Specifications

2. Reinstall the crystal directly across the base of the oscillator “K”
and ground. The simplest way is to first splice some short bare
wires to its leads so it will reach the proper PC foil pads. Then lay
it down flat on the solder side of the PC board and solder to the
PC foil pads. Use electrical tape under it to prevent shorts.
Alternately, you could also mount it vertically on the parts side of the
PCB. This means drilling two very small holes in the PC board. You
can use a #58 drill bit, or a #105 or #106 Dremel bit. Try to find a
PCB spot where you only have to drill through the fiberglass. If you
must drill through a foil, pick a wide one, like the common ground.
Then scrape out an extra 1/8" around each hole to prevent shorts
when you pass the spliced crystal leads through the drilled holes.
Recheck for any possible shorts from the crystal leads to the PCB foils.
EXPANDER 160 PREPARATIONS
1. Jumper for the SWITCH mode, even though you will actually use
the OSCILLATOR mode. Remove jumpers J4, J5, J6, and J7 and
install jumpers J1, J2, J3, and J8. Install a wire in hole “A.”
Ignore hole “B.”
2. Connect the loose end of the “A” hole wire to the top lead of the
4.7 µH RF choke you installed in Step 1 of the preceding section.
3. Remove capacitor “E” (5 pF) from the radio. Connect the
YELLOW “RF” wire to the empty hole going to the base of
transistor “E.” Keep this wire very short; 3" should be plenty.
This completes the installation. If you check the radio schematic and
the sketch below, you’ll see that you’re now using the existing
Clarifier circuit to slide the cold end of the EXPANDER 160’s crystal
bank. The radio’s 10.240 MHz PLL oscillator is still functional. But
now you’ve removed the “K” mode offsets and have added your own
Clarifier tuning. The “I” offsets are the only frequency adjustments
you’ll need besides each crystal trimmer in the EXPANDER 160.
You can power the EXPANDER 160 from the same source as the
Clarifier (point “J”). Ground the BLACK wire by soldering to the
closest metal transformer can. Keep the YELLOW “RF” wire very
short You can mount the unit along the PLL side of the radio frame
using a small L-bracket.
ADJUSTMENT & OPERATION, µPD2824 SSB MODELS
A Frequency Counter or second SSB radio is required. Ignore any
alignment instructions for the “K” coils, now out of the circuit. Set
the Clarifier to the 12:00 knob position and adjust the AM “I” coils
and crystal trimmers for the center channel on each band. (26.955,
27.405, 27.855 or whatever in the Ch.40 position.) By using a
second SSB receiver with known accuracy and its own Clarifier at
12:00, you could then set the USB/LSB coils for the most natural
voice sounds, without even needing a Frequency Counter. Use the
best combination of adjustments you can find, consistent with good
Clarifier range and knob symmetry.
Adjust VCO coil “F” to cover the desired range. In most cases the
maximum range is 160 channels before the VCO quits. Adjust all “L”
RF coils for the most even RF power output across the desired range.
RX sensitivity is usually OK as is, with no further adjustment needed.
NOTES
1. Slide range varies from chassis to chassis and also depends upon
crystal load capacitance. (Don’t exceed 20 pF when ordering.)
You may get a case where there’s only about 2-3 KHz USB up-
slide with the Clarifier knob fully clockwise. To cure this, decrease
the value of USB capacitor “I” by about 20-40 pF; this raises the
USB frequency and makes the Clarifier tune in more closely to the
center position. If you need still more range, try screwing the slug
of the USB coil “I” all the way down to minimize its inductance.
2. You can sometimes boost the slide range by increasing your RF
choke value from 4.7 µH to 10 µH maximum. Don’t exceed this
amount!
Before bolting the EXPANDER 160 to the radio frame, secure all
adjustments and critical VCO parts. You can use an ordinary candle,
dripping fresh wax around the VCO parts as well as the Clarifier
varactor diode. In a pinch you can use your wife’s fingernail polish,
but it’s harder to remove if you must retune. This circuit area is
extremely sensitive, and must be mechanically secure from vibration or
you’ll drift all over the band!
Good DXing!
NOTE: For chassis not included here, send a large #10 stamped self-addressed envelope and the exact radio make and model number. We’ll try to
help.
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EXPANDER 160 PAGE 8