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N8YX
12-19-2010, 03:13 PM
Are you a proud owner of an IC-R7000 receiver which has no voice synthesizer installed?

Do you wish it had a little more in the way of selectivity and noise-fighting features, a la its later siblings the R8500 and R9500?

Fret not. There's a mod(ule) for that.

Disclaimer: One could always plug a Timewave DSP-599 into the '7000's Speaker Out jack, but the following solution is about half the the price...and goes everywhere the radio does.

SGC makes it: http://www.sgcworld.com/ADSPProductPage.html

Those wishing to duplicate my efforts will want to order the "low" module. The "high" unit has an onboard audio amp, and it isn't necessary for this application.

Examine your R7000 carefully. See that useless "speech" push-button on the front panel? It and the "Record Speech" control on the rear are going to be co-opted to control the SGC ADSP2's filter functions.

Note: The ADSP2 unit will mount with double-sided tape in the bottom half of the radio, where the IC-EX310 voice synthesizer attaches if it were installed. Reference all wiring runs accordingly.

Start by removing both covers and the rear bulkhead assembly. Remove the switch/connector daughterboard from the rear bulkhead and identify the "Record Speech" switch (second locking push-button down). Locate the black and blue wires which run to solder terminals and eventually the switch in question. Desolder them from the board and then solder them together, covering the connection with a piece of heat shrink tubing. Next, clip the dual microswitch from the small red/yellow/black wires running from the ADSP2 unit; connect the small-gauge yellow wire from the ADSP2 unit to one of the outer terminals of the "Record Speech" switch that you previously isolated. Connect the small-gauge red wire from the ADSP2 to the other outer terminal then connect an 18" piece of similarly sized wire to the center (common) terminal of the "Record Speech" switch. Reinstall daughterboard then bulkhead. Route added wire towards front of radio; you will connect it later.

Remove front panel sub-assembly attaching screws (2 each side) and pull front panel sub-assembly free of main chassis. Locate the SW3 board; remove it (3 screws) and locate the orange and green wires which attach to solder pads on one edge of the board. Desolder them and insulate each with heat-shrink tubing; tuck out of the way. Locate D31 (a diode which attaches to one leg of the "Speech" push-button) and desolder one lead. Next, attach the wire you ran from the rear bulkhead switch to one terminal of the "Speech" switch which you just isolated. Connect the small-gauge black wire from the ADSP2 unit to the other terminal of the "Speech" switch. Examine your work then reinstall SW3 board and front subassembly.

Remove the "Main" board - it has an audio amplifier chip and a couple of relays attached and is on the left side of the radio. Desolder C63, a 0.47uF electrolytic which connects to Pin 1 of the LA2600 audio preamp and serves as an intra-stage coupling capacitor. Run two small shielded audio cables from the IN/OUT ports on the ADSP2 board through the chassis cutout immediately behind the small shielded assembly adjacent to the "Main" board. The sub-miniature shielded cable which connects to the Output" solder pad of the the ADSP2 board goes to the now-vacant hole which connects via board trace to Pin 1 of the LA2600 IC; the other sub-miniature shielded cable (which runs from the "Input" pad of the ADSP2) connects to the other hole where C63 was formerly mounted.

Each shield of the shielded cables gets connected to a convenient grounded foil area on the "Main" board. Leave the far end shields free from anything (and each other).

Power and ground for the SGC board are obtained from IC6, a 7809 regulator - center terminal is ground, and the side which faces away from the reed relay is +9v out. Using this regulator as a power source puts AF preamp, DSP unit and AF PA at the same power/ground reference levels and eliminates ground loops. Dress the power leads for the ADSP2 unit out of the front chassis cutout where the "Main" board mounts then run them to the ADSP2 and solder into place.

Check your work for solder bridges then reinstall the "Main" board and sticky-tape the ADSP2 unit to the R7000's bottom metal bulkhead.

The "Record Speech" button on the back panel now serves to select the DSP mode (NR/notch or audio filter) and the front-panel "Speech" button steps through the filter settings or aggressiveness levels as required by the operator.

All of this is reversible if need be. The rig's appearance is unaltered as well.

My other R7000 will get the conversion over the XMas holidays. If anyone wants to see more info about the process I'll take a bunch of pix and post them as a follow-up to this thread.

NQ6U
12-19-2010, 03:56 PM
Looks interesting, John. My old, pre-DSP Icom rig could use some help with the noisy band conditions here in southern Six-Land so I may look into one of these once I have money to spend on ham radio again.

mw0uzo
12-19-2010, 04:01 PM
Sounds like a nice job :)

Would the switch functions and audio in/out be available via the voice module header?

