I found a schematic of the Turner +3 mic online. It is more advanced than you should think as Turner already implemented compression in the late seventies. They called the compression technique “modu-guard”. It is a rectifier circuit that rectifies the audio and sends a DC attenuation signal back to Q3 in the source of the FET amplifier.
To use the CG 3000 antenna tuner for remote operation there is a control box (CTU) that could be purchased from the manufacturer. Some people want to make such a control box themselves. Here is the schematic info.
Thanks to https://sp5kab.pl/pl/sterownik-cg-3000-cg-antenna-tuner-control-unit for doing the work with determining the schematic
SGC has made an automatic antenna tuner that has several smart ideas implemented. It uses a phase detector to be able to know if the load is capacitive or inductive. The design uses a RF mixer and several clever multifilar transformers. SGC also included several practical antenna antenna ideas in their manuals. I have uploaded the information here. Credit: SGC
Manual 1 PDF1
Manual 2 PDF2
Manual 3 PDF3
K9EQ made a good description of the Icom AH-4 antenna tuner including the signalling interface from the radio to the tuner and from the tuner and back to the radio. I did take the liberty to post the pdf here. Credit: K9EQ
AH-4_Design_and_OperationDJ0IP has collected a few interesting HF RX BPF designs. These are fairly narrowband. With todays EMI problems (that NRRL and the other radio amateur organizations seem to care little about), using filters such as these can have an improving effect. Not only for noise emanating inside the amateur radio bands but specifically noise outside the bands. Why?: broadband noise from LED switchers, SMPS, Solar arrays etc often cover a wide HF spectrum, also outside the amateur radio bands. If the input of a HF receiver lets in noise energy also from those frequency ranges outside this will often be altered in slight non linearity in the input stages of the receiver and turn into noise inside the amateur radio bands. I have seen this with comparing switching noise in the 40, 20, and 10m bands and just outside the bands. My FT2000 transceiver switches out the preselector filter when the RX is just outside the amateur radio bands. This results in quite significant noise increase from LED switchers, SMPS etc. while it is fairlig quiet inside the amateur radio band, indicating that the preselector filter indeed has a good effect. For radios that doesnt have this built in, these filters can be of interest.
Download the PDFs from the links below –>
I purchased a cheap china made ultrasonic cleaner. Here is a teardown and review video where I also touch the electrical safety aspcect. The safety grounding was ok so as long as you use a receptacle with a ground connection and a protective fuse (with earth fault detection and isolation) it should be ok. I wouldn’t recommend spilling fluid inside the ventilation holes though so use care.
Sometimes there is a need to locate a cable in buildings or in ground. It could be because there are many cables running in paralell without marking or that you dont know if a cable is going at all to a location you “think” it is going to. It may also be buried cables that you dont know where to dig for. In this video I show how you can use a signal generator, an AM receiver of the cheap generic type and a counter weight radial to inject a 650 KHz on a cable and later locate it.
DXheat has made a nice dxcluster site. What separates this is that you can filter on where the spot comes from (EU for example), what the spot contains (EU or DX) etc.
OKDXF published the W1FB design notebook on their website https://www.okdxf.eu/files/W1FB%20Design%20Notebook.pdf This notebook contains a lot of interesting circuits for amateur radio experimenters. Check it out.
W1FB-Design-Notebook-1Steps to Set Up SSH Key Authentication Between Windows and Raspberry Pi (So You Don’t Have to Enter the Password)
You should have generated the SSH key pair on your Windows machine (the one you’re using for VSCode).
Open PowerShell (or Command Prompt) on your Windows machine.
Run the following command to generate an SSH key pair:
ssh-keygen -t rsa -b 4096
Follow the prompts:
Press Enter to accept the default location for the key (C:\Users\<YourUserName>\.ssh\id_rsa).
Optionally, enter a passphrase, or leave it blank for no passphrase (easier but less secure).Now you should have two files in your C:\Users\.ssh directory:
id_rsa (your private key)
id_rsa.pub (your public key)You need to copy the public key (id_rsa.pub) to the Raspberry Pi so that it can authenticate you.
Option 1: Using ssh-copy-id (from Windows with Git Bash)
If you have Git Bash installed on your Windows machine, you can use the ssh-copy-id tool to copy the public key to the Raspberry Pi:
Open Git Bash on Windows.
Run the following command:
ssh-copy-id pi@<RPI_IP_ADDRESS>
Replace <RPI_IP_ADDRESS> with the actual IP address of your Raspberry Pi.
It will prompt you for the Raspberry Pi password. After entering it, your key will be copied.Option 2: Manually Copy the Key
If ssh-copy-id is not available, follow these manual steps:
Copy the public key:
Open id_rsa.pub (located in C:\Users\<YourUserName>\.ssh\id_rsa.pub) with a text editor, and copy its entire content.
Log into the Raspberry Pi:
Open PowerShell or Command Prompt on Windows, and run:
ssh pi@<RPI_IP_ADDRESS>
Enter the Raspberry Pi password when prompted.Paste the public key into the authorized_keys file:
On the Raspberry Pi, run:
mkdir -p ~/.ssh
nano ~/.ssh/authorized_keys
Paste the contents of id_rsa.pub into the authorized_keys file.
Save and exit (Ctrl + X, then press Y to confirm, and Enter).Set the correct permissions:
Run the following commands on the Raspberry Pi to ensure the permissions are correct:
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keysNow, ensure that the SSH server on the Raspberry Pi is configured to allow key-based authentication and disable password authentication (if you want to fully rely on SSH keys).
Edit the SSH configuration file on the Raspberry Pi:sudo nano /etc/ssh/sshd_config
Ensure the following lines are present and not commented out (# means commented out):
PubkeyAuthentication yes
PasswordAuthentication no (This line will disable password authentication, forcing key-based login)
AuthorizedKeysFile .ssh/authorized_keysRestart the SSH service to apply changes:
sudo systemctl restart sshTest that SSH key authentication is working by attempting to log in again from your Windows machine:
Open PowerShell or Command Prompt on your Windows machine.
Run the following command:
ssh pi@<RPI_IP_ADDRESS>
You should now be able to log in without a password prompt. If everything is set up correctly, SSH should use the key authentication, and you'll be logged in automatically.Now that SSH key authentication is working, you can connect from VSCode:
Install the Remote - SSH extension in VSCode if you haven't already.
Configure the SSH connection in VSCode:
Open Command Palette (Ctrl + Shift + P) in VSCode.
Type Remote-SSH: Open SSH Configuration File.
Add an entry for your Raspberry Pi:
Host raspberrypi
HostName <RPI_IP_ADDRESS>
User pi
IdentityFile C:\Users\<YourUserName>\.ssh\id_rsa
Connect to the Raspberry Pi:
Open Command Palette (Ctrl + Shift + P) in VSCode again.
Select Remote-SSH: Connect to Host... and choose your Raspberry Pi entry.Now, VSCode should connect to your Raspberry Pi without asking for a password each time you reboot your Raspberry Pi.
With this setup, you should no longer be prompted for a password after rebooting the Raspberry Pi!