A question about the ubiquitous D-104

[N2IDU]

I have  a D104 cartridge that has very low output and horrid audio suitable for sideband only. Having nothing to lose, I carefully removed the diaphragm to discover that the crystal element had come undone from the thin metal support which attaches directly to two of the corners of the crystal and than to the metal diaphragm.This device would transmit the sound vibrations directly to the crystal. This tiny support looks like a minature coat hanger. My question is what type of glue/varnish,lacquer,shellac, sealing wax was used. Whatever the substance is, it is dark amber in color and very brittle. This coating covers the actual crystal element itself as well as fastens the support hanger to the corners of the element. In any event, I don't want to start expirementing with thinners, reducers and solvents which might permanently ruin the element. If any of you D104 aficionados knows the answer, please 'edumakate' me. Thanks,
Peter
Old Shincracker, Vt.

[KX5JT]

I don't have your answer but I did find this link that seems to be like an encyclopedia on the D-104....

http://www.qsl.net/wa2mzf/d104.html

[W2VW]

Let me know if you ever figure it out. I have several dozen dead D-104s here which were drowned.

[WBear2GCR]

To heck with that problem - I say anything will work that sticks and is hard.
Epoxy, thickened cyanoacrylate ("crazy glue") or similar... I guess.

I have a nice one where one of the foil connection to the xtal came off!!
Right at the square xtal.
How to fix that??
How did they make the connection in the first place??

Darned if I can see how they made the connections!
Looks to me like the xtal is wrapped in foil???
Now, how does that work??

Btw, I'm guessing it's maybe shellac or rosin... both of those are alcohol solvable, so ought to be easy enough to test without destruction. Might be varnish, but somehow I don't think so.

                     _-_-bear

Dave, if I had 10, I'd experiment. I have one dead one that I opened up. I had a digital photo at one time of the guts... and the broken foil lead

[W1GFH]

Looks like a couple brushstrokes of model cement hold it together.

[ka3zlr]

Howdy,

 There's always the quick fix, acquire a Bob Heil HC-5 element an place close to the middle
or if ya wana get real fancy pull the guts out of the head an line with a good quality felt an
place in center with a Popsicle stick round the ends just to size then cayno thick each end
an spray with accelerant making sure the stick is centered in the ring both work I've done
that fix for quite a few friends.

Otherwise:

I lay the pieces where they go one at a time and use good Cyano Thick just a touch then
shoot with the accelerant spray.

my 2cts

73

Jack.

Which ever you choose make sure you have good Clean metal to metal contact then cement.

[KL7OF]

Fingernail polish...the cheap kind that smells like laquer....Has held on for 10 years for the exactsame repair on D-104 here....gud luk   

[KX5JT]

Heil also makes a D-104 "replacement" http://www.heilsound.com/amateur/products/hc104/index.htm

But heck!  I got an old beatup D-104 for 12 bucks on eBay.  It was an original type, without any ptt on the base OR on the stem and no "preamp" in the base.  The element IS perfect.  The chrome was pitted bad and the base has some beginning corrosion.  Some diet Pepsi took all the pits and rust off the chrome (it works WONDERS, it's mostly phosphoric acid, and get diet so you don't have the sugars).  Just apply liberally with a sham and rub and rub.... then Mother's mag and chrome polish...

Sanded down the base, used some aluminum filler (jb weld like stuff) and sanded that down... primed then shot with hammertone grey and clear coat.... that 12 dollar D-104 is better than new looking!  Sounds GREAT too, but alas, unless I need that punchy D-104 audio, I stick to my Marshall and Behringer stuff.

My point is you can find old D-104's pretty cheap and they usually have a good crystal element.  A friend of mine picked up one at an old used record shop for 5 bucks and gave it to me for Christmas a couple years ago.  It was in bad shape cosmetically but it worked great.  I shipped that off to Geo and he says it works great!

Howdy,

 There's always the quick fix, acquire a Bob Heil HC-5 element an place close to the middle
or if ya wana get real fancy pull the guts out of the head an line with a good quality felt an
place in center with a Popsicle stick round the ends just to size then cayno thick each end
an spray with accelerant making sure the stick is centered in the ring both work I've done
that fix for quite a few friends.

Otherwise:

I lay the pieces where they go one at a time and use good Cyano Thick just a touch then
shoot with the accelerant spray.

my 2cts

73

Jack.

Which ever you choose make sure you have good Clean metal to metal contact then cement.

[KX5JT]

Fingernail polish...the cheap kind that smells like laquer....Has held on for 10 years for the exactsame repair on D-104 here....gud luk   

And I thought I read somewhere that it was just simple wax... *shrug*

[N3DRB The Derb]

ya want the ones that are on G stands, or sometimes you run across one that has the regular plain old adapter to a screw on mike boom stand.

just get the one never used for CB use. the elements in them are good most of the time.

[k4kyv]

Another CB trick is to poke the metal diaphragm full of holes so it looks like a salt shaker.  Never could figure out what that was supposed to accomplish.  I have one like that and it sounds about as good as a tin-can telephone, real metallic and restricted.

I have another one that has very low output.  I suspect the xtal is bad, resulting from too much heat and/or humidity.  If I can figure out how to remove the diaphragm without damage, I plan to try swapping out diaphragms and see how well the one with the good crystal works.

[WBear2GCR]

Don, removing the diaphragm is pretty simple.

