[Amps] W8ZR Autotune Amplifier Progress Report
Joe Subich, W4TV
lists at subich.com
Wed Dec 23 12:43:06 EST 2020
> Much better ways are available. N1MM, for example, puts a lot of
> relevant information out via UDP, and the OTRSP (Open Two Radio
> Support Protocol) is also available for serial comms or USB, via
> USB-to-serial converters.
That only works if one has a micro-controller and operating system
that supports a TCP/IP stack. I doubt that the Propeller is that
sophisticated.
73,
... Joe, W4TV
On 2020-12-23 11:45 AM, N4ZR wrote:
> Please, no more parallel port stuff - that's so 1990's, and increasingly
> hard to find. Much better ways are available. N1MM, for example, puts
> a lot of relevant information out via UDP, and the OTRSP (Open Two Radio
> Support Protocol) is also available for serial comms or USB, via
> USB-to-serial converters.
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> On 12/23/2020 10:53 AM, Jim wrote:
>> Jim
>> What about an input for band selection to help speed up auto tuning.
>> Such an input would be from a logging program (parallel port on a PC),
>> or simply band data from a transceiver in the form of a single input
>> line (active low) per band, or the Icom band data voltage, to "preset"
>> the band switch but also the tune and load caps.
>>
>> Looks great, and thanks for the timing on this! I'm thinking that I
>> want to build a remote station, but not being forced into using a
>> solid state amplifier.
>>
>> Icom band data voltage:
>>
>> 10 0V
>> 50 (unofficial) 1.0 ~ 2.0V
>> 28 & 24 2.0 ~ 3.0V
>> 18 & 21 3.0 ~ 4.0V
>> 14 4.0 ~ 5.0V
>> 7 5.0 ~ 6.0V
>> 3.5 6.0 ~ 7.0V
>> 1.8 7.0 ~ 8.0V
>>
>>
>> Thanks
>> 73
>> Jim W7RY
>>
>> On 12/19/2020 8:40 PM, MU 4CX250B wrote:
>>> Hi gang
>>> Here’s a response I made to a question from my friend Paul W9AC. Paul
>>> and I
>>> have known each other for years, and he is a very savvy, technically
>>> competent ham (as you probably already know). I hadn’t intended on
>>> sharing
>>> this exchange with the List because it’s pretty technical, but I’m
>>> happy
>>> to go do so.
>>> 73,
>>> Jim w8zr
>>>
>>> Sent from my iPhone
>>>
>>> Begin forwarded message:
>>>
>>> *From:* Jim Garland <4cx250b at miamioh.edu>
>>> *Date:* December 19, 2020 at 5:14:17 PM MST
>>> *To:* Paul Christensen <w9ac at arrl.net>
>>> *Subject:* *Re: [Amps] W8ZR Autotune Amplifier Progress Report*
>>>
>>> Good question, Paul. I'm using five of the eight available
>>> microprocessors, or "cogs" as Parallax calls them. Currently, COG0
>>> is the
>>> "base" cog, which manages the entire program and offloads chores to
>>> other
>>> cogs when necessary or convenient. I've loaded COG0 with some chores
>>> I'll
>>> eventually direct elsewhere. For example, at the moment when RF at
>>> the amp
>>> input is detected and authenticated (to verify it's in a valid range,
>>> that
>>> the amp is on-line, etc.), then the bandswitch, tune, and load caps are
>>> moved sequentially. That works fine for the tune and load caps, since
>>> they
>>> adjust in a fraction of a second, but depending on circumstances, the
>>> bandswitch may take a couple of seconds. My plan is to move that
>>> tuning to
>>> other cogs so the three steppers readjust simultaneously. Ditto for the
>>> initialization routine which zeros the steppers at power up and
>>> starts the
>>> warmup countdown. I want to add some timing features to a dedicated
>>> timing
>>> cog, COG2, along with an intelligent power up and power down routine for
>>> blower control and temperature measurement. All COG2 does now is count
>>> seconds and blink an LED to tell me the circuit is working.
>>>
>>> COG7 is dedicated to computer interfacing. It outputs and inputs serial
>>> data to a USB port, which is used to download firmware into the
>>> Propeller
>>> and to display messages and data onto a PC monitor. It also controls the
>>> 4-line LCD, as shown on the YouTube video.
>>>
>>> COG 1 is dedicated to manual tuning, including managing the
>>> band-stacking
>>> register. Implementing manual tuning turned out to be my hardest
>>> programming challenge. Reading and updating memory when the tuning
>>> buttons
>>> were pressed, along with the Save feature, interfacing manual tuning
>>> with
>>> autotuning so the two modes didn't fight each other, etc., took a
>>> couple of
>>> months to work out.
>>>
>>> COG3 is a system frequency counter, which runs all the time. It detects
>>> and measures RF at the amplifier input with a sensitivity of 250uV and a
>>> resolution of 1 kHz, then passes the measurement as a variable to COG0
>>> which makes sure the frequency is in a valid ham band. The frequency
>>> counter works better than I expected. I initially had planned to use a
>>> Schmitt trigger to clean up the input RF, but didn't need to do that. I
>>> measure every signal twice, with measurements spaced out 100mS, and
>>> require
>>> both measurements to agree before deciding the result is valid.
>>>
>>> I made a design decision early-on not to arbitrate or control QSK and
>>> ordinary T/R switching. There's plenty of spare capacity in the
>>> Propeller
>>> to do that, as well as to measure RF power, SWR, plate voltage and
>>> current,
>>> grid current and safety trip features, but for now I'm not going down
>>> that
>>> road. Most of these extra functions are easily controlled with
>>> standard or
>>> dedicated circuitry (e.g., we each have our own QSK designs) and already
>>> exist in commercial amplifiers. By avoiding them in this project,
>>> it's easy
>>> for other builders to use the Propeller as an add-on to existing
>>> amplifiers. All that's really needed is to sample the RF at the input of
>>> their amplifier, and mechanically connect stepper motors to the
>>> switch and
>>> variable capacitor shafts. It's tempting to look at all the available
>>> programming space and start adding features, but for now anyway I
>>> want to
>>> make the project as easy to implement as possible!
>>>
>>> I hope to start laying out a PCB based on my breadboard within the next
>>> week or so. The basic circuit seems to work well, so I don't foresee any
>>> major problems lurking in the shadows. Famous last words, probably.
>>> 73,
>>> Jim W8ZR.
>>>
>>> On 12/19/2020 3:12 PM, Paul Christensen wrote:
>>>
>>> "The PX32A is a sophisticated device containing eight fully independent
>>>
>>> 32-bit microprocessors that share 31 read/write IO ports and a common
>>> memory
>>>
>>> for storing variables.
>>>
>>>
>>> Jim, what amplifier functions are being divided across the eight
>>> independent
>>>
>>> microcontrollers? For example, does one exclusively manage the T/R
>>>
>>> function? Perhaps another is dedicated to monitor power supply
>>> parameters,
>>>
>>> etc.?
>>>
>>>
>>> My 8877 amp uses an Arduino Mega 2560 but I cram the code for all
>>> functions
>>>
>>> into one loop. To make this work with one microcontroller, delay
>>> commands
>>>
>>> are invoked by comparing time registers. The main loop never stops
>>> running
>>>
>>> at full speed no matter what delays are present.
>>>
>>>
>>> Within the constraints of memory, it's possible to load unrelated
>>> programs
>>>
>>> into the same microcontroller.
>>>
>>>
>>> Paul, W9AC
>>>
>>>
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