all is satisfactory,
remove the knob and panel and set them aside. You may leave the standoffs in
position if you wish.
□Now solder all of the remaining pins of the BNC jack and rotary switch.
The leads of resistors and axial leaded inductors should be bent in a gentle
radius about 0.1” from the body of the part, so that the component body is not
stressed or broken. If you have a bending jig, use it, selecting 0.4” spacing for
all ¼ W resistors and diodes, 0.5” for L4, and 0.6” for L2. The bodies of these
components should rest flush against the board surface when mounted .
Inductors
There are two molded inductors that look like carbon
composition resistors. Add these next. Be especially
careful when bending the leads of these parts.
Notice the relative sizes in the photo.
The one with the larger inductance (L4 470µH) is the
smaller physical size.
√
Ref
Value
Marking
Description
L2
1.0 µH
Wide Silver-Brown-Gold-Black-Silver
Molded Axial Choke .6” LS
L4
470 µH
Wide Silver-Yellow-Violet-Brown-Silver
Molded Axial Choke .5” LS
L2: 1 µH
L4: 470 µH

revised 3 Feb 2021 Bayou Jumper revB Assembly Manual page 9 of 46
Resistors
Next, install these resistors, whose lead spacings may all be prepared as 0.4”.
Save a few of the discarded leads for use as test points and jumpers later on.
√
Ref
Value
Marking
Description
R16
100 Ω
Brown-black-brown
¼ W 5% axial
R17
1.0 k
Brown-black-red
¼ W 5% axial
R2
1.0 M
Brown-black-green
¼ W 5% axial
R4
1.0 M
Brown-black-green
¼ W 5% axial
R15
100 k
Brown-black-yellow
¼ W 5% axial
R3
2.7 k
Red-violet-red
¼ W 5% axial
R12
3.3 k
Orange-orange-red
1/4 W or 1/8 W, 5% axial
R7
3.3 k
Orange-orange-red
1/4 W or 1/8 W, 5% axial
R13
330 k
Orange-orange-yellow
¼ W 5% axial
R5
33 k
Orange-orange-orange
¼ W 5% axial
R11
470 k
Yellow-violet-yellow
¼ W 5% axial
R9
470 k
Yellow-violet-yellow
¼ W 5% axial
R14
470 k
Yellow-violet-yellow
¼ W 5% axial
R18
470 k
Yellow-violet-yellow
¼ W 5% axial
Special note for builders who intend to install a NA1MH Soup’er Up’er accessory board that is
described in Appendix J. That accessory is not currently available, but “previously owned” units
may show up from time to time.
You may wish to just tack solder R9 and C9 to the board in the upcoming steps, leaving extra long
lead lengths, since these parts will be subsequently removed after the basic checkout of the Bayou
Jumper, prior to installation of the Soup’er Up’er. Leave enough lead that they can be easily nipped
off and salvaged for the spare parts bin.