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Mods - SV3EAO Icom 775 4.5 kHz eSSB
Modifications for Transmit and Receive

SV3EAO Icom 775 4.5 kHz eSSB Transmit / Receiver Modifications

Icom 775

Disclaimer Notice:

The following modifications were obtained from credible sources and should be done by qualified personnel at the owners risk. I am not responsible for any damage to, or illegal operations of the equipment as a result of mod errors or possible mod misinformation via this page.

Icom 775 Mods - Courtesy of SV3EAO - Fotis Visilias
(Enlargable Photos At Bottom Of Page)

  • First of all the mod takes place only on the component's side of pcb.

  • The diode in the black image is 1N 4148 and the parallel capacitor is a 10nf (use plastic or polyester).

  • The switch is on-off type. The relay is a small type PCB 12V like Omron or anything with the same contacts.

  • This is useful if switching between 2.kHz and 4.5Khz needed.

  • If you want to fix the BW at 4.5khz without switching, you must connect the P4 with P3 with a piece of wire.

  • You must cut the PCB points like the photo, but leave the P1,2,5,6, without connections.

  • This mod bypasses the Hi-cut and Low cut of the DSP unit, no matter what crystal filters you use, because the Icom's PSN modulation take place outside of them when the radio is on TX.

  • On RX, the received signal passes through the crystal filters, so the BW depends on them first.
    If you are using the standard factory 2.8 kHz crystal filters, there will be no difference on receive after the mod.

  • But on TX the difference is fantastic!!!

  • On the menu settings, the DSP and PSN must be turned "ON".

  • The DSP unit is on the upper side of the radio. Is a vertical PCB at right of the internal speaker.
If someone wants to experiment or try something better, I have the radio's service manual and will entertain any ideas with pleasure. I believe that the radio can TX out to 6 kHz BW, but I haven't found free time from my QRL to check it.The overall BW depends is dependent on the DSP unit only and the block diagrams is- [AD converter, to limiter, to lowcut, to hicut, to line pre, to DA converter.]

For further information or details:


73, Fotis Visilias - SV3EAO

Photos For Above Mods: Coutesy of SV3EAO - Fotis Visilias

Click on Photo to Enlarge:

Icom PCB-1

Icom PCB-2

John M. Anning - NU9N e-Mail:  e-Mail NU9N
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