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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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18th Sep 2021, 2:02 am | #1 |
Heptode
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 593
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What type of microphone is this ?
It came today with a very old Airmed (before Clement Clarke) Airlite 70 headset. I'm familiar with the newer half-oval shaped microphones that clip on to the boom but I've not seen a round one before. There are no obvious part numbers or type descriptions on the unit. Thankyou.
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18th Sep 2021, 9:15 am | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,803
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Re: What type of microphone is this ?
Some aircraft radios/intercoms used carbon microphones, some used moving coil. So headsets have long been modular with interchangeable microphone capsules. So you could have either Dynamic ones usually have their magnets screened, so waving one around near the panel doesn't upset the compass so you can't tell that way. Try it on a dynamic mike input on something and if you don't get a response, it's probably carbon.
David
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18th Sep 2021, 11:20 am | #3 |
Heptode
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 593
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Re: What type of microphone is this ?
Thanks David. The size of it suggests it's either carbon or moving coil with a built-in matching amplifier to boost its output. I will test it eventually but I thought someone might have an idea in the meantime.
Interestingly, it came fitted with a PO610 connector, i.e. two x BPO phone patch plugs mounted side by side in a single casing. These used to be used in American ATC comms panels but I don't know of any particular use in the UK. |
18th Sep 2021, 9:42 pm | #4 |
Heptode
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 593
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Re: What type of microphone is this ?
I've tried it on a plain audio amplifier (no dc voltage bias) and got nothing. Tried it with 7.2v going through - it works. So either carbon or amplified dynamic or amplified electret.
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18th Sep 2021, 11:36 pm | #5 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,803
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Re: What type of microphone is this ?
If it's noisy, then it's carbon
Otherwise, anybody's guess. DAvid
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
19th Sep 2021, 9:30 am | #6 |
Heptode
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 593
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Re: What type of microphone is this ?
Not overly noisy. I've just noticed it only has holes on one side so it's not likely to be a cardioid type either.
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19th Sep 2021, 10:59 am | #7 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,803
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Re: What type of microphone is this ?
Most aviation headset microphones have holes both sides and may even contain two elements for ambient noise cancellation. It might be for ground use (tower or radar op) or be for something with a quiet cockpit (jet, glider)
Glider pilots like using no headset, a speaker and then have the mike on a gooseneck boom. The makers of these use dynamic capsules. We did our radio transceiver for electrets as used in most David Clark headsets, so gliders were a problem and needed an inline amplifier. David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
19th Sep 2021, 11:22 am | #8 |
Heptode
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 593
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Re: What type of microphone is this ?
I might email Clement Clarke on the offchance someone there can identify it. It's about fifty years old so I'm not hopeful.
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