The AM Forum

Hey Crew, I've been working on improving a 706MkIIG for AM operation for the past few weeks. I've put together a page about the details of the mods I've done, it's near finished. I've been fixing the mistakes as I find them. Take a peek at my progress to date, if you find wording, mistakes or things that just don't make sense; by all means point the issues out.

Thanks

http://users.wpi.edu/~smithw/706_Mods/index.html

If you'd like to take a look at the nice clean install that's possible with this little mobile you can surf on over to my current mobile page.

http://users.wpi.edu/~smithw/new_mobile/new_mobile.html

catch you on the air!

Bill,
Nice job as usual...tnx for posting the results.

Guys I added a section about using the internal Speech Processor to taper the audio if needed.

Curious if you looked into going directly into the modulator input through Pin 11 of the ACC jack. I don't have the schematic in front of me but I thought it bypass's all the audio restricting circuitry. Decent quality hand mike, single transistor mike amp, and pin also available to key the rig on ACC. Going this way probably disables the processor but that's a small drawback.

Sorry Pete, I wish that was true. That audio input is a 100mV RMS input that parallels the output of the mic pre-amp stage... It still drives the Pre-emphasis, L.P.F and Limiter before hitting the modulator.

Not to be confused with the 1V 9600BAUD input which is available only to drive the reactance modulator directly.

I suppose with some rework it could be made to drive the modulator directly, which I'm not interested in. I want to retain the mic jack on the head unit functionality and the availablity to control the gain of the mic pre-amp from the menu. Plus as I added on the other day, to switch in the processor to cut the lows and mids back out if needed.

MMMM-K?

Too bad. I guess they learned to do it better with the 746 PRO, 756 PRO series, and the 7800. Input jack ACC1, pin #(?) goes directly into the modulation stage. That's where my audio input goes to from the microphone/hardware. Front panel mike gain and processor controls are disabled. Much better audio response than going through the front mike jack. Maybe the new replacement, IC-7000 (rumor) will offer improvements in this area.
(http://www.rigpix.com/icom/ic7000.jpg)

That IC-7000 looks pretty cool Pete!

Wonder where they got the inspiration for that front panel design?

(http://www.sachsreport.com/tokyo%20at%20night.jpg)

Bill,
     Many thanks for the information. To my knowledge, you're the first to come up with audio mods for the IC-706. Many people have them and like me, have been looking to improve their audio on AM.

You deserve more than a "attboy" for your work. It appears you've done quite a bit of research and experimentation, and put in a lot of time in the project, before you came up with the finished product.

Hehe, talk about going off the road trying to work the rig!

Actually, I'm kinda psyched, 706's will be dirt cheap when they come out with that thing.

Hey Crew, I made some changes to the 706 mods page, flipped around a capacitor and moved a resistor, no biggie.

Guys I updated the mods page for the 706MkII, The service manual was correct about D683, I was wrong. It really doesn't matter as I explained in the mods page because you'll be removing this diode anyway.

I'm supprized that nobody pointed this out.

I need your help crew finding these simple mistakes; Yes, Obsessive Compulsive personalities are welcome to point things out!