A cheap speech compressor for the FT-818ND and an expensive DSP.

Shortly after acquiring my FT-818ND I had a bunch of mods for it that I wanted to perform. I’ve had one once before and wasn’t really happy with the speech output on SSB, and the lack of DSP was annoying.

So I had a look to see if the “One Big Punch” mic mod was still available, and alas it’s not. It seems that W4RT electronics that used to sell all things radio have since vanished into the ether – not entirely uncommon in this hobby. So I had to look for something in it’s place.

I eventually stumbled across some forums that had eluded that the SSM2167 module might be a suitable replacement. They’re nice and cheap and easily sourced from ebay and most importantly they’re small – small enough to fit inside the MH31. The unit only needs 5v to run and the MH31 has a 5v supply in it that’s not used. I had a quick look on ebay which returned lots of overseas listings, I eventually went for the one linked below.

https://www.ebay.com.au/itm/183649194369

It came from overseas as there was nowhere in Aus that I could find local stock, and took about 3 weeks to arrive. When it arrived I set about opening up the mic and installing it, I’ll let the pictures do the talking here and show you how I installed it.

The process goes something like this:
– Open the mic up
– Figure out where I’m going to put it
– Remove the two speaker wires (White is hot and Brown is shield)
– Solder in the output wires and the power wires to the SSM2167 board
– Solder the two speaker wires into the input on the board
– Solder the output wires onto the original pads for the mic
– Source a Ground pad nice and close to the mic
– Figure out which pin provides the power to borrow to power the module
– Put back together, dial SSB gain back and test

All in all after I put it back together I fired up the radio and I’m seeing a solid 4-5 bars of modulation on the output meter with the SSB gain set to 75. Previously it was on 100 and it was struggling to get 4 bars. I’m yet to have a decent QSO with someone else to dial the gain in nicely, but it’s a pretty cheap mod for those wanting to get a bit more boost out of the stock mic without changing the insert over.

This is actually only a short term mod for me, as I have the BX-184 on the way which will completely replace the internals of the mic – mainly for the voice keyer so that I’m not wearing out my voice when calling CQ from a park or a summit.

Oh – I also installed a BHI NE1901-KBD module into the radio – but there’s plenty of info out there on this mod so I didn’t document that one for the blog. I’ve not had one before but my only comments would be this:

The DSP is slow to kick in after releasing the Tx button – careful where you set that volume knob
The default mode of the DSP is OFF when you turn the radio on – it would be nice if it remembered where it was when you turned it off (It does remember the set level though)
The “Beep” jumpers don’t change the volume of the startup beep
It’s good at reducing background noise in high-noise environments (I have a S9/S9+ noise floor at home on 40m) but it won’t pull a “just barely there” signal out of the noise. It will however take a signal that’s a difficult copy and make it a less-difficult copy in high noise environments
The input level REALLY needs to be calibrated – RTFM (I’ve had my radio open and closed again 3 times after installation to get this right)
I wouldn’t consider the install once for beginners. If you haven’t got a good temperature controlled soldering iron, and experience with fine soldering – outsource the mod to someone else.

Hopefully this one is useful

73 – Josh – VK2MES