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Old March 15th 06, 01:49 AM posted to rec.radio.amateur.equipment
Phil Kane
 
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Default ICOM IC-229H Schematic

Does anyone have a source for a PDF of the ICOM IC-229H transceiver
schematic? The ICOM site no longer has this on ther site and I
can't find my maintenance manual (if I ever had one).

What I need to know is if there is a bias resistor feeding some
positive voltage to the mike audio pin (pin 1) of the microphone
connector.

WTIA

--
73 de K2ASP - Phil Kane



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Old March 15th 06, 02:02 AM posted to rec.radio.amateur.equipment
Dave Platt
 
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Default ICOM IC-229H Schematic

In article . net,
Phil Kane wrote:

Does anyone have a source for a PDF of the ICOM IC-229H transceiver
schematic? The ICOM site no longer has this on ther site and I
can't find my maintenance manual (if I ever had one).


A quick Google on IC-229 turned up

http://members.tripod.com/~Malzev/cb-funk/ic-229.htm

and there's a PDF scan of the schematic.

What I need to know is if there is a bias resistor feeding some
positive voltage to the mike audio pin (pin 1) of the microphone
connector.


It looks so, based on the schematic cited above. From an 8-volt
supply there is a 100-ohm decoupling resistor, followed by some
electrolytic and other power-supply bypassing to ground. From this
bypassed supply voltage, a 1k resistor R7 is connected to the MIC
line. This same junction then goes through a DC-blocking cap C135 and
thence to the source of a JFET Q2.

So, I think you'll find roughly 8 volts DC sitting on pin 1, when
measured with reference to the microphone ground-return MICE on pin 7.
Short-circuit current to ground would be approx 8 mA.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
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Old March 15th 06, 03:18 AM posted to rec.radio.amateur.equipment
Phil Kane
 
Posts: n/a
Default ICOM IC-229H Schematic

On Wed, 15 Mar 2006 01:02:08 -0000, Dave Platt wrote:

A quick Google on IC-229 turned up

http://members.tripod.com/~Malzev/cb-funk/ic-229.htm

and there's a PDF scan of the schematic.


So, I think you'll find roughly 8 volts DC sitting on pin 1, when
measured with reference to the microphone ground-return MICE on pin 7.
Short-circuit current to ground would be approx 8 mA.


THat's what I needed, Dave. I will be using the IC-229H microhone
with another radio (Elecraft K2) and I needed to make sure that a
bias resistor was needed,

Many thanks.

--
73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon


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Old March 17th 06, 08:11 PM posted to rec.radio.amateur.equipment
Steve Nosko
 
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Default ICOM IC-229H Schematic

Don't forget to check the mods.dk site:
http://www.mods.dk/view.php?ListManuals=icom

73, Steve, K,9.D;C'I


"Dave Platt" wrote in message
...
In article . net,
Phil Kane wrote:

Does anyone have a source for a PDF of the ICOM IC-229H transceiver
schematic? The ICOM site no longer has this on ther site and I
can't find my maintenance manual (if I ever had one).


A quick Google on IC-229 turned up

http://members.tripod.com/~Malzev/cb-funk/ic-229.htm

and there's a PDF scan of the schematic.

What I need to know is if there is a bias resistor feeding some
positive voltage to the mike audio pin (pin 1) of the microphone
connector.


It looks so, based on the schematic cited above. From an 8-volt
supply there is a 100-ohm decoupling resistor, followed by some
electrolytic and other power-supply bypassing to ground. From this
bypassed supply voltage, a 1k resistor R7 is connected to the MIC
line. This same junction then goes through a DC-blocking cap C135 and
thence to the source of a JFET Q2.

So, I think you'll find roughly 8 volts DC sitting on pin 1, when
measured with reference to the microphone ground-return MICE on pin 7.
Short-circuit current to ground would be approx 8 mA.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!





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