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Jim,

In the field, e.g. on Field Day or during emergency operation, you
might not have access to all the fancy test equipment in your shack.

If you are truly tying to use a piece of wire thrown up in a tree to
make the ubitx useful then having a reverse power indicator in the
ubitx would be very useful, especially with a qrp tuner that has no
built-in indicator.

In my go box I want my ubitx, my itty-bitty tuner, my paddle, my mic,
and a roll of copper wire. I can run off a car battery scavenged from
somewhere.

tim ab0wr

On Sun, 06 May 2018 14:59:58 +0000
"Jim Sheldon" <w0eb@...> wrote:

I somewhat agree with Tim on this, but will go out on a limb, risk
getting flamed and say I don't think a reverse power measurement in
firmware is really necessary.

In my opinion, two absolutely necessary pieces of test equipment that
should be in EVERY ham's shack are a good 50 ohm dummy load of
sufficient power rating to handle all the transmitting equipment that
ham has and a GOOD SWR bridge or better still an accurate watt meter
that can measure forward & reverse power up to the limit of the
transmitting equipment in the shack. The rig's firmware should not
be tasked with this especially since the limited NANO is being used
as a microcontroller.

The supplied NANO is already close to being severely overworked by
all the different available firmware and adding this kind of stuff
risks ruining the CW and Digital handling capability of what's
available now. I'm already seeing complaints of "This won't work or
that won't work in so-and-so's version of software" regarding a
number of things on this group. Adding more bells and whistles to
existing software for the NANO will just tend to make this worse.

Jim Sheldon, W0EB

------ Original Message ------
From: "Tim Gorman" <tgorman2@...>
To: [email protected]
Sent: 5/6/2018 9:43:08 AM
Subject: Re: [BITX20] ND6T AGC implementation for uBIT-X

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.

On Sat, 05 May 2018 15:52:36 -0700
"Jerry Gaffke via Groups.Io" <jgaffke@...> wrote:

Kees,

Consensus on the EMRFD yahoo group was that the ebay AD8307's worked
fine:

Some posts there are guessing that when boards get autostuffed from
reels there are often a few parts remaining at the end of the reel,
and the ebay sellers make the remnants available cheaply. Though if
that were truly the case, I'd expect more parts to get sold at 95%
off list price like that.

Diz already has a Stockton/TandemMatch kit at what I think is a
reasonable $12 plus shipping:
Shipping probably has to
be more than $0.70 because of the toroids. Uses 1n5711 schottky
diode detectors.

I mentioned here that I was planning to substitute a couple AD8307's
but Arv convinced me to first try biasing the 1n5711's to make them
more sensitive. /g/BITX20/message/47628
You probably already saw that, it's in this same thread.

I wrote Nano code for the Tandem Match to display forward and
reverse power in Watts, also SWR. but it's also a major rewrite of
all the uBitx code and I got lost in the weeds fiddling with other
stuff for a few weeks. I'll try to get my code going in the next
few days. The AD8307's would give more dynamic range, but I think
the 1n5711's with bias will be plenty polite. Displaying Watts and
SWR from the AD8307's linear-in-dB output would be slightly more
difficult on our computationally challenged Nano. I'm planning to
use A6 and A7 for the bridge, move the paddle to digital pins D0 and
D1 (which are currently unused except when downloading firmware).

Anybody worried about smoking their expensive RD16HHF1 FET's could
use the reflected power reading to shut down the transmitter when
their EFHW antenna falls to the ground in the wind. ;-)

Jerry, KE7ER

On Sat, May 5, 2018 at 01:30 pm, Kees T wrote:

I just uploaded the current AGC and Click kit requests. This list
is to help me asses demand so I can have the correct sets of
parts ready. There does not appear to be much demand for boards
only, just complete kits.

I'll post prices later, when I receive the boards and some
testing is done.

I was looking into Don's ND6T Polite Antenna Tuner, but there
does not appear to be much interest and using it effectively may
be a problem, so it's out. I did receive a request for a "Power
Level Upgrade" kit but decided against that because there is a
whole lot of testing to be done when you get into RF
Amplification.

What may make sense, unless it's already out there as an add-on
upgrade kit, is a Power/SWR capability using a simple Stockton
Bridge and a couple of AD8307's. I'm quite familiar with the
bridge and the AD8307 parts are getting really cheap <$0.50
each. Wonder if those Chinese parts are usable at QRP specs ?
Would need two analog inputs on whatever
microcontroller .......and, of course, the ever present
requirement for *someone* to provide support firmware.

73 Kees K5BCQ