Unexpected Interesting Reward!

[sunbulls]

If you're into total restoration, I would also think about making that Demco look as good as it sounds. I would either completely resurface the metal front plate with a wire brush. (the brushed aluminum look), or personalize it with a custom call letter plate to coverup the scratches / worn out logo . The same type of plastic plate used on military uniforms or those commonly sold at a ham fests. Trophy shops will custom engrave some great looking metal plates too. Just a thought....

 

[Dmans]

I find your last sentence confusing.

AtLarge,
The 980SSB has a 6 pin mike jack on the radio but a four wire mike cable.

Sunbulls,
I still haven't opened the Shure/Demco yet. Way too many other projects going on. The back burner is getting overloaded!

73's
David

 

[Dmans]

I finally came back to this project and discovered the mike element in the Shure/Demco 444T is alive and well.
The fault was in the wiring. I did not take a picture of the underside before removing the mike cord, but above is a picture of the end that was connected inside the base of the mike. The shorter pieces of wire were soldered to the leaf switches and were twisted to the coiled cord. After removing this disaster, I put a new non coiled mike cable on it, cleaned it up, replaced the worn out 9v battery connector and tested it. Wow!! Too much gain for my liking but it is alive!
The battery clip or holder is missing from the bottom and the battery “compartment” (a plastic-like box) needs to be replaced and I can officially pronounce this project done and remove it from the back burner. Below are a few more “after” pictures.


I have “transformed” an old Turner 251 (I think) similar to Shadetree’s Dukane into a decent desk mike. More on that later. Got to build a 9v battery box!
73
David

 

[Mudfoot]

I just got an old Dukane mic. I am going to see if I can fit two AA batteries in the base.
View attachment 30451

Nice

 

[WINKDOGG]

I just got an old Dukane mic. I am going to see if I can fit two AA batteries in the base.
View attachment 30451

Man I hate to piggy back a thread but I love that MIC!!

I did check out that element and for the price I am def going to order a few to play with ! I too have a couple Shure mics from estate sales and swap meets most are just hand held vocal style more modern "sugar cones" but I have a desk model from an old factory PA system as well as a desktop from a roller skating rink DJ stand ! Both are XLR wired I believe need to dig them out !

Sorry again Dmans I like your stuff 100% But Shadetree Mechanic really got me with his mic lol , great thread and interesting element !

73's Talk to you guys in DX Land 4-2-ZERO King of the mud ducks in the north east !!

 

[Dmans]

So as the title of this thread goes, I was handed another “orphaned” microphone as “payment” for repairing a Turner +2 and a new headset/microphone combo from a friend of mine.
I had previously gotten my hands on some Adafruit electret modules for experimenting and figured this latest “orphan” would be a good candidate for a transplant.
As I opened up the bottom side of this, what I believe to be a Turner 251, paging microphone I discovered I was not the first to open it up. (No surprise there!) All of the wiring on the leaf switch contacts was previously cobbled together much like the Shure 444T. Since I don’t like coiled microphone cords, I first replaced the cord and connector and discovered no output from the element.
I believe the element is crystal or ceramic but haven’t found any numbers on the mike or element to determine the true part or model number of this microphone. Hence my assumption it may be a Turner 251. Could be a 254 or ???
I am a fan of these and felt like it should be kept as original looking as possible. The Old School charm of this microphone is appealing to me and using a straight Mike cord only adds to that appeal. So with these thoughts in mind, I did not want to alter the exterior to add a battery to power the Adafruit element but I have other options. After being involved in a couple of Blues Bands for the last 20 years or so, I have hoarded some equipment/gear and have some stage microphones that were collecting dust. One such mike, an Electro Voice N/D 257B had an element in it that is close in size physically to my latest orphan and the voice frequency response is certainly wide enough for my communications needs.



So after removing the element from the EV I was able to nest it in the head of the orphan and close up the mike so the from all appearances it looked stock. Testing the EV element in the Turner Orphan was met with great reports on audio quality both on my Kenwood and 139 XLR.
So it looks like this Turner has a new home and should be see a few more years of use.

