WFC RF VLF Fully Automatic Tuner Build
I am starting this thread to build the WFC Fully Automatic Tuner.

This guide will help you understand and build a fully automatic tuner for a Water Fuel Cell (WFC) system.

The tuner is a PCB board placed: 

• After the transistor or switch 
  After any transformer or choke 
  Before the blocking diode and the WFC

Purpose:
The tuner measures the circuit's power reflection and automatically adjusts to minimize it, achieving resonance or near-zero power reflection for an LC-matched tank circuit. Given the WFC's impedance can vary (e.g., around 10 ohms as bubbles form), the tuner ensures efficient power transfer by adapting to these changes. 

Since we're in 2025, we can leverage modern components and microcontrollers to create a fully automatic solution—no more manual tuning with swiper chokes!

Purpose and Placement of the Tuner

Purpose:
The fully automatic tuner ensures that the power from the transmitter (or power source) is efficiently delivered to the WFC by matching the impedance. It continuously monitors and adjusts to minimize power reflection, keeping the circuit in resonance at 5 kHz despite changes in the WFC's impedance (e.g., due to bubble formation).

Placement: 
After the transistor or switch 
After any transformer or choke 
Before the blocking diode and WFC

Components of the Fully Automatic Tuner
A fully automatic tuner requires several key components that work together to adjust the circuit without manual intervention. Here's what they are and what they do:

Inductors (L): 
These are coils of wire that store energy in a magnetic field. 
They add "inductive reactance" to balance the circuit. 
For your setup: You'll need large inductors (e.g., 100µH to 10mH) rated for 10A and 1200V. 
Example: Bourns 1140-102K-RC (1mH, 10A).

Capacitors (C): 
These store energy in an electric field. 
They add "capacitive reactance" to balance the circuit. 
For your setup: You'll need high-voltage capacitors (e.g., 0.1µF to 10µF) rated for 1200V. 
Example: Vishay MKP1848C series.

Relays or Switches:
These act as high-power switches to connect or disconnect inductors and capacitors. 
Controlled by the microcontroller to test different configurations. 
For  setup: You'll need relays rated for 10A and 1200V. 

Example: Omron G7L-2A-TUB (25A at 250V AC; verify DC ratings) or solid-state relays like Crydom D1D40 (40A, 100V DC; use multiple in series for 1200V).

Microcontroller: 
The "brain" of the tuner. 
It measures the mismatch and controls the relays to adjust the circuit. 
For your setup: Use a microcontroller like an Arduino Uno or STM32, with custom programming.

Measurement System: 
Instead of a traditional SWR bridge (which is for radio frequencies), you'll need a system to measure impedance or reflections at 5 kHz. 

For your setup: Use voltage and current sensors to calculate impedance. 
Example: ACS758LCB-100B-PFF-T (100A Hall effect sensor) for current, and a voltage divider (e.g., 1MΩ and 1kΩ resistors) with an op-amp buffer (e.g., OP07) for voltage.

How the Fully Automatic Tuner Works

Here's how the tuner operates in four key steps:

Step 1: Measuring the Mismatch
The power source sends a small test signal. 
Voltage and current sensors measure how well the power is being transferred to the WFC. 
The microcontroller calculates the mismatch (similar to SWR but adapted for low frequencies).

Step 2: Adjusting the Circuit Automatically
The tuner has inductors and capacitors that can be switched in or out via relays. 
The microcontroller activates different combinations to change the impedance until it matches the power source.

Step 3: Fine-Tuning
After finding a rough match, the microcontroller makes small adjustments to optimize the match. 
It continuously monitors and adjusts to maintain resonance as conditions change (e.g., bubble formation).

