AstAtic D-104 Microphone

© Brooke Clarke 2013
AstAtic D-104 Microphone
Fig 1

Background
Photos as Received
Heil Dynamic Conversion
Related
Links

Background

These have a good reputation and I'm in a microphone mood.  This unit is also called the "chrome lollypop" Planning on making a web page about microphones, but the immediate need is for the ICOM 706 radio.

The T-UG9 stand has a 3 contact socket at the top that holds the microphone and a 3-pole double throw push and hold to talk switch.

There are a number of different microphone elements that might be here, the most common being the MC-321x Crystal element  called the D-104.

In early applications of the mike with tube type transmitters the crystal directly drove the transmitter.  But later radios needed a much lower (the crystal is about 50 k Ohms) impedance so the two transistor amplifier was added in the base to lower the output impedance and slightly shape the audio response.

Photos as Received

There are a couple of problems that are obvious.  The 1/4" stereo phone plug is crushed and the Eveready No. 216 9 volt battery is very dead but it has NOT leaked.

Fig 2
AstAtic D-104
                  Microphone
Fig 3
AstAtic D-104
                  Microphone
What does the R or E switch do? 
Ans from Guy B.
Relay or electronic switching.


Heil Dynamic Conversion

The stock crystal element has a poor reputation for sound quality.  It can be improved using a lot of audio filtering, but a better approach is to replace the element.
Heil Sound makes the HC5.1 retrofit kit for the D-104. May 2013

Heil Sound HC5.1 retrofit kit for the D-104
Heil Sound HC5.1 retrofit kit for the D-104

Heil HC5.1
                  Retro Fit Kit Astatic D D-104 Microphone

Heil HC5.1
                  Retro Fit Kit Astatic D D-104 Microphone



Related



Links

D - 104 Microphone wiring information, mods and circuits.
Add the Astatic D-104 Microphone to the Icom IC-706MKII By W8CWE - uses DC power from 706 to power D-104 amp.
My D-104 Preamplifier - Tone Control By: Alan Wolke, W2AEW (YouTube) - fits in base of D-104 and has Bass & Treble controls
http://www.rbmicro.com/index.php - replacement mike element

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