My problem is that my tuner, a homebrew z-match type, doesn't have an
swr meter. When operating portable, with a compromise antenna, knowing
the swr doesn't matter much unless you have that "extra" box normally
called a tuner. 

I'm just saying that knowing the swr doesn't matter much to me,
especially if it takes up more precious nano resources. All I need is a
reverse power indicator to tell when the tuner has matched the antenna.
The output power is going to be whatever it will be, there isn't much
you can do about it in the field. You don't normally adjust a tuner for
maximum output, you adjust it for minimum reflected power. 

Any random piece of wire is going to work as an antenna. The issue is
whether you can match the rig to the antenna using a tuner. 

tim ab0wr



On Sun, 06 May 2018 07:57:01 -0700
"Jerry Gaffke via Groups.Io" <jgaffke@...> wrote:

The goal is whatever we want it to be.

Showing SWR on the uBitx makes it useful for verifying an antenna
system is working without having to lug about an extra box,
especially when operating portable. If it costs an extra $3 in parts,
I'm fine with adding it to the rig.?

If you have a tuner that already shows SWR and forward power,
and your antenna needs a tuner anyway,
then your goal may be different.

Jerry, KE7ER

On Sun, May 6, 2018 at 07:43 am, Tim Gorman wrote:

Jerry,

What is the goal here? Is a wattmeter function really needed inside
the ubitx? Or would it be better as an external attachment that can
be used with other equipment?

For me, measurement of the reverse power is the primary measurement
needed inside the ubitx. It is useful for adjusting an external
tuner and for deciding if the ubitx is at risk from a bad load. I
am using the simple circuit at the nd6t site to get the reverse
power measurement. Right now I am using an external analog meter
but I have an adafruit ADS1015 that I am going to use when I get my
ubitx working again. I am using a little 4x4 breadboard to make an
I2C bus expander and the ADS1015 will feed into this along with the
I2C lcd.

Coding for this is extremely simple. You don't even have to convert
to volts. Just display the reading from the ads1015. As it goes
down you know the reverse power is going down. If you want to do it
with an analog pin on the nano you can do that too.

Just my 2cents. FWIW.