Question: New rig-old mic?

[ki4kgw]

A local ham has a couple of Atastatic d104 preamplified desk mic he wants to unload.  I'de like to get a desk mic for my Icom 706MKIIG and since an sm-8 isnt exactly what a 15 year old calls cheap  , I was wondering how that mic would work with that rig.  I've got a feeling that it wont work good because the radio really isnt made for an amplified mic and the MKIIG only emloys 600 ohm microphone impedence.  So i guess my biggest question is can i use a mic with an impendence other than 600 ohms or will this harm my radio?  Please explain how this works.  Also, how will a pre-amp mic work with my radio?  Will it cause distortion?  Should i just try it and see if i can turn the preamp and the mic gain down far enough that it sounds good?  I've always used the stock mic so i have a lot of question.  Maybe i should just forget the whole idea, but i really like the anteque look of these mics.

Also if i do decide to give it a whirl, how do i connect the mic connector (i dont know if its 8 pin or 4 pin; the guy selling it is blind and I'm afraid to ask) to the 8 pin modular on my radio.

Thanx for answereing my questions and bearing with a new ham who still has a lot to learn.

                                                               73, KI4KGW

[w3jn]

I don't see any reason the D-ten-four wouldn't work with your Icom.  The fact that it has a preamp is a good thing, the preamp is much lower output impedance than the standalone D-104 crystal cartidge.  A standalone D-104 definitely would NOT be a good match for the Icom.

Just turn the gain way down on the D-104 preamp.  You'll have to experiment a bit to get the level right.

As far as the mic plug goes, is that a standard RJ-11 connector?  You should be able to rig up a short pigtail adapter cable.  I don't know the pinout of the Icom mike plug, that should be in the manual somewhere.

73 John

[W1RKW]

Jesse,
Many times I've heard many new hams complain that they are ignored or made fun of or a bunch of other things and made to feel unwelcome to amateur radio.  The one thing this forum does not do is just that.  There are a great bunch of guys on this board.  I'm a veteran newbie to AM.  Everyone has welcomed me and have been helpful above and beyond the call.  So I don't think you have anything to worry about when it comes to question asking.  Ask away.  That is the only way to learn.  And there's no such thing as a dumb question.

I too see no reason why the D104 would not work either.  The only issue I see is the physical connection.  The connector your Icom uses, you may need to reconfigure the wiring of the D104 to suit the rig.  And you may need to find a suitable connector to fit the rig connector.  Other than that you shouldn't have any problem.  And yes, if you tinker with the preamp level settings it should do the job.

[Herb K2VH]

KI4KGW said:

"I'de like to get a desk mic for my Icom 706MKIIG and since an sm-8 isnt exactly what a 15 year old calls cheap." 

Wow, Jesse, that brings back memories.  I was 15 when I first got my ticket way back in 1954, and had to save up from my paper route, and birthday and Christmas money to buy radio stuff.  I believe I did talk my uncle into getting me a new microphone for my birthday.

I think it's just great that you've got your General, and getting on phone, and also on this bulletin board.  You should have no trouble at all with that D-104, if you follow what the guys above have told you.  With the build-in preamp it should match your rig just fine.  All you got to do is figure out where to get the right plug to plug it in with (Ye gawds!!!--I just ended a sentence with two prepositions!!!)

Ask lots of questions, as that's the way you will learn.  And call in on the air too.  If we can hear you, we'll be glad to work you.

73, and enjoy your new hobby.  It's a great one!

Herb, K2VH
Penn Yan, New York (also known as PY,NY)

[KB2WIG]

Jesse,
           If you need the manual for the 706' its on the ICOM web site. I have  the MK2 and manual. I  don't know how different the MK2 and MK2G are, so I dont want to give you bad info. My sugestion is to get /find a 8 contact "patch" cable and cut it in half. This will save you time and trouble as you connect things......  In my manual  there is the schematic dia for the HM-103 mic..... looks like a nice & easy & cheap project. I guess it might be in the MK2G manual also.....good luck and keep us informed as to how it goes....  klc

[Vortex Joe - N3IBX]

Jesse,
       Welcome aboard! You've come to the right place for advice for getting on the radio; especially on AM. To tell you the truth, I've never heard a D-Ten-Four hooked up a an Icom 706, but why not? The only problem I can think of is an impeadance mismatch between the mike and your radio. I think the Icom 706 wants to see a low impeadance (200-600 ohm) at the audio input, and depending on which D104 version you have (ceramic,crystal element) you may have to use a step down transformer in order to get the proper impeadance match between your radio and microphonium.

