QRPKits Hendricks PFR-3B User manual

PFR-3B
Portable Field Radio
Figure 1
Specifications:
Bands : 40 meters, 30 meters and 20 meters
Tuning range: Full band coverage
DDS VF with 50 Hz slow tuning rate and 200 Hz fast tuning rate
Mode: CW only
Receiver MSD: 0.2 uV typical
Selectivity : 300 Hz
Four crystal IF filter and 600 Hz center frequency audio band pass filter
Receive current, no signal typical:
Display on, 47 ma
Display off, 34 ma
Transmitter:
5 watts at 12.0 volts, all bands +/- 10%
Transmitter current: 650 ma (40 M) to 750 ma (20 M) typical at 5 watts.
Spurs: - 50 dBc maximum, all bands
5 to 40 wpm internal B mode iambic keyer
Two (2) 63 character keyer memories.
Coax or balanced line output
Built in SWR indicator and BLT (balanced line tuner)
Size: 7.2” wide X 4.2” deep X 1.5” high (less knob height).
Weight: 18 oz, no batteries installed.
Power supply voltage: 8 volts minimum, 12.5 volts maximum. 12 to 9 volts recommend.
External power or internal battery pack
Pacific Antenna
www.qrpkits.com
Manual Revised: February 24, 2016

Assembly notes:
●There is no need to print out the whole assembly manual which would use up a lot of ink. Hopefully you
have a laptop or similar you can view these instructions on at the work bench.
●Do print the over all parts placement diagram to use as reference as you build. For experienced builders,
that is likely all you'll need for most of the assembly.
●re-sorting the resistors and capacitors can speed up the assembly and reduce mistakes.
●arts will be installed in order of height, starting with resistors. This way taller parts don't get in
the way had they been installed first.
●The placement diagrams highlight the parts to be installed. To reduce clutter on the diagram, parts
already installed or to be installed at a later step are not shown, with the exception of a few things
for reference.
●arts are numbered on the board starting at the lower right hand corner. Numbers run bottom to top, then
right to left across the board.
●Missing or lost parts? Contact QR KITS.com for replacements.

Figure 3

Table 1: Parts list
QTY VALUE QTY VALUE
1 10 ohms Brown, black, black, gold 1 4.7 p NP Disk, brown, black dot on top edge
1 51 ohms Green, brown, black, gold 1 22 p NP Disk, brown, black dot on top edge
3 470 ohms Yellow, violet, brown, gold 1 33 p NP Disk, brown, black dot on top edge
12 2.2 K, 1% Red, red, red, gold 1 47 p C0G
5 10 K Brown, black, orange, gold 1 68 p NP Disk, brown, black dot on top edge
3 22 K Red, red, orange, gold 7 100 p NP Disk, brown, black dot on top edge
2 47 K Yellow, violet, orange, gold 3 150 p C0G Mono, yellow
4 100 K Brown, black, yellow, gold 2 220 p C0G Mono, yellow
3 470 K Yellow, violet, yellow, gold 3 330 p C0G Mono, yellow
5 1 MEG Brown, black, green, gold 1 560 p C0G Mono, yellow
3 51 ohm 2W Green, brown, black, gold 1 680 p C0G Mono, yellow
1 10K audio Vertical PCB mount 2 470 p DISK Disk, brown
2 10 uhy rfc Brown, black, black, gold 5 .001 ufd disk Disk, brown
2 SA612AN 8 pin DIP IC 23 0.1 ufd X7R Mono, yellow
1 LM358N 8 pin DIP IC 3 0.01 ufd film Film
1 LM386N 8 pin DIP IC 1 30 p trimmer Green
1 74HC02N 14 pin DIP IC (74AC02 may be supplied) 3 Polyvaricons Polyvaricon capacitors
1 ATMEGA48 28 pin DIP IC 3 Polyvaricon hardware Screws and standoffs
3 1 ufd / 50V Aluminum electrolytic
1 78L05 T -92 5V reg 3 100 ufd /16V or 25V Aluminum electrolytic
1 78L06 T -92 6V reg 1 220 ufd /16V or 25V Aluminum electrolytic
4 8 pin DIP sockets
1 2N3906 PNP T -92 plastic 1 14 pin DIP socket
4 2N7000 T -92 plastic N M SFET 1 28 pin DIP socket
3 BS170 T -92 plastic N M SFET 2 FT37-43 Toroid Ferrite core, gray or black
1 FQP8P10 T -220 plastic P M SFET 6 T37-2 Toroid Powdered iron toroid (red)
1 1N4756A Larger glass diode, 47V 1W zener 2 T37-6 Toroid Powdered iron toroid (yellow)
1 1N5817 Plastic diode shottky rectifier, 1A 1 T106-2 Red Powdered iron toroid (red)
4 1N4148 Glass diode 1 12mm mechanical Encoder, w/switch, vertical mount
1 DDS module Built and tested. 1 6mmx13mm tack Push button switch, N
1 8 pin header strip Header for dds board 3 DPDT slide switch
1 4 dig LED 4 digit multiplexed display module 3 DP3T slide switch
1 Super bright Red LED (clear package) 1 DPDT toggle switch
5 4.9152 MHz Crystals Crystals HU-49US, matched 2 Stereo jacks 3 pin (no switch)
1 0.9 A hold, 1.8A trip PTC resetable fuse 5 Knobs 4 small, 1 medium
1 Power jack 2.1 mm pin 4 4 cell AA battery 2x2 holders and double sided tape
1 BNC jack Panel mount BNC with hardware 1 Red filter
2 Binding posts 1 Red, 1 Black 1 PC board
1 5 feet #24 hook up wire. 4 4-40 x 1/4” screws Socket with black plastic caps
1 5 feet #26 magnet wire 4 #4 lock washers Star washers
1 12 feet #28 magnet wire 4 4-40 x 1/4” screws Phillips pan head screws
4 Rubber feet Feet for case 1 Case Yellow case for PFR-3B

Figure 4: Resistors, diodes, RFCs
R1 10 OHMS BRN/BLK/BLK/GLD R25 2.2 K RED/RED/RED/GLD
R2 1 MEG BRN/BLK/GRN/GLD R26 22 K RED/RED/ORG/GLD
R3 2.2 K RED/RED/RED/GLD R27 2.2 K RED/RED/RED/GLD
R4 10 K BRN/BLK/ORG/GLD R28 51 OHMS GRN/BRN/BLK/GLD
R5 2.2 K RED/RED/RED/GLD R29 470 OHMS YEL/VOL/BRN/GLD
R6 2.2 K RED/RED/RED/GLD R30 1 MEG BRN/BLK/GRN/GLD
R7 2.2 K RED/RED/RED/GLD R31 470 OHMS YEL/BLK/BRN/GLD
R8 10 K BRN/BLK/ORG/GLD R32 47 K YEL/VOL/ORG/GLD
R9 2.2 K RED/RED/RED/GLD R33 100 K BRN/BLK/YEL/GLD
R10 470 K YEL/VOL/YEL/GLD R34 47 K YEL/VOL/ORG/GLD
R11 2.2 K RED/RED/RED/GLD R35 100 K BRN/BLK/YEL/GLD
R12 1 MEG BRN/BLK/GRN/GLD R36 470 K YEL/VOL/YEL/GLD
R13 1 MEG BRN/BLK/GRN/GLD R37 100 K BRN/BLK/YEL/GLD
R14 1 MEG BRN/BLK/GRN/GLD R38 2.2 K RED/RED/RED/GLD
R15 100 K BRN/BLK/YEL/GLD R39 51 INSTALL LATER
R16 470 K YEL/VOL/YEL/GLD R40 51 INSTALL LATER
R17 10 K BRN/BLK/ORG/GLD R41 51 INSTALL LATER
R42 2.2 K RED/RED/RED/GLD
R18 10 K BRN/BLK/ORG/GLD D1 1N4148 SMALL, GLASS
R19 10 K BRN/BLK/ORG/GLD D2 1N4148
R20 2.2 K RED/RED/RED/GLD D3, D7 1N4148
R21 2.2 K RED/RED/RED/GLD D4 1N5817 LARGE, BLACK LASTIC
R22 22 K RED/RED/ORG/GLD D5 1N4756A LARGE GLASS
R23 22 K RED/RED/ORG/GLD L1 10 uHY BRN/BLK/BLK/GLD
R24 470 ohms YEL/VOL/BRN/GLD L2 10 uHY BRN/BLK/BLK/GLD
Table 2

Figure 5: Capacitors
Since there are a lot of 0.1 ufd caps, these are highlighted in yellow. The rest of the assorted values are in
light blue. We will also install the crystals, highlighted in gray, and are mounted first. Solder a lead clipping
from the hole next to the crystal labeled “G” to the top of the crystal can to ground it. X1 is not grounded.
X1-5 CRYSTALS jumper case to gnd C21 101 (100 pfd) C42 102 (.001 ufd) DISK
C1 104 (0.1 ufd) C22 101 (100 pfd) C43 103 (.01 ufd) FILM
C2 104 (0.1 ufd) C23 101 (100 pfd) C4
4
104 (0.1 ufd)
C3 Electrolytic install later C24 104 (0.1 ufd) C45 104 (0.1 ufd)
C4 Electrolytic install later C25 101 (100 pfd) C46 104 (0.1 ufd)
C5 Electrolytic install later C26 101 (100 pfd) C47 Electrolytic install later
C6 Electrolytic install later C27 4.7 pfd DISK C48 104 (0.1 ufd)
C7 471 (470p) DISK C28 101 (100 pfd) C49 104 (0.1 ufd)
C8 102 (.001 ufd) DISK C29 151 (150pfd) C50 331 (330 pfd)
C9 104 (0.1 ufd) C30 104 (0.1 ufd) C51 221 (220 pfd)
C10 471 (470p) DISK C31 22 pfd DISK C52 151 (150 pfd)
C11 104 (0.1 ufd) C32 102 (.001 ufd) DISK C53 104 (0.1 ufd)
C12 103 (.01 ufd) FILM C33 Electrolytic install later C54 681 (680 pfd)
C13 104 (0.1 ufd) C34 102 (.001 ufd) DISK C55 561 (560 pfd)
C14 103 (.01 ufd) FILM C35 101 (100 pfd) C56 331 (330 pfd)
C15 104 (0.1 ufd) C36 104 (0.1 ufd) C57 68 pfd
C16 104 (0.1 ufd) C37 104 (0.1 ufd) C58 47 pfd
C17 104 (0.1 ufd) C38 102 (.001 ufd) DISK C59 33 pfd
C18 104 (0.1 ufd) C39 Electrolytic install later C60 331 (330 pfd)
C19 104 (0.1 ufd) C40 104 (0.1 ufd) C61 221 (220 pfd)
C20 104 (0.1 ufd) C41 104 (0.1 ufd) C62 151 (150 pfd)
Table 3

Figure 6: Most e erything else
Table 4: Parts should be installed in the order in which they are listed in the table below.
LED Display This will go in only one way as there are two missing pins and corresponding
pads.
U4,28 pin DI socket When installing sockets, double check the leads to make sure none of them are
folded over under the socket. This is very hard to fix once you start soldering!
U7, 14 pin dip socket
U1, U2, U3, U5, 8 pin
hone and paddle jacks Make sure they are set flush to the board.
R39, R40 and R41 51 ohm, 2 watt resistors Green/Brown/Black/gold
Q1 2N3906
Q2, Q3, Q5, Q6 2N7000
Q7, Q8, Q9 BS170
Q4 FQ 8 10 FQ 8 10, TO-220 Mosfet
U6 78L0 Check the number very carefully so as not to mix up with U8
U8 78L06
The electrolytic caps are installed laying flat to the board. The value indicated
on the diagram is in pfd. 10 = 1,000,000 pfd = 1 ufd
C4, C5, C6 (105) 1 ufd Aluminum Electrolytic. Long lead is plus, black stripe on can is negative.
C3, C33, C39 (107) 100 ufd Aluminum Electrolytic
C47 (227) 220 ufd Aluminum Electrolytic
When installing the switches, make sure the switch is set square to the board
before soldering more then one pin! If the switch is tilted, it may not fit into
the slot in the enclosure.
S4, S5, S6 D DT slide switch
S2, S3, S7 D 3T slide switch
S1 Long handled Tactile push button switch
ENC1 Mechanical rotary encoder.
V1 10K variable resistor.
D6 LED Space off board 1/4” to bottom of the LED.

Figure 7: Parts mounted on bottom of board
Several parts mount on the bottom of the board. These are the variable capacitors, the toroid coils, the BFO
trimmer and the resetable fuse.
Table 5
CV1, 2, 3 Mount these three variable caps to the bottom of the board, using the short screws supplied.
CT1 BFO trimmer. Make sure the flat side of the cap faces the line in the part outline, towards the
top edge of the board.
Fuse The outline is shown on the top side, but is mounted on the bottom.
Winding the toroids:
The wire needs to be wound snug to the core. A loose, sloppy winding job will result in poor performance. A turn
is each time the wire passes through the center of the core. Miss counting and having an extra turn is a common
mistake and will result in low power output.
Make sure you tin the wire leads before trying to solder the wire to the board! And make sure you don't pull the
wire through the pad past the tinned area of the lead. You can tin with your iron with a blob of solder at the
tip.
Table 6a: L6 – L14
L6 18 turns #28 (11”) on T37-2, Red core 40M
L7 21 turns #28 (12.5”) on T37-2, Red core 40M
L8 13 turns #28 (9”) on T37-2, Red core 30M
L9 18 turns #28 (11”) on T37-2, Red core 30M
L10 14 turns #28 (9”) on T37-6, Yellow core 20M
L11 18 turns #28 (11”) on T37-6, Yellow core 20M
L13 40 turns #28 (22”) on T37-2, Red core Rx in
L14 40 turns #28 (22”) on T37-2, Red core Rx in

Table 6b: L5 and T2 – These mount to the top of the board.
L5 8 turns #28 (5”) on FT37-43, black core
T2 25 turns #28 (15”) on FT37-43, black core. 5 turns #28 (3”) for primary. First wind the 25-turn
secondary. Then wind the 5-turn primary, in the space between the wire ends of the 25-turn secondary.
The 5T primary wires go to 2 center pads of the outline, secondary wires to 2 outside pads.
Winding and mounting of T1:
●Cut a 24” (2 foot) length of the # 26 wire.
●Wind 12 turns on the T100-2 core (this is the large red core)
●Start the winding of the core by passing the starting end of the wire into the hole from the bottom of
core. Wind the rest of the turns in a counter clock wise direction, passing the long end of the wire down
into the core from the top. Winding the core in this fashion will make the ends of the wire more or less
line up with the staggered holes in the board. Try to wind the wire fairly flat to sides of the core.
Space the turns so that they cover about ½ of the core. See photos at bottom of this page.
●ull the 6th turn on the outside of the core (counting from the left hand starting end) slightly away
from the middle, outside edge of the core.
●Scrape away the insulation on the wire of this 6th turn, near the middle of the core.
●Cut a 2” length of the # 26 wire and tin one end.
●Attach this wire to the 6 th turn on the core. Make a small, half loop on the end of the wire and lightly
crimp to wire on core, then solder.
●Cut an 18” length of the # 26 wire and wind 6 turns inter-weaved between the first winding and centered
around the tap you just made, so there are 3 turns on each side of the tap. It is easiest the start the
winding of these turns from the center tap of the first winding.
●Now cut an 8” length of the # 26 wire and wind 1 turns on each side of the tap, for a total of 2 turns.
This winding will also be inter-weaved between the other two windings.
●ush the windings together so they are close to each other and not spaced around the core.
●Before mounting T1 to the board, solder in the wires which will connect to the binding posts into the
holes labeled “B ”. (4.5” long) These wire will pass through the center of the core. If the wires are not
installed now, it is difficult to do once T1 is mounted in place.
●The core is mounted to the bottom of the board, the wires are soldered from the top. Suspend the core
slightly off the bottom of the board so the wires do not touch the ends of the switch mounted above it.
The thick magnet wire is difficult to tin properly, verify connections were made with an ohm meter.
DDS Module:
The final step is to install the DDS module. This gets soldered in place as there isn't enough “head room” for a
socket. The module is installed on the top side of the board and can only go in one way. Once soldered in place,
clip the SI pins flush to the board. If they are not trimmed back, they may short to the batteries in the
internal battery pack.
Figure 8b: T1 with HI-Z and
LOW-Z winding
Figure 8c
Figure 8a: Primary winding of T1
with center tap
Figure 9: Winding T1