N8YX
12-19-2010, 04:36 PM
Sounds like a nice job :)

Would the switch functions and audio in/out be available via the voice module header?
Unfortunately, no. That's what prompted the disassembly job. :(

The switch board has a 5V reference applied to a couple of its traces and the Speech switch must be isolated from these, as the ADSP2 unit requires a momentary ground on each of its control lines to properly select the various modes and bandwidths. The IC-EX310 Audio Input line is just that...an "input" to the audio preamp. The main-board audio signal chain must be broken in order to insert the I/O leads. Additionally, the volume-control pot on the front panel merely varies the gain of the AF preamp IC and cannot be used as an injection point.

Was all the effort worth it?

I parked the R7000 on 27.385LSB, activated the NR feature at 13dB level...then activated the audio filter with an "SSB" bandwidth setting. Things are eerily quiet until someone starts talking - and all you hear is their voice. Turn everything back "off" and they are either buried in QRN or their signal is neck-and-neck with it...which makes for very rough copy.

Though my DSP-599zx is a bit more flexible, I think the nod in terms of efficiency - at least in this application - goes to the SGC.

mw0uzo
12-19-2010, 04:51 PM
The switch board has a 5V reference applied to a couple of its traces and the Speech switch must be isolated from these, as the ADSP2 unit requires a momentary ground on each of its control lines to properly select the various modes and bandwidths. The IC-EX310 Audio Input line is just that...an "input" to the audio preamp. The main-board audio signal chain must be broken in order to insert the I/O leads. Additionally, the volume-control pot on the front panel merely varies the gain of the AF preamp IC and cannot be used as an injection point.


Yes - working solutions are quite different to initial ideas, its amazing how many unanticipated hurdles are come across when developing a mod, program or solution to a problem!

I have yet to expeience any good DSP processing. I have probably been exposed to old generation AF dsp only, so it sounds like the later generation dsp is quite good. Must be good for you to consider putting it into your receivers. :)

N8YX
12-21-2010, 11:18 AM
Just finished receiver #2.

This one comes with an Icom RC12 remote.

I figured out a way to use the "Speech" button on the RC12 to strobe the ADSP2's control line, thus giving me the ability to remotely control the filter bandwidths as well. One must use an optoisolator; connect its output switching in parallel with the panel-mounted "Speech" push-button and tie the input to the orange/green lines which were previously removed from the switch.

I have to order a couple of these devices in order to construct the circuit but theoretically it'll work.

WØTKX
12-21-2010, 02:28 PM
Have you ever made a side by side comparison between the SGC and BHI DSP units?

My MFJ-784B unit works OK on SSB, but is much better on digital/CW. On voice modes, it narrows the audio pass band and fidelity even with the NR button off. I only use it for the auto notch on SSB, for multiple carriers. I have listened to the BHI, and have considered getting one... much less of that underwater sound on voice.

N8YX
12-21-2010, 03:03 PM
Have you ever made a side by side comparison between the SGC and BHI DSP units?

My MFJ-784B unit works OK on SSB, but is much better on digital/CW. On voice modes, it narrows the audio pass band and fidelity even with the NR button off. I only use it for the auto notch on SSB, for multiple carriers. I have listened to the BHI, and have considered getting one... much less of that underwater sound on voice.
I just checked the BHI unit out.

Interesting.

Does it have an auto-notch capability? I see "noise reduction" touted quite heavily in their product descriptions but nothing is mentioned about bandwidth variability or notching.

N8YX
12-22-2010, 07:21 AM
The tune job on R7000 #2 just paid off:

I'm listening to 252.150 narrow-band FM at the moment...a few Spanish-speaking bootleggers are chatting on one of our bent-pipe, open transponder MilSats. Antenna is a lowly, preamplified discone. (The roof tower, az-el rotor and UHF-band helix are slated for a 2012 installation so I have to make do with less for a while yet.)

KG4CGC
12-24-2010, 04:21 PM
The tune job on R7000 #2 just paid off:

I'm listening to 252.150 narrow-band FM at the moment...a few Spanish-speaking bootleggers are chatting on one of our bent-pipe, open transponder MilSats. Antenna is a lowly, preamplified discone. (The roof tower, az-el rotor and UHF-band helix are slated for a 2012 installation so I have to make do with less for a while yet.)
Awesomely Cool!