Best Regards and hope to hear you on the air sometime in the near future. With low power (20-25 W output) your best bet would be to get on the AM window on 40 Meters (7285KC-7295KC) and get a few audio checks from others.
                                   Joe Cro N3IBX

[Herb K2VH]

Jesse,
        The only problem I can think of is an impeadance mismatch between the mike and your radio. I think the Icom 706 wants to see a low impeadance (200-600 ohm) at the audio input, and depending on which D104 version you have (ceramic,crystal element) you may have to use a step down transformer in order to get the proper impeadance match between your radio and microphonium. 

Hey Joe,

The preamp in the D-104 base will take care of the mismatch.

Vell Hung (VH in Chinese)

[Vortex Joe - N3IBX]

Jesse,
        The only problem I can think of is an impeadance mismatch between the mike and your radio. I think the Icom 706 wants to see a low impeadance (200-600 ohm) at the audio input, and depending on which D104 version you have (ceramic,crystal element) you may have to use a step down transformer in order to get the proper impeadance match between your radio and microphonium. 

Hey Joe,

The preamp in the D-104 base will take care of the mismatch.

Vell Hung (VH in Chinese)

Herb- Definitely FB! I'd hook it up as is and see what comes out the other end.
Regards,
           Joe N3IBX

[Herb K2VH]

Joe N3IBX wrote:
"I'd hook it up as is and see what comes out the other end."

That's a good philosophy to have, Joe, especially when eating N2YR's hot peppers 
Hung

[Vortex Joe - N3IBX]

Joe N3IBX wrote:
"I'd hook it up as is and see what comes out the other end."

That's a good philosophy to have, Joe, especially when eating N2YR's hot peppers 
Hung

Herb - Joe's hot peppers are good for the soul!

[W1ATR]

Hi all. I've been down this road a LOT with Icom rigs in the past, and due to the fact that I'm a chrome lollipop crackhead, (currently have 6 or 7 d104se's on different rigs), I've learned they can be made to work on anything, but there are a few things that MUST be considered when trying to jack one up to an Icom.

The low down:

On the mkIIg, when looking at the jack on the radio, tab on bottom,(front or rear jack, doesn't matter), the rj-45 is 8 pins, and numbered from left to right. The pinout follows below:

Pin

1. +8VDC
2. Freq up/down
3. AF out
4. PTT (Push to talk)
5. Mic Lo (This is the mic element ground)
6. Mic Hi (Mic audio IN) (8VDC phantom voltage also on this pin)
7. Gnd (Chassis ground)
8. Squelch switch


Now the wiring for a d104 would be Red on pin 4, Shield braid on pin 5, White on pin 6, and Blue on pin 7. This can be done with adapter cables, or whatever as long as the wiring is followed through, or the best way would be to put the rj-45 right on the d104 cable end. (This is also the quickest, and cleanest way to do it.)

The down side is you'll need a telemaster tool to do it, about 25 bucks in the phone/video junk section at home cheapo, and the rj-45's are there too. Those are cheap in box quantities.

Just strip the mic cable 1/2" from a cleanly cutoff end, cut off the wires that aren't needed, (black, yellow), and don't strip the individual wires left over. Twist the shield braid so it's nice and stiff, line all of them up from left to right (Red, Shield, White, Blue), and push them into the correct slots in the connector, (4567), while holding the wires in the connecter securely, insert into the tool, and squeeze.

Sounds like a lot to do, but after some practice on old phone cords, it only takes about 30 seconds to stake on one of these connectors to a mic cord.


