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Author Topic: ASTATIC D-104 ( D in this case means dead)  (Read 5701 times)
W7GIF
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Posts: 126




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« on: August 19, 2012, 08:22:19 PM »

Sadly, when I pulled a couple of pristine D-104's from the (dry) storage cabinet, I discovered that both were dead......absolutely no output. My aged mind recalls something from long ago about the "free" crystals of the original D-104's doing something like "clumping"....rendering them "dead", with little or no output. Has my recollection failed me, or is this a trait of the old D-104s? If it is a trait, is there any solution to bring them back to life other than replacing the cartridge/element?

Thanks......
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K2OWK
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« Reply #1 on: August 19, 2012, 09:20:46 PM »

I have a question. Is the D-104 the one with the amplified base? If not how were the mikes stored (high humidity air conditioning)? If they are the crystal elements that are bad, best thing is to replace them. Elements for the D-104 are relatively easily available at a low price. Last how did you check the mikes?
I have two D-104s with amplified bases. They work perfectly. I just need to replace the 9 volt battery about every 6 months or so. I use mine with a Yaesu FT-450AT and have received reports of excellent audio (even on FM). Both of mine have the original elements.

73s

K2OWK
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AA4PB
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« Reply #2 on: August 20, 2012, 05:02:11 AM »

You might be thinking about the old carbon elements that we used to tap i the hand in order to break up the carbon clumps. The original D104 had a crystal element that was rather sensitive to heat and cold changes that could crack the element. The only solution for a cracked element is to replace it.
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W7GIF
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« Reply #3 on: August 20, 2012, 07:40:30 AM »

I'll bet you're right about my recollection of "clumping" pertaining to the carbon mics. The D-104's are  unamplified on the "G" stands, and have been stored in low humidity air conditioning. The mics were checked on the stands with two transmitters first, then the heads were checked with a 1KhZ impedance meter off the stands. The wiring checks OK.
Thankfully, my Shure 444D and 505C and EV664 dynamic mics are working just fine. I'll open the D-104 heads today, and see if there's anything obvious that would have caused them to go dormant. Given that they've been stored in a dry, a/c environment, and never subjected to mechanical shock I was surprised to discover them INOP.

Actually, although not the best for DX'ing audio "punch", the EV664 does a very nice job of faithfully reproducing voice for rag-chewing and laid-back QSO's.
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G3RZP
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« Reply #4 on: August 20, 2012, 08:14:19 AM »

The usual problem with crystal microphones is the absorption of humidity by the Rochelle salt crystal. Even in a relatively well controlled atmosphere it happens eventually: sometimes a gentle baking in the oven at about 40 to 50 degrees Centigrade would restore them.
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W8JI
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« Reply #5 on: August 20, 2012, 12:44:01 PM »

I've heard others complain about D104's, but every one I've had has worked a long time. I still have one from 1970 or so that is working fine.
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N4NYY
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« Reply #6 on: August 20, 2012, 02:54:05 PM »

I've heard others complain about D104's, but every one I've had has worked a long time. I still have one from 1970 or so that is working fine.

You want the one I painted emerald green? LOL.
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KE3WD
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« Reply #7 on: August 20, 2012, 03:44:11 PM »

Before tossing the cartridge, check to see if the mic audio passes thru the PTT leaf switches, after long storage the contacts can become corroded and high resistance. 

Wet piece of printer paper or calling card with a wee bit of Deoxit, pass between each of the contacts several times, try mic again. 


73
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W7GIF
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« Reply #8 on: August 20, 2012, 05:59:33 PM »

Interesting development.Disassembled the heads of both failed D-104's, and found no obvious problems. Both measured "open" at the cartridge terminals with a 1KHz impedance meter, and both are ink-stamped "ASTATIC MC-320" with date codes of '78 and '80. My third D-104 which functions perfectly, has "pat. pending" paper labels on the back of the element, with no element p/n or date code. It's 1 KHz impedance measures at about 150K ohms. This has to be a much earlier D-104, with the nameplate riveted to the top of the mic head, rather than glued on like the later mics. Interesting that the older cartridge is still alive, when all three have been stored in the identical environment for the same length of time.

I'll try the gentle "baking" of the failed cartridges at 100F to 120F suggested by G3RZP. Nothing to lose there.
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N4NYY
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« Reply #9 on: August 20, 2012, 06:15:12 PM »

There you to be a Heil HC-104 dynamic element for the D-104, and heard it sounded great. But they stopped selling it for some reason.
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W9GB
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Posts: 2623




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« Reply #10 on: August 21, 2012, 05:56:35 AM »

The Astatic D-104 microphone element is crystal, Hi-Z.

