Astatic D-104 Microphone: Andre's D104 modded and repairs

Showing posts with label Andre's D104 modded and repairs. Show all posts

ASTATIC SILVER EAGLE'S

Astatic D104 and 10DA mic sound comparison

Astatic D104 and 10DA mic sound comparison

quick listen of the D104 mic and 10DA Super Sidebander hooked up to a mic tester. D104's are tailored for high frequency cutting audio and 10DA is flat and limits all hi frequency after 3khz's.

Astatic Silver Eagle Trouble shooting and repair PART 2

Astatic D-104 Silver Eagle Fet Mod Part 1

D104 Fet modification for better audio on solid state equipment.

Credit: This modification can be found online at Mr. Walter A. Breining is the creator of this information. I do not take credit for his information. But the link above can be downloaded by anyone who wishes to perform the modification. 73's and have fun with this one.

D104 Microphone Source Follower

This video shows how I modified the Astatic D104 microphone and added a JFET source follower circuit to it with a 9V battery. Its a pretty easy mod. I also use a phase switch. I highly recommend using this circuit for the D104. I prefer the source follower rather than a common source type circuit as the D104 mic already has a high audio output and presents a high Z .to the TX speech amp. I have used this circuit in this mic and it has been running for about 5 years with no issues on various transmitters.

How to clean the relay contacts in Astatic D104 with lazy bar stands

Method shown and explained will work with most of the Astatic bases with the lazy bar such as TUP9, Night Eagle, Silver Eagle

#13: D-104 Microphone amplifier / Equalizer for Ham Radio

#13: D-104 Microphone amplifier / Equalizer for Ham Radio

This video describes the microphone preamp and equalizer that I designed in 1999 to use with my Astatic D-104 microphone with my ham radio. The D-104 suffers from two issues when used with modern ham radios - impedance mismatch and non-ideal frequency response. The circuit addresses both of these issues. The video briefly describes the circuit, it's frequency response, and demonstrates the bass and treble adjustments using an oscilloscope and signal generator.

More information can be found on this webpage:
http://www.qsl.net/w2aew/myd104amp.html

Note that it is quite likely that you will have to employ strategically placed bypass capacitors, ferrite beads, etc. to keep RF from coupling into this circuit. Every application and installation is different, so you may have to "play" with these components to eliminate RF from your circuit. You can see some of the ferrite beads I used when the video shows the circuit board in the base of the microphone.

Demonstration of the the Vintage Astatic D-104 Microphone

Demonstration of the the Vintage Astatic D-104 Microphone

3 different mikes, although you may think not!

Wade's D104 hiFi mod

Here we take a standard D104 non amp and make it into a economy HiFi amped mic. Enjoy Stickman

Edward's D104 converted

Edward's D104 converted

We convert Edward's D104 to an amplified mic so it could work with his Icom radio. Enjoy Stickman

VA3AGV.com - ANDRE - Amateur Radio - Canada

Figure 1 In the original circuit, the first stage of the D-104 amplifier provides the load for the mike element. Originally it uses a common NPN bi-polar transistor.

The microphone element is connected through a .01uf capacitor to the base of the first transistor. A 1 Meg resistor is connected from 9v to the base to bias the transistor for linear operation.

The transistor emitter is grounded through a 150-k ohm resistor. A 0.1 uf capacitor also connects to the emitter. This couples the audio output into the next stage providing for DC inter-stage voltage isolation. This is a very common emitter follower configuration.

A 450 pf. (00047) uf capacitor is connected from the emitter to the base. The purpose of this “boot-strapping” capacitor is to create positive feedback from the emitter to the base. This artificially raises the base impedance of this input.

The collector connects to board foil that supplies 9v.

There is a second stage that feeds the mike cord. This is not needed with the FET modification as the FET amplifier provides plenty of output for most applications. I have found that the sound is better without this second stage so it is eliminated in the modification.