D 104 microphone elements

David Harmon dwharmon at IX.NETCOM.COM
Mon Jan 8 00:31:03 EST 2001

Hi John...in addition to what Lee said, my experience is that the D-104
mikes are the best sounding mikes for AM as well as SSB.
There are two type cartridges available...ceramic and crystal.
Crystal is the one you want.
The later, amplified version like you apparently have is described below
from another email from a local guy some time back......follow their
By the way, I have 3 of them and they are all the older type from swap meets
or part of whole station buys. All without amplifiers/impedance matching
such as yours. All have the original crystal cartridges and just sound
With the Collins stuff I have, I get unsolicited compliments on the audio.
I believe CTI Audio either is the distributor or took over Astatic.
The Crystal elements are available from HRO for about $18.
        Best Regards
                Dave K6XYZ


Hi Collins Collectors et al:

I asked CTI Audio about the differences of their two cartridges for the
D-104 Astatic Mike; i.e. One is Crystal and one is Ceramic.  Everyone,
seems to highly reccommend this mike with COLLINS equipment.  CTI Audio
has very good technical support; they immediately answer questions;
unlike some other companies.  I also previously asked them how to rewire
a "Silver Eagle"; D-104 to work with the Collins equipment (thus
eliminating their internal 9v battery preamplifier).  Their response was
very interesting; as they were more concerned with impedance matching
then the supposed increase in audio gain which was only a by-product.  I
post this information also because a few months ago a lot of
information was discussed on Collins Microphones; the D-104 etc.

> To Technical Information:
> I have a D-104 Silver eagle microphe; and wish to use it with my collins
Radio Equipment...I know I need just the White wire which is the center or
hot; and the red which is the PTT.  Also I know the Blue and Ground wires
should be connected together.

MY QUESTION is:  I want to use the mike without the built in pre-amp;
How do I jumper or remove x,y,z, wires inside the base unit; so that i
can still have the total use of the mike switches; but totally bypass
the preamp and battery requirement???  Mike has a yellow wire and a Grey
wire coming from the mast to the pre-amp board.  The other color wires
coming off the Preamp board and going to the PTT switch terminal strip
are  1. A white wire  2. a Violet wire  3.a brown/yellow wire 4. a black
Would you please let me know how to accomplish this???

Thank you,

Jerry Solomon K6HMI


Hello Jerry
There's no easy or sure way to do what you want to do. The best thing
we've been able to come up with is to take the yellow wire coming from
the head of the mic and connect it directly to the white wire going to
the radio. Disconnect both wires from anything but themselves. This
should make the audio work without the amplifier but realizing that it
is on all the time. Also realize that the amplifier was not put there to
amplify, the amplification is just a side effect. The amplifier was put
there to match impedance's, because the impedance of that mic head is
500,000 ohms which doesn't work with most radios. The switching circuits
should still work. Good luck
Frank Walford
Senior Technician

Second Answer on Choice of Cartridges.
CTI Audio Technical Support wrote:

Hello Jerry
There are two main differences between ceramic and crystal cartridges.
Ceramic cartridges are more durable but the tone is less bity, more
mellow. Crystal cartridges are less durable but have a hotter more bity
tone.  If theres anything else you need let me know.
> Frank Walford
> Senior Technician

Jerry K6HMI  Other comments!

I am not so sure that Collins Equipment really wants to see a mike
entering the equipment at around 500,000 ohms impedance.  Obviously, the
preamp is concerned with matching Hi impedance mikes to the input; for
stability and to reduce hum..I think...they must have thought a lot
about this before putting this preamp in the "Silver Eagle" units; I am
not technical enough to know their engineering.  Any comments


Jerry K6HMI

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