Electro Voice element fitted into the head stock of the Orphan.



Nice outside appearance after getting some much needed cleaning.




I like breathing new life into “orphaned” gear even if retrofitting it with some new technology. I still have a handful of Adafruit elements/modules I will be saving for other projects.

73
David

 

[Woody-202]

So as the title of this thread goes, I was handed another “orphaned” microphone as “payment” for repairing a Turner +2 and a new headset/microphone combo from a friend of mine.
I had previously gotten my hands on some Adafruit electret modules for experimenting and figured this latest “orphan” would be a good candidate for a transplant.
As I opened up the bottom side of this, what I believe to be a Turner 251, paging microphone I discovered I was not the first to open it up. (No surprise there!) All of the wiring on the leaf switch contacts was previously cobbled together much like the Shure 444T. Since I don’t like coiled microphone cords, I first replaced the cord and connector and discovered no output from the element.
I believe the element is crystal or ceramic but haven’t found any numbers on the mike or element to determine the true part or model number of this microphone. Hence my assumption it may be a Turner 251. Could be a 254 or ???
I am a fan of these and felt like it should be kept as original looking as possible. The Old School charm of this microphone is appealing to me and using a straight Mike cord only adds to that appeal. So with these thoughts in mind, I did not want to alter the exterior to add a battery to power the Adafruit element but I have other options. After being involved in a couple of Blues Bands for the last 20 years or so, I have hoarded some equipment/gear and have some stage microphones that were collecting dust. One such mike, an Electro Voice N/D 257B had an element in it that is close in size physically to my latest orphan and the voice frequency response is certainly wide enough for my communications needs. View attachment 32558

View attachment 32559

So after removing the element from the EV I was able to nest it in the head of the orphan and close up the mike so the from all appearances it looked stock. Testing the EV element in the Turner Orphan was met with great reports on audio quality both on my Kenwood and 139 XLR.
So it looks like this Turner has a new home and should be see a few more years of use.

Electro Voice element fitted into the head stock of the Orphan.
View attachment 32560
View attachment 32561

Nice outside appearance after getting some much needed cleaning.
View attachment 32562
View attachment 32563
View attachment 32564

I like breathing new life into “orphaned” gear even if retrofitting it with some new technology. I still have a handful of Adafruit elements/modules I will be saving for other projects.

73
David

I like the brushed chrome on the 251. I don't recall owning one though. I used to use the 254 on a Tram and got vg audio reports too.

 

[Dmans]

Today I was able to fabricate a battery box and holder for the Shure/Demco 444T. First a picture of what was left of the original holder.


This was attached to the bottom cover by 2 “riv-nuts” and 1 brass rivet. The riv-nuts” were also used to secure the bottom battery clip to the microphone bottom. I’m not sure what the material used for this box is but I did find what I think is a suitable replacement.

I’m sure I am not the only one that despises the hard clear plastic packaging used on many products today. You know the stuff that is razor blade sharp and almost requires a hack saw to open. I found a piece that was large enough from a container of concrete anchor bolts to form a battery “tray” from a single piece of "razor blade plastic". Careful measurements of what was left of the original and a pattern drawn out on graph paper allowed me to trace it out on the “razor blade plastic”. After bending the sides (with some heat from my hot air solder station) I was able to form a suitable replacement.


I cut out around the “riv-nuts” so that I could add the holder and pop riveted the new box to the bottom cover.
All that was left was a holder or clip on the bottom. This was made with a scrap of sheet metal and a piece of foam glued to the metal strip.


I’m happy to remove this from the back burner but don’t think I will use it. I’m not a fan of amplified microphones and this one has way more gain than most I have run across in almost 50 years in this hobby. It will look good on a shelf though!!

Get out there and restore, repair or build something!!

73
David

 

[Shadetree Mechanic]

I have an old Minute Man 1 that needed a lot of help. It looked like it had gotten wet at one point. I used a 1/2 AA lithium that is 3v and used a 10k pot to trim the audio. Then I experimented with the coupling capacitor for the audio. Ended up natural sounding at 0.1mfd without being muddy. This thing sounds amazing and gives my rack gear a run for it's money. Thanks for sharing the details of this little jem!