Potassium sodium tartrate (Rochelle) crystals
http://en.wikipedia.org/wiki/Potassium_sodium_tartrate

Testing Rochelle salt crystals
http://rimstar.org/materials/piezo/rochelle1.htm

Make your own replacements
http://www.mo-seph.com/node/489

Kobitone (Japan) is no longer manufacturing these elements, as of Janaury 2012.
This was the common source, via Mouser, for Astatic D-104 owners.

The growing of rochelle salt crystals for radio experiments
Charles W. Clifford
Journal of Chemical Education, 1939, 16 (2), p 86
DOI: 10.1021/ed016p86
Publication Date: February 1939
http://pubs.acs.org/doi/abs/10.1021/ed016p86
« Last Edit: August 21, 2012, 06:01:17 AM by W9GB » Logged
W7GIF
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Posts: 126




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« Reply #11 on: August 21, 2012, 08:21:24 AM »

The Astatic D-104 microphone element is crystal, Hi-Z.

Potassium sodium tartrate (Rochelle) crystals
http://en.wikipedia.org/wiki/Potassium_sodium_tartrate

Testing Rochelle salt crystals
http://rimstar.org/materials/piezo/rochelle1.htm

Make your own replacements
http://www.mo-seph.com/node/489

Kobitone (Japan) is no longer manufacturing these elements, as of Janaury 2012.
This was the common source, via Mouser, for Astatic D-104 owners.

The growing of rochelle salt crystals for radio experiments
Charles W. Clifford
Journal of Chemical Education, 1939, 16 (2), p 86
DOI: 10.1021/ed016p86
Publication Date: February 1939
http://pubs.acs.org/doi/abs/10.1021/ed016p86
Thanks! That is really informative. I wonder if the original "pat. pending" elements like the one (of three) of mine which is still live (and that doesn't carry the MC-320 marking) is a domestic (pre-Kobitone) mfg element/cartridge. The data just from my small (statistically invalid) sample of three units suggests that perhaps a difference in materials or processes used for the mfg of the MC-320 cartridges may have contributed to a shorter cartridge life......or a cartridge less resistant to deterioration/degradation resulting from "normal" environmental conditions.
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W9GB
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Posts: 2623




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« Reply #12 on: August 21, 2012, 12:09:43 PM »

Quote
I wonder if the original "pat. pending" elements like the one (of three) of mine which is still live
(and that doesn't carry the MC-320 marking) is a domestic (pre-Kobitone) mfg element/cartridge.
Now you are jabbering .....

1. Astatic made there own crystal elements, since early 1930s when the D-104 was first introduced.  They may have outsourced later or near end of mfg.
Rochelle crystals have distinct DISADVANTAGES .. failures (crystal structure fractures) under Humidity, Moisture, G-Shock/Dropping, Heat, etc.

The Potassium sodium tartrate (Rochelle) crystals are hygroscopic ... they absorb water .. this property is referred to as: deliquescence
http://en.wikipedia.org/wiki/Hygroscopy#Deliquescence

2. READ the matertials and Internet links that I provided ... tells the whole story.

3. At the beginning of the 20th Century -- 2 microphone elements were widely used
Crystal - (Piezo-electric effect) and Carbon - (Alexander G. Bell, teklephone systems).

4. AFTER WW2, Japanese manufacturing was rebuilt and in 1960s some of the first Japanese mfg. crystal elements were exported to USA.
These were widely sold with tape recorders, Lafayette, Allied and Radio Shack stores in 1960s and early 1970s.
Mouser was importing these crystal elements from Kobitone.
I understand that Ceramic (Hi-Z) microphone elements are still available.

5. VERY FEW Crystal Mic Element mfg. have survived today.  
Dynamic and Elecret (requiring DC bias), which have 150 to 1,000 ohms (Z) outputs,
 are the 2 most popular and used microphone elements today.
« Last Edit: August 21, 2012, 12:18:58 PM by W9GB » Logged
AA4PB
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Posts: 12854




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« Reply #13 on: August 21, 2012, 12:39:36 PM »

You also used to be able to get the D104 with a ceramic element that offered the same impedance and output level but was more rugged.
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KE3WD
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Posts: 5689




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« Reply #14 on: August 21, 2012, 02:07:18 PM »

There was also a dynamic head for the TUG base at one time.  Bullet shaped, I once bought a TenTec Omni C from estate sale which had one on it, no preamp in base, audio reports were great. 

But I bought the rig for its CW capabilities, really.  And that was awesome. 

73
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