ILER-20 MK2 SSB QRP Transceiver Kit
Page 26
Terminals “ATT” for enabling the RX attenuator
The header pins labeled “ATT” (located in quadrant D-10) can connect to a simple switch to activate the
receive attenuator.
The attenuation level is inversely proportional to the value of R1, which takes a part of the signal from
the antenna to ground. As you use the ILER-20, you may decide that you prefer a different level of
attenuation; simply replace R1 with the next value above or below that of the current resistance,
according to your wish.
The receiver can operate perfectly without using terminals “ATT”; however, it will not be able to reduce
the signal of the antenna input to compensate for very strong signals, and consequently it might produce
intermodulation distortion due to saturation of IC2.
If you frequently use the ILER-20 at different hours of the day and night, it might prove useful to add a
potentiometer for “RF Gain” at the terminals “P1RXG”, with which you can adjust the attenuation level at
the RX input according to what is most appropriate for each situation.
Terminals “P1RXG” for connecting a RX attenuator potentiometer (optional)
The header pins P1RXG can connect to a 1K linear potentiometer for adjusting to the most appropriate
attenuation level at the moment. This potentiometer is optional and is not included with kit. For
connection details, see the corresponding Appendix in the additional documentation.
If not using the P1, remember to place a “jumper” (bridge) among active terminals.
Terminal “K1” for carrier generation
The header pin marked "K1" is located in quadrant D-6.
This terminal is provided for generating a carrier for testing, transmitter adjustments, adjusting antenna
couplers, etc. It can also be used to operate the ILER-20 in CW mode (see Appendix in the additional
documentation).
Connecting terminal K1 to +V during transmission, unbalances the modulator and a carrier is generated.
Terminal “K2” BFO offset for CW (occasional)
The terminal marked "K2" is located in quadrant L-4.
This terminal is provided to shift the BFO during transmit by several hundreds of Hertz to use the ILER-
20 in CW mode. To operate in CW, the K2 terminal stays connected to +V during RX and is
disconnected during TX (see Appendix in the additional documentation).
Important:
- Note that to operate in CW mode, the switching of K1 and K2 connections operates opposite each
other. For more details, see the corresponding Appendix in the additional documentation.
-
The ILER-20 is not specifically designed for operating in CW.
However, K1 and K2 allow CW
operation on an occasional basis, for tests or in case of emergency.
- To operate only in SSB, no connection to K1 or K2 is necessary.
- All of the adjustments mentioned in this manual are for operating
in SSB.
