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Old 25-03-2015, 20:39   #1
Jd1
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Icom M802 voice compression mod

I have searched and searched for information on the modification needed to allow front panel activation of the built in speech compression system. Alas, I have been unable to find this information.
Some dealers (Dockside comes to mind) will do this mod at a reasonable cost when you buy a new M802 from them but this leaves a lot of people who are not able to activate speech compression.
I have found speculation on the internet that it only involves installing a resistor ..... but nobody seems to know exactly which resistor needs to be installed.
Does anyone have more details on this mod ?
Does anyone have an Icom M-802 HF radio that was modified to allow access to the 'comp' menu screen? The quickest way to find out what is involved in this mod seems to be to take a picture of a specific area on one of the boards in the M802 and compare that to an unmodified unit.
Just imagine the karma points you could earn by posting a picture of the modified circuit board !
Anybody with a modified M802 willing to snap a picture for us ?
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Old 25-03-2015, 22:19   #2
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Re: Icom M802 voice compression mod

Did you try a google search? Searching on "icom m802 voice compression" seemed to do the trick.

Icom M-802 Programming Instructions
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Old 25-03-2015, 22:29   #3
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Re: Icom M802 voice compression mod

No, that didn't do the trick. If you look at the instructions about turning speech compression on/off and look at the very bottom of that box, you will see a note that says "* A Hardware modification is required to access Mode B menu selections."
It is that hardware modification that I would like details for if anyone can help out.
Thanks for looking though !
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Old 26-03-2015, 08:41   #4
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Re: Icom M802 voice compression mod

I don't know about other people but I can't read the yellow, even though it is large font. Must have some color deficit I guess as I've noticed it before. Ah, just realized its yellow on white background I can't read. Yellow on black works.

Sorry that didn't work for you. There are a few SSB gurus on here that may respond. btrayfors for one.
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Old 26-03-2015, 08:50   #5
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Re: Icom M802 voice compression mod

Sorry about that .... I copy/pasted it from the web page
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Old 26-03-2015, 08:55   #6
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Re: Icom M802 voice compression mod

Quote:
Originally Posted by DeepFrz View Post
I don't know about other people but I can't read the yellow, even though it is large font. Must have some color deficit I guess as I've noticed it before. Ah, just realized its yellow on white background I can't read. Yellow on black works..
Highlight it with your mouse and you can read it.

"* A Hardware modification is required to access Mode B menu selections."
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Old 31-03-2015, 17:47   #7
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Re: Icom M802 voice compression mod

Jd1,
My original M-802 was delivered in 2004 with the speech compressor On, and I turned On the speech compressor on my second M-802 via software (CS-802)...

So, I cannot help with your query, except to offer the advice to NOT worry about having a front panel capability to turn it On and Off...as you will NOT need to turn it Off...and this is not just some cruiser BS, but I have actual data...
Or send your radio to Gary at Dockside, and have a pro do it...the tiny surface-mount devices in these modern radios are NOT conducive to amateur techs / novice solder'ers....

Quote:
Originally Posted by Jd1 View Post
I have searched and searched for information on the modification needed to allow front panel activation of the built in speech compression system. Alas, I have been unable to find this information.
Some dealers (Dockside comes to mind) will do this mod at a reasonable cost when you buy a new M802 from them but this leaves a lot of people who are not able to activate speech compression.
Now, if you desire the nitty-gritty details, this has all been discussed before....
IC-M802 Compression

Bottom line:
The M-802's "speech compression" is done digitally inside the DSP modulator, and as such is very clean, and does NOT introduce distortions / artifacts, nor does it contribute to IMD, nor adversely affect transmit bandwidth nor spectral purity...
(technically, according to lab tests, the radio misses the spectral purity spec by about 1.5db at 150 watts out with the speech compressor On....but does pass at 100 watts with it On, or at 150 watts with if Off....but even missing the spec by 1.5db, still places it 20db+ better than ham rigs or older/out-of-alignment maritime rigs that you hear on the air....so no worries here...)

Please understand that this was designed into the radio to be used primarily On....as the peak-to-average voice ratio programming of the DSP modulator is designed for this "speech compressor" to be On, which is certainly noticeable by the rather poor "peak-to-average" voice (poor "talk power") when the speech compressor is Off...

Further understand that this is NOT what modern ham rigs use (many using crappy ALC-based, distortion-inducing, "ALC-based speech processors", and others use distortion-inducing audio-based speech processors, etc...), but the M-802's DSP-based speech compressor actually improves audio quality as well as peak-to-average ratio....

The M-802's DSP speech compressor has no effect on PACTOR modem use, assuming you set the modem drive levels correctly....

If we were talking about a ham rig / a rig with an adjustable mic gain control, or a radio connected to an ext. 1500 watt amplifier and multiple directional antennas, etc. then I would certainly agree the ability to easily/quickly turn off the speech compressor, would be a necessity.....but that is not the case here...

The only caveat here would be if you use the radio near a noisy environment, such as near a running engine, etc....and with the "speech compressor" On, there can be some background noise pick-up that can be disturbing to some others listening to you (poor operating practice!)....
So, if this is the case in your situation, then I understand the desire to be able to turn it off...




BTW, there are some videos and threads that will help you understand the M-802, HF-DSC communications, long range Marine HF comms in general, and offshore weather access, etc...
Have a look...
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr

https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y

https://www.youtube.com/playlist?lis...zdjTJjHlChruyY


Marine SSB Stuff (how-to better use / proeprly-install SSB, & troubleshoot RFI, etc.)

Icom M-802 Instr Videos(basic-adv) & LIVE DSC-Distress Call

New HF-DSC Explanation and LIVE Demonstration Videos

Offshore / Hi-Seas Weather data / forecasts



I hope this helps...

Fair winds...

John
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Old 31-03-2015, 20:21   #8
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Re: Icom M802 voice compression mod

Thanks John !
I was aware of the 'nitty gritty' thread but it was good of you to post the link and possibly help other people to get some background info. I will eventually get the cloning software so I can turn the compression on but I would think that when I have my engine running the environment will be too noisy. On the other hand, I have no idea if I would ever be playing with the HF radio while motoring.
Soldering surface mount devices is not that difficult if (IF) one has the right equipment. I agree that it is easy to make a dog's breakfast out of it though.
I am also most curious what other things can be enabled via hardware mods .... I had secretly hoped that maybe somebody might have been curious enough to look a the other resistor positions (or better yet, look at the software)
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Old 31-03-2015, 22:16   #9
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Re: Icom M802 voice compression mod

Speech compression in the M802 can be turned on via the correct version of Icom's software (intended for dealers only). No hardware modification is necessary, unless you need the ability to turn speech comp. off and on at will. As John said, this is unlikely to be needed; leave the compression on all the time.

I understand that Icom in WA will not do this for you, but many dealers and electronic technicians who have the software will.

There are several versions of the necessary software. The correct version is chosen by the serial number of your radio (which appears on the main 802 unit, not the control head).

It only takes a few minutes and is done by attaching a cloning cable from a laptop to the headphone jack on the front of the 802's control head.

Other mods can be done at the same time, e.g., entering into memory a new set of pre-programmed frequencies, entering or changing the MMSI number, etc.

You need to find someone with the right software who's willing to do the mod(s) for you.

IMHO, all 802's should have this mod done; it really makes a difference.

Bill
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