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d104 mic element

A local long time ham/CB friend of mine had 3 old crapped out D-104's with bad elements. I recommended that he try these elements. He did one of them last week. It sounded great, plenty loud with natural sounding voice. He was using an old land Command SSB rig. Others in our local gossip clan, agreed as well.
 
Camaro, you may be on to something with the cord....for an old Tup-9, its been refurbished by the looks of it. Black base looks brand new, cord feels and looks newish. It works but very low modulation unless i talk directly into it, but even that doesnt help much. Obviously the board is working, or it just wouldnt work at all. Hmmmmm, i might take notes where the cord is soldered to the contacts and cut back some and re-solder it. Could someone take close up pix of where the mic wires are on the contacts? Or, could someone tell me the proper wiring of the mic cord to the contacts? Maybe the previous owner has it wired wrong? Meanwhile im gonna put the mic head back to stock, could be something else? Thanx guys
 
also remember the red wire in the head goes to the - side of the element.. I caught myself starting to solder the red wire to the + on the element on one of the ones I did, out of habbit you always think red = positive but not on this one.
 
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Okay, i didnt notice this before, overlooked maybe, lol. The mic cord is pancaked, i mean squished pretty flatish where it goes under the boards screws, im not sure yet if this is the coulprit but sure doesnt look good flat. Im guessing its missing some washers so the cord stays kinda round, lol. Later i will cut back an inch & 1/2, put 2 washers there and hope this thing can come back alive like a D104 should sound. I tried posting a pic, but i took too long earlier, i will try again though. Also when i was testing it earlier i turned the talkback up a bit then turned mic gain up, it sounded very crackly, staticy and not right. It should of squealled like a b*t*ch or when adjust right perfectly quiet. Thanx guys
 
The 1 K resistor establishes the output impedance of the mic element. The amplifier board has an input impedance of 1 million ohms. That's a very significant mismatch and results in lower audio. I'm guessing those who had good results are using a much higher value resistor between 10 k and 33 k ohms. Anything more than this will not provide the element with enough current to function properly. I think I used 22 k in mine and they work great.
 
Okay, i checked out Bulldog's photo's on Facebook of the mic cord wiring to the contact arm's and mine is correct but very schotty soldering. Next is re-doing it my way, then put stock element MC-320 back in. I will then clean the contacts, post back later with my results. I also seen a tip to put a colored felt in the head for a custom look, since ive been putting blue led's in all my equipment i will shop around for bright blue felt.
 
FIXED!!!!!!! Unsoldering the wires on the contacts.......the yellow wire was not only just soldered to the tab, it was sticking in the contacts about a 1/4 inch, almost 1/2 an inch......WHY? We all know the yellow is not used in most (or all) CB's, why did someone have it stuck in the contacts? I also put my stock mic element back in before i tested it, just to start from the beginning. I want to thank all you guys that helped me or even chimed in, im gratefull. Put this one in the fixed column and for future issues, check where the mic cord goes in a D104 any desk mic.....THANX !!!!!
 
I wanted to put the stock one back in before testing it. Since i fixed the short, im done and extremely happy keeping it this way for now. I might try it someday when im done fixing radio stuff, lol. But if its any gauge at all, when it was shorting out with the Radioshacker, it was less audio, thats why i went back to the stock 320 one.
 
i have posted this before, but i like to post this info when i come across a D104 thread in hopes of saving a few of these precious mic elements from the trash can.

if you believe your MC-320 element (or any standard D104 crystal mic element)
has gone bad, DO NOT THROW IT AWAY IR OTHERWISE RUIN IT!!!

there is still a chance that the element is still good, and just needs a little TLC.

see, the big foil surround attaches to the actual crystal element right in the center, and they are connected with a big glob of wax. (usually black)

over years of use, abuse, and mouths full of refuse; this wax will become a bit brittle and work its way loose from the crystal element.

when this happens, the vibration caused by your voice coming into the mic does not get fully transferred to the crystal element, and will cause the mic to sound "tinny", or, "distorted", or have a really low output level.

so how do we bring the mic back to life?
simple.

just use a cigarette lighter, or something similar, and re-melt the wax.

it usually takes a few passes of the lighter over the wax to get it to melt a bit, and of course you dont want to damage the foil or the crystal itself, so dont go crazy.

thats it. if your crystal in the element is still good, then this should bring the mic back to life.

also, dont forget that these mics are very old, and the electrolytics in them dry out with age.
might be a good idea to replace the few that are in there with new ones.

good luck,
LC
 
loosecannon said:
i have posted this before, but i like to post this info when i come across a D104 thread in hopes of saving a few of these precious mic elements from the trash can.

if you believe your MC-320 element (or any standard D104 crystal mic element)
has gone bad, DO NOT THROW IT AWAY IR OTHERWISE RUIN IT!!!

there is still a chance that the element is still good, and just needs a little TLC.

see, the big foil surround attaches to the actual crystal element right in the center, and they are connected with a big glob of wax. (usually black)

over years of use, abuse, and mouths full of refuse; this wax will become a bit brittle and work its way loose from the crystal element.

when this happens, the vibration caused by your voice coming into the mic does not get fully transferred to the crystal element, and will cause the mic to sound "tinny", or, "distorted", or have a really low output level.

so how do we bring the mic back to life?
simple.

just use a cigarette lighter, or something similar, and re-melt the wax.

it usually takes a few passes of the lighter over the wax to get it to melt a bit, and of course you dont want to damage the foil or the crystal itself, so dont go crazy.

thats it. if your crystal in the element is still good, then this should bring the mic back to life.

also, dont forget that these mics are very old, and the electrolytics in them dry out with age.
might be a good idea to replace the few that are in there with new ones.

good luck,
LC
Click to expand...

I need to do that for my K40 speech processor mic. Made the mistake of taking it apart because of intermittent audio. It had not been used for twenty-five years and a couple of smacks mic face down on my leg would usually get it working. My K40 mic aluminum diaphragm has some black goo that I'm guessing where the wax could go.
 
I have to smack my Road devil a couple times too, lol. Maybe i should put this element in that, its only been acting up for 15 yrs or so, lol.
 
Okay, problem is back. I know its not the head anymore, that i know. Its on the PC-100 board, something is failing. When i first key up its fine, peg's all my needles but after around 5-10 seconds the audio falls off the table. Before i throw more money at it and time, what part or parts could be doing this? Disc cap or caps? 2 transisters? A res.? Mic gain trimmer, lol? Something is getting weak during a kinda long QSO.
 

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