The stuff on the tip of the diaphragm is connected to the yoke (shown in the earlier jpeg) with a wax. Basically that's "sealing wax" as was once used on letters. It melts fairly low in temp and gets pretty hard when cool.

So you take a razor knife and gently slide around the perimeter to lift the edges of the diaphragm from the bakelite separating the glue bond. when the edges are free you take a reasonably hot iron and get it close to the wax... it will melt, carefully lift the diaphragm away from the body and off the yoke. I'd have the body held so that stuff is not moving and shifting during this last part... comes right off...

                         _-_-bear

[ka3zlr]

Heil also makes a D-104 "replacement" http://www.heilsound.com/amateur/products/hc104/index.htm

But heck!  I got an old beatup D-104 for 12 bucks on eBay.  It was an original type, without any ptt on the base OR on the stem and no "preamp" in the base.  The element IS perfect.  The chrome was pitted bad and the base has some beginning corrosion.  Some diet Pepsi took all the pits and rust off the chrome (it works WONDERS, it's mostly phosphoric acid, and get diet so you don't have the sugars).  Just apply liberally with a sham and rub and rub.... then Mother's mag and chrome polish...

Sanded down the base, used some aluminum filler (jb weld like stuff) and sanded that down... primed then shot with hammertone grey and clear coat.... that 12 dollar D-104 is better than new looking!  Sounds GREAT too, but alas, unless I need that punchy D-104 audio, I stick to my Marshall and Behringer stuff.

My point is you can find old D-104's pretty cheap and they usually have a good crystal element.  A friend of mine picked up one at an old used record shop for 5 bucks and gave it to me for Christmas a couple years ago.  It was in bad shape cosmetically but it worked great.  I shipped that off to Geo and he says it works great!

Howdy,

 There's always the quick fix, acquire a Bob Heil HC-5 element an place close to the middle
or if ya wana get real fancy pull the guts out of the head an line with a good quality felt an
place in center with a Popsicle stick round the ends just to size then cayno thick each end
an spray with accelerant making sure the stick is centered in the ring both work I've done
that fix for quite a few friends.

Otherwise:

I lay the pieces where they go one at a time and use good Cyano Thick just a touch then
shoot with the accelerant spray.

my 2cts

73

Jack.

Which ever you choose make sure you have good Clean metal to metal contact then cement.

That website talks about Ikems and the like for electret elements phantom power he don't need
all that.


73

Jack.

[KX5JT]

Jack, the top part was talking about Icoms and the need for phantom voltage, but the rest of the page is not about Icoms....  you mentioned the HC-5 and if you read passed the Icom section you see it's using an hc-5 with some mounting stuff to fit it into the d-104 head.  I only linked it as to show that Heil actually sells that as a kit for the d-104.  I personally wouldn't put that element into the head of a d-104, I'd just find a beater somewhere with a good crystal element.  As the topic inferred, the D-104 is ubiquitous!  

Anyway even all these suggestions is beyond his original question of what is the substance holding the crystal to the diaphragm.  Some sore of sealing resin/wax apparently.

73 John KX5JT

[ka3zlr]

That's all fine but I like an HC-5 in there it really broadens the response run them both
together in that head wether it's a G stand or not you might like the output. We do have
a License to experiment don't we screw the Factories We Build here.....

The transformer is cool keep RF problems down, but heck most of these parts can be had
anywhere why give Heil more money he makes enough now with this audio craz thing going
on the bands "Oh I must have a Goooooldline"....LOL....Oh yes my Goldline and my 10 Pc
Audio Rack does quite well doesn't it...lololol I'm so Broadcast.

Spend Mo Money Dalla Bill.


73

Jack.

[k4kyv]

Heil also makes a D-104 "replacement" http://www.heilsound.com/amateur/products/hc104/index.htm

I don't think Bob's replacement element is supposed to have as good a low frequency response as the original un-amplified D-104 crystal mic has, if the input stage of the transmitter presents a load of 5 megohms or higher. It was primarily designed with SSB use in mind.

But Bob is spot-on regarding the 2kHz peak.

[ka3zlr]

I'll stick with the HC-5 replacement a little carpet work in the head an move on.


73

Jack.

[k4kyv]

I have been experimenting with the balanced output D-104, driving a pushpull pre-amp. No rf pickup and minimal hum, even with a.c. on the tube filaments.  Before, I had to run DC on the input stage filament to get rid of the hum.

No RF suppression between mic and tube grids.  The old single-ended pre-amp required R-C suppression to keep RF out, especially on 40m. The mic element feeds directly into the push pull grids, using the two grid leak resistors to establish the the balanced 180° audio to the grids. No other components in the  circuit, other than shielded leads to each grid.  Each tube has a 10 megohm grid resistor, so the total resistive load on the mic is 20 megohms.

[w1vtp]

Howdy,

 There's always the quick fix, acquire a Bob Heil HC-5 element an place close to the middle
or if ya wana get real fancy pull the guts out of the head an line with a good quality felt an
place in center with a Popsicle stick round the ends just to size then cayno thick each end
an spray with accelerant making sure the stick is centered in the ring both work I've done
that fix for quite a few friends.

Otherwise:

I lay the pieces where they go one at a time and use good Cyano Thick just a touch then
shoot with the accelerant spray.

my 2cts

73

Jack.

Which ever you choose make sure you have good Clean metal to metal contact then cement.

Jack

I'd be interested in some more info on this process you just mentioned

Al