[ICOM] Icom Microphones

[Jim W7RY]

Rolly.

Use a computer headset. They are available at any computer store I.e. 
Office Depot, or equivalent.


Icom provides a small DC bias voltage at the microphone pins so you just 
have to hook it up and go.  Don't use a blocking capacitor. You need the DC 
bias to run the electrictit element in the headset microphone.

  The earphone just plugs into the headphone jack on the 756.

I've used them with great success!


Good luck!
73
Jim W7RY





At 06:09 PM 7/31/2005, you wrote:
>Does anyone know about portable phone (not cell phones) headsets. How 
>might they be connected to Icom's (in my case a 756 orig).
>
>Rolly  W7DGX
>
>
>----- Original Message ----- From: "Adam Farson" <farson at shaw.ca>
>To: "'ICOM Reflector'" <icom at mailman.qth.net>
>Sent: Sunday, July 31, 2005 12:51 PM
>Subject: RE: [ICOM] Icom Microphones
>
>
>>Hi Bob,
>>
>>You may be able to adapt the headset microphones to your IC-728 if they meet
>>these conditions:
>>
>>Source impedance 200 to 600 ohms
>>
>>Output voltage 2 to 3 mV on voice peaks
>>
>>You can get an approximate idea of the source impedance by looking at the
>>circuitry that the mic drives (if possible). Typically, an external mic for
>>a cellphone will be low-impedance (600 ohms or less). You can check the
>>output with an oscilloscope, if you have access to one.
>>
>>A telephone headset mic has a very high output voltage, of the order of 500
>>mV to 1V on voice peaks. It has to be compatible with a carbon mic in a
>>telephone set. You will need to build an attenuator to reduce the output to
>>3 mV or less.
>>
>>A 0.47 to 1 uF non-polarised capacitor must be connected between the mic or
>>attenuator output and the mic input of the radio (Pin 1), to prevent
>>shorting the electret polarising voltage.
>>
>>Incidentally, any of the Icom mics with the 8-pin Foster plug except some of
>>the very early ones will fit any Icom transceiver fitted with the standard
>>8-pin Foster socket. This includes the SM-6, SM-8, SM-10, SM-20, HM-12,
>>HM-14 and HM-36. There are also modular/Foster adapters (both genders).
>>
>>Here is the mic socket pinout:
>>
>>http://www.qsl.net/ab4oj/icom/heilsound/icom_mic.html
>>
>>
>>You may be able to power the external mic amplifier (as needed) from the
>>radio's +8V supply (Pin 2. Caution! 10mA max.) The Plantronics has an
>>amplifier, and may require a higher voltage than 8V. I am not sure whether
>>the cellphone headsets require external power or not. If the headset element
>>is an electret, you will be able to power it from Pin 2 via a 4.7K or 10K
>>ohm resistor between Pin 2 and the output lead (with the capacitor between
>>the output lead and Pin 2), or by connecting its output to Pin 2 without the
>>capacitor.
>>
>>Hope this helps. If you would like some diagrams, I can send them to you
>>off-list.
>>
>>Cheers for now, 73,
>>Adam VA7OJ/AB4OJ
>>
>>-----Original Message-----
>>From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
>>Behalf Of KE5CTY Bob
>>Sent: 31 July 2005 12:29
>>To: Icom Reflector
>>Subject: [ICOM] Icom Microphones
>>
>>In talking to others, I understand that Icom Microphones are special
>>creatures for the Icom line of radios.
>>
>>Sometimes I have noticed - you can't even swap them between Icom Models
>>themselves.
>>
>>So I am asking this question to avoid messing something up on my rig.
>>
>>I have an IC-728 and a hand microphone, I would like to be able to build a
>>headset microphone for it for higher quality audio output.
>>
>>I have some old Plantronics amplified headsets that were made for using on a
>>regular telephone and some headsets from old cell phones.
>>
>>One from the cell phones (a Belkin) I especially like because of the quality
>>of the earpiece.
>>
>>I am already using it plugged into the Headphone jack in the front of the
>>rig for listening.
>>
>>Since I have Audio Output at the microphone jack I would like to be able to
>>wire this headset into the mic input for both functions of Mic and Headset.
>>What considerations do I need to look at to make this possible?
>>
>>I don't have the money to buy a Heil or anything like that - so please let's
>>stay off that subject as it is frustrating for me already.
>>
>>73 fer nw,
>>Bob
>>KE5CTY
>>
>>
>>Scanned by WinProxy
>>http://www.Ositis.com/
>>----
>>Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
>>Icom Users Net: Sundays, 1700Z, 14.316 MHz
>>Icom FAQ: http://www.qsl.net/icom/
>
>----
>Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
>Icom Users Net: Sundays, 1700Z, 14.316 MHz
>Icom FAQ: http://www.qsl.net/icom/