[Amps] W8ZR Autotune Amplifier Progress Report

[N4ZR]

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
>>
>>
>> _______________________________________________
>>
>> Amps mailing list
>>
>> Amps at contesting.com
>>
>> http://lists.contesting.com/mailman/listinfo/amps
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps