[Milsurplus] [ARC5] Carbon mic pops

[hwhall at compuserve.com]

>R-37 and C-16 have an RC time constant of 50 mS. Check that a) both are fitted b) C-16 is good. 
 

Both are present and C-16 is a new component.

Wayne

 WB4OGM

 

-----Original Message-----
From: AKLDGUY . <neilb0627 at gmail.com>
To: ARC-5 List <arc5 at mailman.qth.net>; milsurplus <milsurplus at mailman.qth.net>
Sent: Wed, Nov 30, 2016 4:34 am
Subject: Re: [ARC5] [Milsurplus]  Carbon mic pops



R-37 and C-16 have an RC time constant of 50 mS. Check that a) both are fitted b) C-16 is good. You can tell whether it's good or not by charging it and watching the voltage across it decay when the source voltage is removed.



73 de Neil ZL1ANM









On Wed, Nov 30, 2016 at 8:34 PM, Hubert Miller <Kargo_cult at msn.com> wrote:


What’s the voltage available to the mic element BEFORE the microphone is switched in, has mic current flowing?
In other words, does it soar with no ( mic ) load?
-Hue
 
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net]On Behalf Of hwhall at compuserve.com
Sent: Tuesday, November 29, 2016 10:45 PM
To: arc5 at mailman.qth.net; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] [ARC5] Carbon mic pops

 

Attached is the schematic of the mic circuit & amp that I'm looking at. The mic internal wiring looks like just a set of PTT contacts in series with the carbon mic button + the small cap across the mic button.

The primary of T-4 has no current thru it until one of the mics is keyed, then suddenly current flows thru primary & carbon mic, inducing a transient in T-4 that appears as a loud initial pop in the headphones. I don't see how they prevented this pop from happening every time a mic was keyed.

By hitting Send I'm about to remind myself whether these forums allow images attached.  :-\




Wayne
WB4OGM





 



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