TS-830s Audio Modification

To get compression, many DX operators run their mic gains so high that you can hear the breaths they take between syllables as clearly as their voices. Albeit an extreme case, to lesser degrees we find this audio artifact prevalent on the HF bands. If you want to extend control over your transmitted audio without going the eSSB route, you might want to consider adding this little box to your station for about $40. 

Adding a downward expander cleans up your transmit audio.

The SSM2216 processor chip is used in many devices, from guitar boxes to W2IHY products. It includes a downward-expander which eliminates breaths from your transmitted audio. You can get the chip and circuit board for $25. This mod enables you to reduce the sensitivity of your microphone without lowering the drive to your rig. 

The Hershberger® Speech Processor
Used by W1ZY in Kenwood Hybrids

It does this by tasking the MIC GAIN to set the audio drive to your transmitter while the controls on the processor box set the sensitivity of your microphone. The balancing act between the two enables you to eliminate background noises, including your breaths, from your on-air audio., Thus you are able to sculpt punchy DX audio with the box and then set the level at which this audio modulates your rig with the MIC GAIN control.

TS-520 Front Panel Modification
Speech Processor Controls

This is the second install of the SSM2166 processor into a Kenwood hybrid radio, the first being an involved affair requiring the removal of a TS-520's ront panel to fit the processor's four (4) potentiometers under its S-meter. The second installation places the processor chip inside an external box so that it can be used with a TS-830s donated by Steve, K2IL, in Florida. Details of its repair and alignment can be found elsewhere in this blog.

The enclosure is an electric guitar effects box procured on the internet. The chip is powered by a 9 Volt battery inside the box so that it can be used with any rig. Before getting into the install details, let's identify the sources of the components you'll need to perform this mod.

You can get the SSM2166 chip from Small Bear Electronics in Brooklyn, NY for $12. Remember, this is the same chip used in many W2IHY products, and costs as much as a 12-pack of beer. To save on shipping costs, look for components you'll need for this project on the Small Bear web site when ordering the SSM2216 chip--especially the four (4) potentiometers which need to be PC-mountable in order to ease installation of the circuit board into an enclosure. 

SSM2166 Chip ($12)

SSM2166 PC Board $12

You will also need the PC board that configures the chip as a speech compressor and downward expander. This is available from AmzFX for $12.

I was motivated to mod the TS-830 when I noticed the large, blank space on its rear panel on the other side of which lay the rig's power transformer--the worst place to bring in audio lines. Nevertheless, this empty space appeared to be calling for the installation of a die cast Bud box fitted with XLR audio connectors. Having no Bud box on hand, I cut a hole and mounted several RCA jacks. This plate of jacks will be replaced by a Bud box from which I will route audio cables through the hole into the rig.

Template for Hole

A template of the RCA plate was composed on graph paper, cut out and taped to the rear of the rig. Quick work with a Dremel produced a jagged hole rendered smooth with a few strokes of a hand file. Total time: 5 minutes. 

TS-830S Audio Ports

The RCA panel was mounted with machine screws, two of which being run down on the other side by standoffs to accommodate the mounting of a perfboard containing an isolation transformer and attenuation pad needed for this mod. We knew the isolation transformer would probably couple with the power transformer, but did it anyway to keep moving along.

 

Mod Final Location

Naturally, the coupling between the two transformers was so great that the perfboard was relocated to the IF board, mounted above it off two standoffs next to the spot where the microphone cable (MV1) is wired into the rig, This was a perfect place; there was no more hum in the transmit audio. And that's it for the machining needed for this mod.

Parts List
SSM2166 Compressor/Downward-expander

Wiring It Up

Rear of Mic Connector.

First, desolder the shielded microphone from the rear of the microphone connector mounted on the front panel of the rig. This cable leads to the mic-level input to the rig's microphone amplifier ("MV1"). Connect it to the output of the attenuation pad on the perfboard. Solder a shielded cable from the two empty pins on the mic connector and run to an RCA jack (MIC OUT) on the rear of the rig. This passes the audio from a microphone connected to the rig to a RCA jack on its rear panel while maintaining PTT functionality of the microphone. This RCA jack (MIC OUT) connects to the input of the processor box. 

Solder another shielded cable to an RCA jack on the rear panel, label it "AUDIO IN", and connect it to the primary of the isolation transformer on the perfboard. This RCA jack will be connected to the output of the SSM2166 processor box when you cable this thing up. We placed a 20 dB attenuation pad between the secondary of the isolation transformer and the microphone input of the rig (MV1) to be able to fine-tune the level of the incoming audio down to mic-level. Interestingly, this pad's design is based on a TS-830S modification presented by Kenwood to create a "phone patch" input to the rig. 

Perfboard Mounted Above IF Board
Contains isolation transformer and attenuation pad.

We modded their mod by adding a 100K trimpot for reasons already described. Remember, connect the output of the attenuator pad to the red microphone cable (MV1) which you initially desoldered from the microphone connector. This concludes the wiring requirements of this modification. 

Cabling up is a snap, requiring two everyday RCA patch cables. One goes from MIC OUT on the rig to the input of the processor box. And the other one goes from the output of the processor box to the "AUDIO IN" on the rig. NOTE: You can add additional devices--like an equalizer--between the output of the processor box and the rig if you want.

Realigning ALC and RF Speech Processing Circuits
Although this mod will work as is, you can really dial it in by recalibrating the ALC and RF speech processor stages in the TS-830. This mildly complicated procedure equalizes ALC meter deflection between unprocessed and processed states, and allows you to determine where ALC deflection begins on the MIC GAIN knob. There is no need to perform these calibrations after installing this modification. We only mention it to alert technically-minded readers of its possibility. The only reason I did it on the TS-830S is because, at the time, I was realigning the whole rig after repairing it. 

Fully-assembled SSM2166 processor boxes are available at an exorbitant price. 


BILL W1ZY

PHOTO GALLERY