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PA2AGA > HDDIG 01.01.00 04:49l 239 Lines 7731 Bytes #-9631 (0) @ EU
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Subject: HamDigitalDigest 99/324D
X-BBS-Msg-Type: B
>
> In fact, this is always a good thing to do. When I make
connections
> to transceivers for 9k6 modification, where AC coupling is a bad
idea,
> I always put in a small series resistor directly at the connection
point,
> to avoid damage to the transceiver when the outgoing lead is
shorted to
> ground or to small voltages like +5 or +12. Better to have some
percent
> of signal loss than a blown-out 3357.
>
> Rob
> --
>
+----------------------------------+---------------------------------
-----+
> | Rob Janssen pe1chl@amsat.org | WWW:
http://www.knoware.nl/users/rob |
> | AMPRnet: rob@pe1chl.ampr.org | AX.25 BBS:
PE1CHL@PI8WNO.#UTR.NLD.EU |
>
+----------------------------------+---------------------------------
-----+
>.
------------------------------
Date: Sat, 18 Dec 1999 21:11:14 -0500
From: "Rob" <NoEmail@NoWay.com>
Subject: Connecting sound card to Computer
Bob,
Many thanks for the info.
I understand that it is alright to fed both channels of the sound card line
input.
BUT I heard it is a different story for the MIC input. I was told that the
mic jack on a sound card is a MONO circuit but uses a STEREO JACK with one
channel carrying the audio and the other carrying a DC voltage for the mic.
It was suggested that I use a STEREO connector and ONLY use the TIP which
carries the audio. (AND DON'T USE the RING which carries the polarizing
voltage).
Since HAMS like me sometimes plug cables in the wrong jack (especially if
the mic and line input jacks are beside each other), it sounds to me like a
good idea to only use one channel carried in the tip (even if you PLAN to
connect it to the line input jack where it doesn't matter)
Any thoughts?
Rob
"Bob Lewis" <aa4pb@erols.com> wrote in message
news:83hcep$prq$1@bob.news.rcn.net...
> > I heard that it is NOT a good idea to connect both channels (Left
> and Right)
> > of the sound card's line output to the Rig's mic input. It might
> cause
> > distortion.
>
> It is NOT a good idea. When you connect the two outputs together you
> are shorting the outputs. Whether this causes any distortion depends
> on the sound card output circuit design and how well balanced the two
> outputs are. If, for example, you had the mixer balance all the way
> to one side, the dead side would attempt to short the output of the
> other. The output impedance *may* be high enough to prevent
> distortion or damage but you never know how it was designed. It's
> best not to do it and there's no advantage to it that I can think of.
> In pro audio a resistor is often inserted into each channel in order
> to provide a "resistive combiner" circuit to feed a stereo channel
> into a mono channel. With PSK31 both channels have the same signal so
> there's no reason to do it.
>
> > (On the other hand, I heard it doesn't matter whether the rig's
> > speaker output is connected to both channels of the sound card's
> line input
> > or mic input).
>
> It doesn't matter because because you are shorting two inputs. The
> load impedance drops to one-half but it's still plenty high enough
> not to overload the receiver's output.
>
> > I also heard if you just used a mono plug for the sound card's line
> output
> > (or speaker output), it will short out one of the channels and may
> cause
> > distortion. It is best to use a stereo plug and only use one of
> the
> > channels. Is this good advice?
>
> Good advice! A mono plug will short one output. It may not cause
> distortion in the other channel, but it's never good practice to
> short an output unless you know for sure that the circuit design can
> handle it.
>
>
>
>.
------------------------------
Date: Thu, 23 Dec 1999 16:49:20 -0600
From: "Rich Peet" <peet@citilink.com>
Subject: Connecting sound card to Computer
no, most sound cards are mono on the mic input. The center ring is either
not connected or is 5 volts for those with electret mics.
"D. Stussy" <kd6lvw@bde-arc.ampr.org> wrote in message
news:Pine.LNX.4.10.9912192112030.5987-100000@dns.bde-arc.ampr.org...
> Both.
>
> On Sat, 18 Dec 1999, Clifford Buttschardt wrote:
>
> > Which input, mic or line? I can not make any sence out of these
> > statements that do not define what is being said! Cliff K7RR
> >
> >
> > Sat, 18 Dec 1999, D. Stussy wrote:
> >
> > > Depends on the soundcard. Most soundcards now have stereo inputs.
> > >
> > > On Sat, 18 Dec 1999, Clifford Buttschardt wrote:
> > > > Good comments these, but I am still confused. Is the line and
microphone
> > > > inputs USUALLY stereo plugs? I think the mic input is always stereo
but
> > > > does it use the "ring" in any way? I would guess the line input
would be
> > > > mono in most cases. Is this true most of the time? Cliff K7RR
> > > >
> > > > On Sat, 18 Dec 1999, D. Stussy wrote:
> > > >
> > > > > On Sat, 18 Dec 1999, Rob wrote:
> > > > > > I heard that it is NOT a good idea to connect both channels
(Left and Right)
> > > > > > of the sound card's line output to the Rig's mic input. It
might cause
> > > > > > distortion. (On the other hand, I heard it doesn't matter
whether the rig's
> > > > > > speaker output is connected to both channels of the sound card's
line input
> > > > > > or mic input).
> > > > > >
> > > > > > Is this true? Will there be distortion?
> > > > > >
> > > > > > I also heard if you just used a mono plug for the sound card's
line output
> > > > > > (or speaker output), it will short out one of the channels and
may cause
> > > > > > distortion. It is best to use a stereo plug and only use one of
the
> > > > > > channels. Is this good advice?
> > > > >
> > > > > ...If someone were smart, the soundcard driver software could be
re-written so
> > > > > each audio channel were a different "port" thus creating a
dual-port virtual
> > > > > TNC. Of course, there would have to be two PTT circuits, two DSP
engines for
> > > > > RX, etc. Then the above situation would be moot.
> > >
> > >
> > >
> >
>
>.
------------------------------
Date: Tue, 21 Dec 1999 17:10:05 -0500
From: "Rob" <NoEmail@NoWay.com>
Subject: Connecting sound card to Computer
I am just curious. Are the big 1/4 inch stereo jacks and plugs better than
the smaller mini stereo jacks and plugs? That is, are the big stereo jacks
better designed than the smaller 3.5 mm jacks such that the big 1/4 jacks
not to"short out" some of the circuits when plugging them in and out of the
jack?
Rob
"Chris Smolinski" <csmolinski@erols.com> wrote in message
news:385F80DF.9C6816B@erols.com...
> Apple avoided this problem by using a modified (longer) plug for the
> microphone. The DC power is at the tip, but since the jack is designed
> for a longer plug, a normal plug won't reach it. The center ring is
> longer, and connects to both left and right channels, for blended mono
> recording. Yet a stereo plug could also be used, for true stereo
> recording.
>
> 73's
> Chris
> N3JLY
>
>
> Rob wrote:
> >
> > IMPORTANT -- CORRECTION -- PLEASE READ
> >
> > The mic jack on a sound card is a MONO circuit but uses a STEREO JACK
with
> > one channel carrying the audio to the sound card from the mic and the
other
> > channel carrying a DC voltage to power a mic.
> >
> > I made a big mistake. THE TIP OF THE MIC CONNECTOR CARRIES THE DC NOT
THE
> > AUDIO AS I SUGGESTED IN MY LAST POSTING!
To be continued in digest: hd_99_324E
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