[ARC5] Carbon mic pops

[WA5CAB at cs.com]

I agree.  This is unusual for such circuits in general.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 11/29/2016 10:40:06 AM Central Standard Time, 
arc5 at mailman.qth.net writes: 
> All of those carbon mike circuits were very similar in design back then. 
> I have never encountered one that "popped" as you describe.
>  This makes me wonder if there was some unknown mod done to the mike or 
> the preamp circuit. I've seen some sites where they replace the carbon 
> element with electret
> mike elements. I don't know how well that works- maybe its fine, but I 
> always used carbon types with no problems.
> 
> 
> Try engaging the PTT without the mike in circuit to see if you still get 
> the noise. it could be from some other source further down the chain...
> 
> On Monday, November 28, 2016 10:17 PM, "hwhall at compuserve.com" <
> hwhall at compuserve.com> wrote:
> 
> All the caps were replaced before we powered up. The "battery" DC power 
> supply is quiet, no hum with the PTT held down. Just a loud pop when the PTT 
> contacts close. 
> 
> Wayne
> 
> -----Original Message-----
> From: J Mcvey <ac2eu at yahoo.com>
> To: hwhall <hwhall at compuserve.com>; arc5 <arc5 at mailman.qth.net>; 
> milsurplus <milsurplus at mailman.qth.net>
> Sent: Mon, Nov 28, 2016 8:03 pm
> Subject: Re: [ARC5] Carbon mic pops
> 
> My guess is that you have an open cap in the Mic DC filter circuit. 
> 
> On Monday, November 28, 2016 9:53 PM, "hwhall at compuserve.com" <
> hwhall at compuserve.com> wrote:
> 
> I have a question about use of carbon mics in circuits like interphones. 
> Mics like the T-17 leave the mic "battery" current circuit open until the 
> PTT is pressed to speak. But the contact closure creates a huge pop in the 
> headphones attached to the amp output. Does anyone know how this was dealt 
> with or did they just live with the earsplitting pops??
> 
> Wayne
> WB4OGM
> 
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