ILER-20 MK2 SSB QRP Transceiver Kit Page 29
2) The most effective and cleanest option is t o use a small plastic tie-wrap, passing it through the
holes in the circuit board as showing in the picture.
Once the tie-wrap is f ully tightened, you will still be able to move the turns slightly and make slight
adjustments before securing them with a little bit of nail polish.
L6 should be well secured; this is very important, since vibrations may change the VXO frequency,
causing frequency "flutter" in the received and transmitted signals.
IMPORTANT: Prior to permanently securing L6, make all of the transceiver adjustments and checks and
confirm that the frequency coverage suits your needs.
I r ecommend this number of turns and type of toroid for L6. It works well! However, you can modify and
experiment with the inductance to try a different coverage. More inductance will increase the coverage
but reduce the stability and the VXO may even stop oscillating, and vice versa.
In order to obtain good stability, a maximum coverage of 50-60 KHz is
recommended.
In addition, a wide coverage will make tuning difficult, and it will be necessary to add a fine tuning control
by using gear reduction on the polyvaricon, a second variable capacitor or a varactor diode.
Do not worry too much about obtaining exact coverage down to the KHz. I s it so important to end up with
60, 59 or 61 KHz?
If you have graphical ability, you can draw a dial on the front panel with a frequency scale to serve as a
guide.
In order to put us in other segments of the band different from t hose specified here, you will need to use
VXO crystals with different frequencies.
Adjustment of the BFO/Carrier Oscillator
There are two ways to adjust the BFO oscillator frequency.
- Adjustment without instrumentation:
Turn on the transceiver. Leave it on for about 5 minutes.
You can adjust CV1 while listening to a USB signal on the 20 meter band. This is a “two-hand” operation;
tune the VXO to obtain the best possible intelligibility, and next adjust CV1 to obtaining the best possible
audio quality. Repeat these adjustments until obtaining the best possible results.
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