[ICOM] Icom Microphones

Wed Aug 3 10:16:12 EDT 2005

Thanks Jim

             Rolly


----- Original Message ----- 
From: "Jim W7RY" <w7ry at centurytel.net>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Sunday, July 31, 2005 8:07 PM
Subject: Re: [ICOM] Icom Microphones


> 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/
>
> ----
> 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/
>