D-104 history

[kc4yoy]

Does anyone know of a source for Astatic D-104 history?
I'm wondering how to tell what age D-104's are.
I have 3 around here, one has no tag on top of the
D-104 head, one has a stick on label and one has a
riveted on metal tag.
The one with the riveted tag is oldest, I think.
I've had it about 30 years, my wife bought it from a friend to
give to me as a present. There's no telling how long they had
owned it.

73, Ron

[KB2WIG]

http://en.wikipedia.org/wiki/Astatic_Corporation

[Todd, KA1KAQ]

The original models are a bit thicker than the current model, tapped for spring mounting, and sport a large tag with a more fancy script layout. I don't think it's a full inch thick, but maybe. Doesn't have the plug-in base on the head, rather a small sleeve for running the wires out of the bottom. Also has a large screw in the center of the back plate, either for mounting the element inside or as a terminal. Not sure.

The newer, slimmer models (most common) have metal riveted tags on the older models, metallic labels on newer(60s-70s?), and metallic labels with block print on the newest. IIRC, the older ceramic heads had a green metal tag, the standard crystal head tag was black.

You really need one of the originals for your collection, Ron. They're scarce, but not rare. They show up on epay from time to time, usually for $20 or less.

[kc4yoy]

You really need one of the originals for your collection, Ron. They're scarce, but not rare. They show up on epay from time to time, usually for $20 or less.

The complete one that I intend to keep has a green painted metal tag
riveted to the top of the head. It's on a G stand.

I wish there was some information that would indicate when different
versions were made.

Now I just need to find one original screw for the holding the front
and back of the head together. The mic looks great except for the
one odd screw.

73, Ron

[k4kyv]

The original models are a bit thicker than the current model, tapped for spring mounting, and sport a large tag with a more fancy script layout. I don't think it's a full inch thick, but maybe. Doesn't have the plug-in base on the head, rather a small sleeve for running the wires out of the bottom. Also has a large screw in the center of the back plate, either for mounting the element inside or as a terminal. Not sure, never opened up the one I found.

The original first came out in 1933.  According to ads in the old magazines, they changed from the one inch thick head to the more modern 13/16" head in 1937.

Another difference is that the knurling around the edge of the front and back plates of the older thick heads is more detailed.  On the later versions, the knurling is coarser, and seems to be partially filled in with the chrome plating.

The large screw in the middle of the back plate of the earlier ones must have been to hold the early elements in place.  I have opened up several of these mics, and the screw is always simply attached to a nut, and the big screw and nut serve no purpose other than stopping up the hole.  I have a couple of later serial no.'s that have the tapped holes for the spring eyelets, but no big screw in the middle of the back plate.  But all the early ones have a couple of screws on the back plate at the bottom, near the sleeve where the cord comes out.  These hold the clamp that secures the mic cord in place.

I have a very early one with an extra screw in the ring that makes up the side of the mic head, near the sleeve where the cord exits.  I haven't a clue what that one was for.  It too is simply held in place with a nut.

The one I presently use on the air has the thick head, big screw, but no holes for the spring eyelets.  I recall seeing early ads indicating that they were available either spring mounted in a ring or mounted on a desk stand without the ring/springs.

The early ones have a 1/2" sleeve where the cord comes out of the head.  The spring mounted version uses a bakelite or hard rubber grommet that screws into this internal threaded sleeve to protect the cord where it exits the sleeve.

The later models without the big screw in the back have a 3/8" sleeve, still internally threaded.  There is a tapped hole in the rear of the sleeve for a set screw.  This  larger sleeve was designed to accommodate a desk stand adaptor, that snugly slips over the larger diameter sleeve, and the set screw secures it into place.

All the early mics that I have ever opened up had a standard crystal element, mounted in place using foam  rubber pads and glue, just like the most recent models.  I doubt if any of the original 1933 elements survive in working condition.

Click on this link to see a pre-1935 D-104 in action.
http://www.xs4all.nl/~ort0asd/pa0asd.html

Or to just watch the video, here is the link:
http://www.youtube.com/watch?v=qUE04hpwQ1Q&mode=related&search=

Interestingly, you will note that this mic appears to use piece of black cord or elastic to suspend the mic, rather than the usual set of springs.

[W1GFH]

I don't know exactly when Astatic went from riveted to glued on tags, it may have been late 60s.

http://www.jt30.com/jt30page/micdates/micdates.html

[Todd, KA1KAQ]

The large screw in the middle of the back plate of the earlier ones must have been to hold the early elements in place.  I have opened up several of these mics, and the screw is always simply attached to a nut, and the big screw and nut serve no purpose other than stopping up the hole. 

That's probably the case, Don. When I first saw it, the old carbon mic heads came to mind with the center studs used for attaching the mic cable. Made me wonder in that was the original intent for the early D-104, with an insulated wire coming out the bottom and the back stud used for the other. I pulled the front cover off mine and found dried up foam blocks inside used to hold the element in place. Possibly a retrofit from a factory repair?

Maybe someone will turn up an original spec sheet with hook up direction, stating what it was meant for.

[kc4yoy]

http://www.jt30.com/jt30page/micdates/micdates.html

That's an interesting page.
The tag on my D-104 head does not look like
any of those.
It's stamped and the background is filled with green
paint. There is no serial number, where most of these
have the serial number, mine says "CERAMIC".
It has "Conneaut Ohio   made in USA" all one one line
under the Astatic logo.
It looks most like the one from the mid 50's except no serial
number.

Interesting, interesting...

73 all, Ron

[k4kyv]

I purchased a ceramic element to replace the crystal one than went bad on my first D-104 microphone.  But it had lower output and poorer high frequency response than the original crystal one.  Later on, I picked up a couple of good crystal ones, and after many years they still work like new.

Perhaps it would be wise to store an unused D-104 or any other xtal mic in a sealed container with an ample sized bag of silca-gel, to keep the humidity low and moisture out.  It is heat and humidity that kill xtal elements.  I recall taking a defunct one apart once, and the crystal had almost completely disintegrated, and turned into a moist, mud-like grey substance.  Ground up Rochelle salt would probably make better desiccant than Silca-Gel.

[kc4yoy]

Here's photo of the green rivited tag on my D-104.

73, Ron
http://radioheaven.homestead.com/index.html

[kc4yoy]

Gee that was really small.
Let's see if I can make it easier to see.

Ron

[kb2vxa]

Hi guys,

Perhaps you have seen them used as mobile mics in police cars in some old movies. The cord came out the bottom of the neck and the stud fit a hanger on the dashboard. They're seen in plenty of old movies and TV shows, even Captain Midnight used one.