PMK Keyer from Midnight Design Solutions

 

This is my build of the PMK Keyer.

On July 7th of this year I posted on qrptech@groups.io a message that I was in the mood for building a keyer and I asked for favorite circuits from everyone. No one mentioned the PMK Keyer from Midnight Design Solutions. While I was looking up keyer circuits I found this circuit design by Dave Benson K1SWL. I already had three Picos in stock in my junk box, so I went ahead and ordered the pcb along with some prototype boards and headers for experimenting with the Raspberry Pi Pico. George Heron N2APB kindly included a BOM to order all the parts from Mouser on his web site. That saved me a lot of time! 

https://midnightdesignsolutions.com/pmk/

The hardest part of this build for me was getting the right female headers installed for the Pico on the PMK pcb. At first I used some headers from Adafruit, but they were not tall enough and the soldered male pin headers on the Pico were not going deep enough into the female headers. Luckily, I have a Hako FR-301 de-soldering gun and I was able to desolder the Adafruit female headers with no problem. Next time I will be more careful and do better planning! :)

Building the PMK keyer went smoothly and the only confusion I had was with the Setup mode and Operational mode of the keyer. I asked George some questions and he was able to give me the information I needed to understand how everything worked.

PMK discussion, news and support are available at https://groups.io/g/cwtd

This is a nice keyer and for me it was a easy build. The firmware is written in MMBasic and for me it is easier to understand than MicroPython. Using a terminal program called Tera Term to access the firmware and to Setup the keyer had a cool retro vibe!

I want to thank George and Dave for making this keyer available. Now I am motivated to see what other projects I can come up with using the Raspberry Pi Pico!

73,

Chaplain O. Alan Jones, USA Retired

N8WQ

NorCal 80/40/20A Transceiver Build Project

 

Sorting Parts for Power Supply Stage

Back in 2017 I built a NorCal 40A Transceiver using a beta pcb that was given to me. My transceiver works but I was never happy with its performance. So I decided to build another 40A, 80A, and 20A in unison as a learning experience and to have fun! I am using the NorCal 40A Revision 2.0 pcb that is archived on the qrptech@groups.io forum in the Files section.

This is my test jig I use for building stuff.

Back in May of 2019 I decided to build a test jig to make it more user friendly when testing the circuits I built. A few days ago I added a homebrew audio amp module so I don't have to tie up another audio amplifier in the shack.

Power Supply and Audio stages pass the testing phase. 

This is my NorCal 40A pcb.

The next stage to build is the AGC and Mute circuits.

More to follow...

August 13, 2021

Alan Jones

N8WQ

Color Code Charts

Recently I discovered a web site that is really cool. It is called AmericanRadioHistory.com. I was reading the 1970 issue of Electronics Installation & Servicing Handbook when I stumbled onto this color code chart that I thought I would share.

https://www.americanradiohistory.com/Archive-Hobbyist-Specials/Electronics-Installation-Servicing-Handbook-1970.pdf

Go to page six and you will find a Color Code Chart. I printed a copy to put in a binder that I keep in my lab called Construction Techniques. The older I get the more I tend to forget things and the binder is a great way to keep important information at my finger tips.

73,
Alan Jones
N8WQ

Going Digital - Journal of Power Management

Thanks to the rain yesterday, by the time I made it out to my mailbox, my paper copy of the Journal of Power Management was wet. Immediately I tried to pull apart carefully the pages before they got stuck. I ended up pulling out both staples and scattered each page around my living room to dry. This morning, as I was puting the dry journal back together, I noticed on page two the following:

"To reduce paper use, Power by Linear Journal is going digital and will no longer be regularly delivered as a printed publication. To ensure that you receive electronic delivery of the latest Journal to your email inbox, check your MyAnalog account. Make sure you have checked "Power by Linear" under the "Resources > Newsletters" in the settings for your account."

Go to www.analog.com to update your free subscription.

Design First--Build Second

IF Amplifier Test Build

During the month of November I stumbled onto a Youtube channel run by Charlie Morris ZL2CTM. I was immediately impressed with Charlie's build philosophy: plan your circuit, consult datasheets, do the math, build and test!

Towards the end of Spring 2018, I got the bright idea of building a rig from scratch and making it a summer project. But I quickly got bogged down in the design phase of my project. I never made it past the local oscillator! :)

Thanks to Charlie's excellent teaching skills, I now have a road map that I can follow on future projects. Head over to Charlie's channel and see what he is up to. 

https://www.youtube.com/channel/UCSNPW3_gzuMJcX_ErBZTv2g

Right now I am five stages behind on his "Homebrew MC1350P based SSB Rig" and my next step is to build the RF Amplifier stage. But before I do that I am thinking about building the "8640-Jr Test Oscillator" that I never got around to building in the Fall of 2015.

73,

Alan Jones, N8WQ

A New Soldering Iron

This year at the Dayton Hamvention 2012 gathering I decided to buy myself a new soldering iron. I read reviews of the Hakko 888 throughout the year and I decided that if I found one at the Hamvention I would buy it! I was pleasantly suprised to discover that B&D Enterprises had Hakko soldering equipment for sale. Without hesitation I plopped down $105 and walked away with a Hakko FX888 soldering iron and five extra soldering iron tips.

This soldering iron replaced my old faithful Weller WES51 soldering station. I like the Hakko FX888 even better and I look forward to using it for many years to come.

The Improved Neophyte Receiver: Part 2

I searched my archives for a suitable S-Meter circuit and it turns out that I had one in my Project Box. I have a Project Box that I keep kits in for future needs. One of the kits that I had was the Kanga Products "Audio 'S' Meter." The box was down in my basement and I had completely forgotten about it.

According to Kanga Products,
"Most homebrew receivers and transceivers lack any form of 'S' meter. They are not difficult to build but finding a suitable circuit that works is often a problem. This circuit is based loosely upon one from Doug DeMaw W1FB. The circuit samples the audio of the receiver after the detector, but before the audio volume control. The signal is amplified and rectified to give a DC voltage that varies according to the level of audio."

The enclosure style I have chosen for my receiver is to allow me to easily modify my circuitry until I have locked down my choices for performance and usability. I simply used a block of wood and a piece of artist board that has clay in it to build the reciever chassis. As you can see from the front of my receiver the design is constantly evolving. Do you see the 4 holes in a rectangle shape? I was going to mount the S-Meter circuit there but the spacing was a little too tight and it was interfering with the main tuning capacitor. So I decided to mount the main receiver board vertically and then attach the S-Meter board to one corner of the receiver board.

The next modification I want to make to my 40 Meter receiver is to add a digital frequency dial.

Al
N8WQ