The
Rockless QRP
Circuit Board Assembly Hints
(NOTE: Always confirm component values before installing on Circuit Board)
Assemble the
VFO Board First:
1. Carefully mount all parts. Watch polarity of the Varactor
Diode.
( Flat side faces the green
trimmer capacitor). Also make sure the
exposed lead from the trimmer goes to
the grounded solder pad.
2. Visually inspect for shorts, etc
– use magnifying glass.
3. If
using the 10 turn potentiometer, temporarily connect leads to it
from the potentiometer terminals
on the VFO board.
4. Set up 12V supply in series with a
millimeter. Set for 100 ma. scale.
5. Apply voltage to board. Current
should be about 14-16 ma.
(If you get a sudden high
current immediately remove power and
inspect for solder overflow or a
reversed diode)
6 Check that you have about 6V at the 6
volt zener and 9V at the 9 volt
zener diode junction.
7. Listen on a communications
receiver in low end of 40 meter band.
8. Turn tuning potentiometer all the
way left (lowest freq)
9. Find signal on communications
receiver – it may be out of band.
10. Adjust trimmer until you get lowest
desired frequency above 7.000Mhz
(This
adjustment is touchy – be patient, and move bit by bit.)
11. Turn tuning control to right to see
that frequency moves up and
how far up the band based on the resistor
in series with the low end
of the
control. With 10K you should tune up
about 100KHz. from
where
you set the lowest frequency with the trimmer.
Assemble the
Main Circuit Board:
1. Mount the three IC holders. Note
the dot and number 1 pin go
to the left when looking at the
top of the board with the torroid
on the rignt top. Immediately
use an ohm meter to check for shorts
between any of the socket pins.
2. Wind the torroid coil and mount
it. Mount the trimmer and the
180 pf capacitor. At this point one can temporarily insert a
1500
ohm resistor in the Mixer Chip
socket at pins 1 and 2, and with a
VSWR analyzer connected to the
coil link, adjust the trimmer
capacitor for resonance at about
7.050 MHz.
3. Now proceed with installing
components in the upper part of the
board. Carefully note that you have 4.7K
resistors where needed and
not 47K. Also beware that the 1 Meg. resistor and 510
ohm have
similar colors but in reverse direction.
Make sure R4 is 1 meg. The
receiver will not work if R4 is
a low value.
4. Proceed with installing all the
solder-in passive components
5. Install the 5 volt regulators, but
not the transisitors at this point.
6. After all components except transistors
and IC’s are in place, apply
power to the board using the milliameter
in series with the supply.
Current should be about 14 ma. . Now
check for 5 volts at the two
voltage regulator zenor diodes.
7.
If all looks good solder in all transistors and put IC’s in socket.
8.
Again apply power and current should be
around 30 ma.
9. Now install the two board jumber
wires – one for receiver RF injection,
and
the other for keying the transmitter from Q2 a 2N7000. (See the
jumper wire drawing in your drawing package)
10.Solder in all wires for external connection
to volume control, key and
receiver audio. (See Drawing Showing
Connections)
Preliminary
Testing:
1. Connect the VFO to the Main
board. (rf in, ground, +12.V ). There is
a soldering pad on the main
board to pick up 12V. for the VFO.
2, Put a 50 ohm load on the antenna
terminals. If you have an RF probe
or low power watt meter connect
it to the antenna.
3. Apply power to the assembly. Standby
current should be about 40 ma..
4. Key the transmitter. Current should
go over 100 ma. Check for RF
output on the probe or
wattmeter.
5. Monitor transmitter in your
communications transceiver for tone and
frequency.
6. If you have a signal generator,
hold the output near the torroid and see
if you hear audio in the
phones. Also check that the Green Led goes
on and off with keying and with
activation of the switch button.
7. Connect to an antenna and see if you
hear 40 meter cw signals.
8. If all checks out well, you are
ready to install the boards in the housing.