Description and notes
The Icom IC-718 is a nice, relatively small and compact transceiver. It may have some sick things, like bad AGC in SSB, big steps in volume control at low levels or very noisy receiver. But overall, it is a very nice transceiver for it’s price.
Prerequisites for adjustments
Check, that the voltage is 13.8V even when transmitting. Measure at the external DC input at transceivers back. Open the transceiver carefully, and put it on the side, so you can access both sides, top and bottom.
Power adjustment (all)
On the main board, locate the R1707. It is responsible for the output power. You can, but should not, go up to 200W out on SSB/RTTY/CW. But you should keep things cool and the DC voltage stable. At some point there may be a saturation point, you can raise up the DC voltage up to 14.4V to get more power or to overcome the saturation.
Power adjustment (AM)
Also on the main board, locate the R1730. Set it for no more than 50W AM carrier. More will not only work badly, but also produce much more splatter.
First IF-Mixer balance
Turn the transceiver to the frequency of 100kHz. Connect RF voltmeter to pin 12 of ACC connector for TNC and adjust the resistor R1104 until the minimum level on the voltmeter scale. This resistor is located inside a soldered box on the main board.
IF-Gain (more dynamic)
On the main board, there is R1614 which controls the overall IF amplification. Locate an very weak station on 80m. Switch the preamp and ATT off. Then adjust the R1614 for the best signal to noise ratio.
Speech compressor adjustment
To adjust the speech compression level adjust the R2220 on the main board. This adjustment is not described in the service manual, so have something to check the compression levels and also maybe an spectrum analyser to check for unwanted splatter.
Final S-Meter adjustment
After all adjustments, there is need for realignment in the service menu, at least the S-Meter. You should have a standard signal generator for this, or any other signal source able to put out signals in 20m band with the levels of S0, S9 and S9+60.
Last updated on 2022:12:05 at 01:47 UTC