Re: Fixed level audio too low on data port?
- Good point Joe...that would do the trick too.
BUT...two things to be aware of:
1. The "typical" soundcard microphone input is setup for an electret
mic. So the stereo plug is wired thus: tip=mic input, ring=electret
bias voltage (typ. 2-5V), sleeve=ground. When hooking up to your
speaker/aux audio out, you will very much want to use a MONO plug at
the mic input of the soundcard. This externally shorts the electret
bias voltage (there's an internal current-limiting resistor in the
soundcard, so no worries there) and keeps it out of your radio. Maybe
all audio outputs are AC-coupled but I wouldn't count on it... :-)
2. Double-check the output impedance specification of your audio
source. The "packet", fixed-level outputs should be OK since they're
generally rated at 10koh out. However, using an audio output designed
for minimum distortion at 4-32 ohms (e.g., speaker output) may give
poor results, as the distortion and bandwidth characteristics of the
audio source may be quite different when driving the 10koh-30koh
impedance of the mic input.
Not that not heeding these two points will yield poor results, but
things to consider in the interfacing.
--- In FT100@yahoogroups.com, "Joseph A. Counsil" <counsil@r...> wrote:
> I experienced the same low audio level problem while using WSJT
> software (but NOT with MixW, HamScope, MMSSTV, etc.). My solution is
> that while using WSJT, I feed the audio into the MIC input on the
> sound card, rather than the LINE input. The MIC input sensitivity
> (input gain) is much higher, and I have plenty of head room for input
> level adjustment. I'm running an old ISA Sound Blaster-16 sound card.
> --- In FT100@yahoogroups.com, "Scott Townley" <nx7u@a...> wrote:
> > Hey Bruce,
> > It occurs to me that the 6-pin miniDIN "packet" interface is
> > standardized, actually.
> > I have two other radios with the same capability, and the 1200bps
> > 5, used for AFSK) port on all of them are specified 300mV/10koh.
> > Since the FT-100 manual gives 2 "votes" to 300mV/10koh and only 1
> > "vote" to the other, I am pretty confident that the 300mV/10koh
> > > results are the same. Setup is working and have made several
> > > FSK441 qso's now but the low audio is bugging me. TX audio level
> > > port appears fine and getting good signal reports.