 

[Dmans]

Shadetree,
It is a pretty clever circuit! And sounds GREAT!
I have been (slowly) transforming the Astatic/Drake to use on my TR-296 (aka "The Turd") but the 296 has an audio problem internal to the chassis. If I can stay on that project for more than 5 minutes, I should be able to get it straightened out and dial in the Astatic/Drake for use on it. Then it will get transplanted into the old Realistic TRC-49 chassis.
That module really got my 980SSB to working like it should.

Maybe you could try one in your Dukane? Got any radios with DC voltage available at the mike jack?

73
David

 

[Shadetree Mechanic]

I am definitely going to get a few more of these. The 1/2AA lithium would fit well in the Dukane. I was hesitant to replace the Dukane element if it still works, but now I am convinced that this little module would be way better. I have a 980 and an Anytone 5555 so they would be good candidates for a retro fit in the stock mic. I might install one inside my 29 as a direct inject in place of the audio transformer. So many possibilities, and they can be had for about $2 each if you are willing to wait for them to come from China.

 

[Dmans]

I wasn't aware they could be had from China. I am in no hurry and stay backed up with other projects all the time. There may be a dozen or so more modules in my future!

73
David

 

[Shadetree Mechanic]

Update on the china made modules and a bump for anyone who hasn't seen this little gem yet. I ordered 4 of the China ones and got them a while back. This was before the Wuhan Flu was on our radar. (Honestly I expected it to be like SARS) Well anyway I finally got around to putting one of these in the Duane MIC and they work as advertised.I run this on my Galaxy 99 on the back workbench. I got tired of having to grab the Minuteman hand mic every time I wanted to talk while working on stuff. The AGC function works great and I can modulate cleanly from two feet away, or pick it up two handed for a bolder sound while maintaining the same audio level. I will make a build thread of it soon.

 

[Dmans]

Shadetree,
Glad to hear of your success! I was successful with "repacking" the 980SSB stock mike and a Turner Plus 3.
I have tried to modify the Astatic 987L that was gifted to me for use on my TR-296 (aka "The Turd") but have been unsuccessful. (Had to add a battery to this one) It will work the PA function but not transmit audio-either AM or SSB. I think the 5 pin plug and the switching arrangement in the 987L are not playing well together or......I know you need to add a capacitor on the unit but can't remember if it is series with the audio line or across the positive supply to audio line. Can you help me on that detail? What value and location of the capacitor?
Doesn't seem as though I will ever have time to finish any of my own projects. (139XLR-bad final and/or power supply transistor, another 148GTL recap,138XLR recap, Sears Road Talker only 10 or 12 of 40 channels working .......)

73
David

 

[Shadetree Mechanic]

Yeah, whenever I sit down at my workbench, my mind goes in ten directions with what I am going to work on in the next ten minuets. Haha! But to answer your question, the capacitor goes in series on the audio out from the module. This is needed to decouple the DC voltage. I think its like 1.5v DC that the audio rides on coming out. The Dukane mic I used two tantalum capacitors back to back (negative to negative) to make a non polarized cap. The value was 100uF each which would make 50uF total in series. This will pass all the bass and will be too muddy on a radio that has been widened (modified for increased audio response) but sounds great on a stock rig. The Minuet Man I had two 0.22uF electrolytics back to back for 0.1uF total and it sounded great, but I since have changed to the 50uF tantalum set when I changed the configuration to work with the Cobra style "ground pin 4 for audio" setup. The way I do the module is to switch the positive power with one set of contacts and do the audio and pin 4 stuff with the other set. The whole mic element mute and negative switching will give you a dead battery as there is a small leakage current out of the audio out if you leave the positive connected all the time. The mic element mute contacts will cause a squeal with the Cobra pin 4 audio setup. I hope I explained that in a way that is understandable. I can see it clearly in my head. I can make a diagram if anyone needs it.
Chris