CW filters in SSB modes (Transceiver ICOM 746)
If you want to work on digi modes and have an ICOM IC-746 (perhaps also IC-756), you can arrange your CW filters so than can be used for SSB reception (LSB for Hellschreiber, USB for PSK31). You will improve IF parameters also for CW and RTTY. In the principle you must to say to transceiver that CW filters are narrow SSB and set your PBT for best IF bandwith. Best results we will get with maximal possible filtering:
| Position | 9 MHz - 1 | 9 MHz - 2 | 455 kHz |
| Installed filter | FL-232 (350 Hz) | FL-101 (250 Hz) | FL-53A (250 Hz) |
| Marked as in setup (1) | FL-232 | FL-223 | FL-222 |
| Marked as in setup (2) | FL-232 | FL-223 | FL-53A |
Combination (1) is good for PSK-31 and HELL as preferred modes (see pictures below).
| Mode | Filter 9 MHz |
Filter 455 kHz |
| LSB | 2.4 k |
2.4 k |
| LSB-N | 1.9 k |
1.8 k |
| USB | 2.4 k |
2.4 k |
| USB-N | 1.9 k |
1.8 k |
| CW | 350 |
2.4 k |
| CW-N | 350 |
1.8 k |
| RTTY | 2.4 k |
2.4 k |
| RTTY-N | 350 |
2.4 k |
Combination (2) is perfect solution for CW/RTTY DXing and contesting as well.
| Mód | Filtr 9 MHz |
Filtr 455 kHz |
| LSB | 2.4 k | 2.4 k |
| LSB-N | 350 | 2.4 k |
| USB | 2.4 k | 2.4 k |
USB-N |
350 | 2.4 k |
CW |
350 | 2,4 k |
CW-N |
350 | 250 |
RTTY |
350 | 2.4 k |
RTTY-N |
350 | 250 |
PBT is set to: inner 2 points left or to center, outer 2 points right from center position.
Mark RTTY is set to 1615 Hz.
Results are showed on the next pictures which are given with Spectrogram vers. 5.0 - freeware from http://www.monumental.com/rshorne/gram.html.
Picture 1 - LSB (Hell), narrow band, center frequency 980 Hz
Picture 2 - USB (PSK31), narrow band, center frequency 2000 Hz
Picture 3 - SSB, wide band
Picture 4 - CW, narrow band
Picture 5 - CW, wide band
Picture 6 - RTTY, narrow band
Picture 7 - RTTY, wide band
