Re: Re: Discriminator tap question

Well, use a bigger cap then. Personally, I would never run audio 
straight to a PC/LT. You never know what will happen. I guess you could 
try it and see what happens. I guess replacing a sound card is cheaper 
than replacing a motherboard or a PC/LT. Especially if you are using the 
onboard sound chip. LoL I always use a 1:1 audio transformer to prevent 
ground loops and DC as well. At times I have had to add a 5k oHm pot to 
adjust the level - more convenient to quickly turn a knob than messing 
with PC/LT sound mixer sliders and a mouse.

BTW, are you using POSAG or something like that? I messed with that kind 
of stuff ~15 years or so ago. Boring after a few minutes. Yeah, you'll 
see lots of phone #'s and very short messages. Don't remember if it 
legal or not but still boring, at least to me anyway. Kinda like the 49 
mHz baby monitors and 900 mHz wireless phones. Listening to the 
PD/FD/Mil and some local VHF is a lot more interesting at least to me.

Don KPC6NDB
Upland, CA
34.10 -117.63 1250ft
R-75 w/250Hz 2x R-71A w/250Hz R-70
Perseus SDR-IQ FUNcube Dongle Pro+
FRG-100B SR-AF & LPF DSP599zx
MFJ-784B HD-1418 AF-1 MSB-1
PA0RDT Mini-Whip x2 @ 25ft
RYO Active Antenna @ 25ft
LFL1010 ALA100L x2

On 07-Mar-13 01:37, Bigjed wrote:
> OK.A bit of a conflict here then.Question:Would I get away with using
> nothing at all?Just a wire from the tapping point to a phono socket
> mounted at the rear of the radio.No danger of headphones being plugged
> into that.I intend to use the socket for the purpose of decoding pager
> signals and the like and want a nice clean signal.
>
> Gerry.
>
> --- In [email protected]
> <mailto:UnidenBC780XLT%40yahoogroups.com>, OldOne <oldone45@...> wrote:
>  >
>  >
>  >
>  > I normally use a 1K resistor as an isolator incase some one plugs a
> 32 ohm
>  > earpiece into the socket and almost shorts the discriminator point to
> ground.
>  >
>  > Also do not use a 0.01 uf cap as DC blocking if you want a clean data
> waveform
>  > out as it will phase distort the low frequency squarewaves output for
> data
>  > decoding. If you must block the DC use a least a 1.0 uf 50v
> monolithic cap
>  > when feeding into a 10k load of the sound card input.
>  >
>  >
>  >
>  > On 06 Mar 2013 08:57, Bigjed wrote:
>  >
>  > --- In [email protected]
> <mailto:UnidenBC780XLT%40yahoogroups.com>, Don <stb55@> wrote:
>  > >>
>  > >> Usually it is advisable to use a small value ceramic cap like 0.01
> uf to
>  > >> block DC - no resistor needed - that would drop the signal some.
>  > >>
>  > >> Doesn't hurt to use coax like RG-174 but not really needed. Depends on
>  > >> how much you want to put into a project labor wise. Also I always
> think
>  > >> about resale value - like putting holes for switches on a front panel.
>  > >>
>  > >>
>  > >> Thanx Don.I've seen a couple of conflicting articles re this.Some
> recommend the resistor with coax,some just a wire from the tapping point
> straight to a phono socket on the rear of the radio.I've not seen the
> ceramic cap mentioned yet tho'.is that just connected in series,like the
> resistor would be?
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------------------------------------

If you have come here to find out about the Uniden BC-780 you have come to the right place! In fact the discussion of the BC-780 is the only acceptable topic on this list. Please. I hope this is clear to all group members.