[ARC5] [Milsurplus] Carbon mic pops

[AKLDGUY .]

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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