Jim Weir: RST-442 intercom good

[Leo]

Jim and others interested,
I previously said that normal voice into the mikes on the headsets I
installed in my new homebuilt wouldn't easily break the squelch of the newly
built RST-442 Intercom I had also installed. Yesterday a friend used his
Sigtronics headset for the flight and the squelch was opened instantly. So
the cause of the problem was the inadequate output of the electret
microphones on the low cost headsets I had installed.
Thanks for a good product.
Leo

[RST Engineering]

It usta was be that headsets had a "mic level" control on them so that you
could adjust the output of the microphone on a headset to be somewhat
standard across all makes and models of headset. It could compensate for
the fact that your particular voice was above or below a "normal" level.

Somebody somewhere decided that it would save a dime a headset to eliminate
this feature and we have all been suffering since. If we design an intercom
for a "normal" voice/headset level and then a particular headset is too LOW,
we have volume and squelch problems. If it is too HIGH then it distorts on
voice peaks. It really cobs up the works.

Glad you have found what the "problem" was.

Jim



"Leo" <LeoPowningatYahoo.com> wrote in message
...
> Jim and others interested,
> I previously said that normal voice into the mikes on the headsets I
> installed in my new homebuilt wouldn't easily break the squelch of the
> newly built RST-442 Intercom I had also installed. Yesterday a friend
> used his Sigtronics headset for the flight and the squelch was opened
> instantly. So the cause of the problem was the inadequate output of the
> electret microphones on the low cost headsets I had installed.
> Thanks for a good product.
> Leo
>

[Morgans]

"RST Engineering" > wrote in message
...
> It usta was be that headsets had a "mic level" control on them so that you
> could adjust the output of the microphone on a headset to be somewhat
> standard across all makes and models of headset. It could compensate for
> the fact that your particular voice was above or below a "normal" level.

Would it be possible to make a widget to plug in, between the headset (mic)
and audio panel, that would provide an adjustment, to raise or lower the mic
output? Would you be interested in making it a Kitplanes column? (or other
vehicle to bring it to the public)
--
Jim in NC

[RST Engineering]

If you bias the microphone with a 470 ohm resistor from any voltage from 8
to 20 volts, you should get an AC voltage at the bias point of half a volt
peak to peak with a "normal" voice. This is a field measurement, and not
the exact RTCA specification, which goes on to specify a lot of other crap
that is pretty meaningless.

"Normal" is not defined.

Jim



"karel" > wrote in message
...

> Jim,
> While we're on this subject, what are the specs for a "standard"
> microphone input (i.e. from aheadset) on an audio panel?
> I know I could google it out or search your website,
> but couldn't resist asking as the subject floated along...
> TIA!
> KA
>
>