Now we have to pay attention here, this is specific just to Icom rigs. (If this step is ignored, the crazy phools at Icom ask 300 bucks to fix it with a 15 cent resistor) Pin 6 has a voltage coming out of the radio that is called "phantom power",(this has nothing to do with the "Phantom of the opera" either), this will show 8VDC when read with a multi-meter. This voltage is there to provide power for "Electret" mic elements only, and NEEDS to be removed when trying to hook up other mics, Dynamic, ceramic, etc.. With a d104, this DC voltage is separated from the AC audio signal by using a cap inside the mic on the white wire. This is done by lifting the white wire from the board on the d104 and soldering one leg of a .047mF mylar capacitor to the point where the white wire was removed, then solder the white wire to the other leg of the cap. Insulate this point so nothing shorts out, and put the bottom back on the mic, your done. (While some mic preamps provide enough resistance not to overload this phantom power, most won't, and there's a current limiting resister on the audio board in the radio that will let go to protect the radio's voltage regulator. Ask me how I know this, and I'll tell you about this puff of smoke I once knew.)

The Result: It'll work, it'll sound OK, but not great. Using a d104 on the newer icom's works out well due to the fact that newer icom mic preamps are already 20dB down in gain from most radio's, and a d104 is one hot tamale. You have to get someone on the air with patience to help you tune that puppy up, but a good starting point on a mkIIg is 3-4 on the mic gain, and just cracked open on the d104. Be ready for plenty of the "Your tinney" reports until you get it adjusted right. (This is from the impedance mis-match. Even an amplified d104 is still double+ what the radio's mic input impedance is.)

The light at the end of the tunnel.

There's a MUCH faster, MUCH better sounding, MUCH easier way to do this whole microphonium hookin' up thang and here you go:

I've done this on multiple Icom rigs I have here, (mkIIg, 756, etc...), and the end result is effen beautiful audio that sounds wide, boomy, and processed, without all the extra eq's, and assorted junque in line. This mic will sound great on AM, FM, and SSB. Not to mention, super simple to hook up.

This will ONLY work with an amplified mic that has a buttload of gain, like the immortal, Godsent, d104. (Or, naturally, external audio gear)

On the back of that mkIIg, you'll see the 13pin DIN jack, now hopefully, when you got the radio, you got the splitter cable that plugs into that jack, and breaks out to 2 connectors, an 8 pin DIN (Acc#1), and a 7pin DIN (Acc#2)

Get an 8 pin DIN connector, and wire the d104 to it as follows. Pin 2=sheild and blue together, pin 3=red, and pin 4=white. Plug it into the 8 pin jack provided by the adapter cable, and plug it all into the back of the radio. That's it, your done.

Now pin 3 is the hsend (HF), so there's a menu setting to adjust so it will key up on all bands. (I almost forgot about this one, hihi) Turn the radio off, then hold the lock button, and turn the power back on. Scroll to menu # 30 (VSEND SEL), and turn the VFO knob until "OFF" is indicated. turn the radio off, then back on to get back to normal operation. All this setting does is make it so that the hsend connection controls keyup for all bands (HF/VHF/UHF)..

Settings: None of the internal audio circuitry is used anymore, as this setup puts the audio right into the high impedance balanced modulator input which is a way,WAY better impedance match for a hi-Z mic like a d104. The Balanced Modulator won't choke down any part of that d104 and any audio frequencies that come out of the mic, will go out on the air damn near transparently.

Setup the radio: Turn the mic gain on the radio all the way down, it no longer controls the output audio level. Leave the compressor OFF, you sure as hell ain't gonna need it, and it no longer works anyway. All other circuits still work like normal, like the ALC.

Turn the d104 down all the way CCW, and turn it up just 1/4 of a turn, (this is the only mic gain that controls your audio, so keep a phillips screwdriver handy) and get on the air with someone you normally talk to on a quiet frequency, and adjust the level up or down from there. Only make small adjustments at a time because these mics will REALLY crank the audio out on the air. Turned all the way, your likely to vaporize someones' speaker on the other end, no to mention over-modulate like a mofo.

AM/FM settings will be about the same(1/4 turn-ish), and SSB settings will always be higher (around 3/4 turn-ish), but you'll get the hang of it on where the mic needs to be set depending on transmit mode.(the reason for keeping a screwdriver handy) On one of my mics, I put a small 3 way switch on the back side of the base, and wired in 3 different pots, then set each one individually for AM-FM-SSB. Now depending on mode, I just have to flip the switch to the right position for the amount of drive from the mic for that mode.

The mkIIg on AM with this setup will sound pretty damn good, but like with any mic setup, turn the carrier power down to around 10-15 watts.

Be ready to deal with the piss and moaners if you clunk down that iron hammer on 2 meters FM.

Enjoy, and welcome aboard.
Jared W1ATR