[arm-allstar] How do you determine proper Rx resistor values

[Krys Beal]

Is there any concern about isolation on the Tx side? I noticed there's no
cap shown in the reference drawing. Thanks for bearing with me on this one,
team. I'm sure I'll have more questions as the components arrive

Krys
K3EAL


On Mon, Feb 27, 2017 at 3:36 PM David McGough <kb4fxc at inttek.net> wrote:


BTW, if you're going to get new potentiometers, ideally try to find the
"audio taper" (logarithmic resistance) variety....They'll be easier to
set.

73, David KB4FXC


On Mon, 27 Feb 2017, "Krys Beal via arm-allstar" wrote:

> Thanks Doug. I'll pick up a couple of 50K pots. Is the 10uF capacitor that
> is also listed a fixed value?
>
> On Mon, Feb 27, 2017 at 10:44 AM "Doug Crompton via arm-allstar" <
> arm-allstar at hamvoip.org> wrote:
>
> > Krys,
> >
> >   Resistor values have nothing to do with the Nano but rather the audio
> > in/out of the USB audio FOB which would be used in conjunction with the
> > Nano for control. The audio is adjusted with the RX/TX gains in
> > simpleusb-tune-menu and both have a range of 1 to 999 with a median
value
> > of 500. The default values are set to 500 when you initially setup. In
> > addition there is a parameter in simpleusb-tune-menu called rxboost
which
> > can boost the level by 20db when on. It is on by default.
> >
> > It is also important to note that RX is what the node radio receives
when
> > you transmit to it from another radio and TX is what you hear on that
radio
> > when your node is transmitting. So you have to look at it in the
> > perspective of the node radio not the radio/handheld, etc. you use to
talk
> > to your node.
> >
> > Because there are so many different radios and sound FOBs used with
Allstar
> > it often becomes necessary to add additional attenuation in the form of
a
> > resistor or resistive divider in series with the audio leads.
Unfortunately
> > there is no list of values for a particular combination. I would start
out
> > with 10K on both the TX and RX sides. If the simpleusb-tune-menu audio
> > settings are no pegged or very close to one extreme or the other then
you
> > are probably OK. At least one commercial FOB has pots and that might be
a
> > way to go. Use a couple of 10K or higher pots on the TX and RX lines and
> > with the SW values set at mid point adjust the pots. Then you have
plenty
> > of SW adjustment if you desire.
> >
> > If you want to use fixed resistors I would start out with 10K. For the
> > Baofeng 888 we use 10K for both the RX and TX and it works out well
keeping
> > the settings within +-200 of the midpoint. Put the resistors in a place
> > where they can easily be changed if necessary.
> >
> > I hope that did not confuse you. If you have any more questions let me
> > know.
> >
> >
> > *73 Doug*
> >
> > *WA3DSP*
> >
> > *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
> >
> > On Mon, Feb 27, 2017 at 9:04 AM, "Krys Beal via arm-allstar" <
> > arm-allstar at hamvoip.org> wrote:
> >
> > > I've recently purchased the preassembled HamVOIP Nano interface. While
> > > looking at the Rx portion of the interface schematic there is a note
> > > indicating that resistor values indicated are for the DMK URI, and
should
> > > be adjusted for my specific application. My plan is to use a TH-9000D
> > > modified per the writeup on the HamVOIP website. How do I determine
the
> > > proper resistors to use for this application.
> > >
> > > 73
> > > Krys Beal
> > > K3EAL
> > > _______________________________________________
> > >
> > > arm-allstar mailing list
> > > arm-allstar at hamvoip.org
> > > http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> > >
> > > Visit the BBB and RPi2/3 web page - http://hamvoip.org
> > >
> > >
> > _______________________________________________
> >
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> > arm-allstar at hamvoip.org
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> >
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> >
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