[Elecraft] Knowles HC-3 Mic Element Replacement For Heil HC-5

[Fred Jensen]

Tony,

Every single "military microphone" I've ever encountered [a lot] 
required very close talking to get any output.  They're often used in 
extreme noise environments and that's one simple way of removing the 
ambient noise such as on an aircraft.  They are often used right up next 
to your mouth, and would be "breathy" except they had limited high freq 
response.  Designed for a very specific purpose.  Don't know how any 
would sound in ham service with a pre-amp, but Jim, K9YC, is on this 
list, he retired from a career as an audio professional and so far, he's 
my go-to-guy.  Maybe he'll read this and offer his take.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

Tony wrote on 3/20/2022 4:25 PM:
> All:
>
> I finally got the chance to test the Knowles HC-3 military microphone 
> element I ordered. The eBay seller claimed that it had the same 
> frequency response as the vintage Heil HC-5 and it is very close in 
> that respect. However, it's not nearly as sensitive as the Heil HC-5 
> so it requires A LOT more mic gain.
>
> It also needs to be close-talked to the point where you're lips touch 
> the element screen. Move 1/2 inch away from the mic and the audio 
> drops off to nothing. The Heil HC-5/4 I have were also made to be 
> close-talked, but they have enough sensitivity so you can be 2 or 3 
> inches from the element and still maintain good output.
>
> I asked Bob Heil about all this and he said Knowles built the HC-3 for 
> him which eventually morphed into the original HC-4 and HC-5. He also 
> mentioned that a pre-amp could be used with the HC-3 to make it work.
>
>
> So the $40 dollar military surplus HC-3 has the same high articulation 
> as the HC-5, but it lacks sensitive. I should also mention that the 
> HC-3 is larger by a 1/4 inch give or take so it's not a drop in 
> replacement for Heil headsets like the BM-10.
>
>
> Tony -K2MO



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