Testing and calibration:
The board is now complete except for installing the ICs. Give the BFO trimmer (CT1) about a ¼ turn from its
factory setting. If you look closely in the trimmer hole, you will see an arrow at one end of the screwdriver
slot. When the arrow points towards the flat side of the body, it is a maximum capacitance. When it points to the
round end opposite the flat end, it is at minimum.
If you have some 1/2” 4-40 screws and nuts or threaded spacers, put these in the four corner mounting holes to
rise the board off your bench. Otherwise, clean the work space of wire clippings and solder blobs. Wire up the
power jack and BNC jack to the board. Wrap a piece of tape around the leads of the power connector so there isn't
a chance the B+ can short to something on the board as you flop it around to work on.
Initial tests:
Connect a 9 to 12 volt power source to the board and use the power switch on the board to turn it on.
●Check for proper voltages from the regulators. There should be +5 volts on pin 14 of U7 and +6 volts on
pin 8 of U5.
●If the voltages are correct, disconnect power and install the MEGA48 processor into the U4 socket.
●ower up the board again and the power up sequence should be seen on the display. 1) all segments light
for a second, 2) 40, 30 or 20 will be shown depending on which band the band select switch is set to and
then 3) the initial operating frequency.
●You can now test the tuning and Menu switch for proper operation. Refer to the operating instructions.
●Remove power again and install the rest of the ICs.
●U1, LM386 / U2, LM358 / U3, SA612A / U5, SA612A / U7, 74AC02 or 74HC02
●Connect an antenna to the BNC jack and restore power.
●You should now be able peak the receiver input tuning and to hear stations. (Attach the nylon spacer
shaft extender to the variable cap to make it easier to adjust.)
Transmitter testing:
Turn the power off and then disconnect the antenna and connect up a suitable QR power meter and dummy load. Make
sure the TUNE / Operate switch is in the Operate position and the coax / BLT switch is in the Coax position.
lug in a paddle or straight key. If using a paddle, you can hold the dash paddle closed when turning the power
on to set the rig to straight key mode. Then the dot paddle will key the transmitter on and off.
You can now turn the power back on and key the transmitter. ower output depends on supply voltage. With a 9.0 V
supply, power out should be about 2.5 watts on all bands. With 12.0 V supply power out should be between 4.5 and
5 watts on all bands.
Tweaking power output:
ower output is affected by the spacing of the turns on the input side coil for the low pass filter. This would
be L6, L8 or L10 for 40, 30 and 20 respectively. If power output is too high, move some of the turns closer
together. If it is too low, spread the turns out as best can be done. If the power out is much lower then
expected, this is usually due to have an extra turn on the core or a very loosely wound one. Although some times
the problem is simply a power meter which is not very accurate at these power levels.
SWR bridge testing:
Set the TUNE / Operate switch to TUNE, disconnect the dummy load and transmit. The LED should light brightly. Now
reconnect the dummy load and transmit again. The LED should be off or very dim.
BLT testing:
The Balance Line Tuner is more easily tested once the board is wired up into the enclosure, but you can do that
now if you like. If there is a problem it will be easier to fix with the board out of the case.
First install the wires to the board to the output of T1 which will connect to the binding posts. Now connect the
BNC jack to these wires. It doesn't matter which one is ground. Attach the shaft extenders and knobs to the
variable caps to make then easier to adjust.
Connect your dummy load and also your power meter if you like. Set the Tune/operate switch to Tune and the
Coax/BLT switch to BLT. Set the Hi Z/ Low Z switch to Low Z.
Refer to the operating instructions later in the manual for how to use the BLT. Tuning is very touchy and it
takes some practice. Doing this now into a dummy load is a good way to not only verify operation, but to get that
practice.