Step 4: Saving the Settings (Optional)
Some tuners save settings for future use, but this may not be necessary if the WFC's load is consistent.
Building the Fully Automatic Tuner
Here's how to build the tuner step by step:

Step 1: Design the Impedance Matching Network
Use a switched L-network with multiple inductors and capacitors that can be selected automatically. 
Inductors: 5 inductors (e.g., 100µH, 200µH, 400µH, 800µH, 1.6mH), each rated for 10A. 
Example: Bourns 1140-102K-RC (1mH, 10A).
Capacitors: 5 capacitors (e.g., 0.1µF, 0.2µF, 0.4µF, 0.8µF, 1.6µF), each rated for 1200V. 
Example: Vishay MKP1848C series.

Step 2: Select High-Power Relays
Use relays that can handle 1200V and 10A. 
Mechanical Relays: Omron G7L-2A-TUB (25A at 250V AC; verify DC ratings). 
Solid-State Relays: Crydom D1D40 (40A, 100V DC; use multiple in series for 1200V).

Step 3: Implement the Measurement System
Use sensors to measure voltage and current. 
Current Sensor: ACS758LCB-100B-PFF-T (100A Hall effect sensor). 
Voltage Sensor: A voltage divider (e.g., 1MΩ and 1kΩ resistors) with an op-amp buffer (e.g., OP07).

Step 4: Use a Microcontroller for Automatic Control
The microcontroller reads sensor data, calculates the mismatch, and adjusts the relays. 
Microcontroller: Arduino Uno or STM32 board. 
Software: Write a custom program to implement a tuning algorithm (e.g., simple search or gradient descent).

Step 5: Integrate and Test
Connect the microcontroller to the relays via driver circuits (e.g., ULN2803). 
Test the system at low power first, then scale up to full voltage and current.
Challenges and Considerations

Component Sizing: 
Inductors and capacitors must be large to handle 5 kHz and high power. A 1mH inductor for 10A may be several inches in diameter.

Relay Selection: 
Finding relays for 1200V DC at 10A is difficult. You may need multiple relays in series or solid-state solutions.

Microcontroller Programming: 
Writing the tuning algorithm requires programming knowledge. Basic examples are available online, but customization is needed.

Safety: 
High voltage (1200V) and current (10A) are dangerous. Ensure proper insulation, grounding, and safety measures.
Why This is an Advanced Project

Custom Design Needed:
No off-the-shelf tuner exists for 5 kHz with your power levels, so a custom solution is required.

Expertise Required: 
This project involves high-power electronics, microcontroller programming, and impedance matching theory.

Time and Cost: 
Gathering parts and testing will take time. High-power components can be expensive.
Summary and Advice

How the Tuner Works: 
It automatically adjusts inductors and capacitors using relays, guided by a microcontroller and sensors, to match impedance and minimize reflections.

For Your Specs: 
You need large inductors (100µH–10mH), high-voltage capacitors (0.1µF–10µF, 1200V), high-power relays, and a custom measurement system for 5 kHz.

Parts Suggestions: 
Use components like Bourns inductors, Vishay capacitors, Omron relays, and an Arduino for control.

Advice: 
This is an advanced project. Start with small steps, test at low power,

LINKS to get you started
https://de.aliexpress.com/i/1005003385068518.html?gatewayAdapt=glo2deu

https://buypin.cashperson.top/index.php?main_page=product_info&products_id=1993361

https://de.aliexpress.com/i/1005003385068518.html?gatewayAdapt=glo2deu


PS THIS WAS SAVED BY DAN SECURE SUPPLIES IN 2004
and preserved shared  public since than 11 years latter people finally put tit to use and now we see it accelerating
so it seams open source and saving things does take time but  has huge effect

So We are are adjusting spec to be VLF HVDC 

Converting an automatic antenna tuner (ATU) like the ATU-100 or a similar model such as the MFJ-939 for a specific setup—such as one operating at 5 kHz with 10V to 1200V, 5 to 10A current, and a water capacitor load—requires significant changes. These tuners are originally designed for radio frequencies (1.8–50 MHz) and lower power levels, so adapting them involves understanding their basic operation and modifying their components. Below, I’ll explain how an ATU works, what each part does in the circuit, and the steps to adapt it for your needs. The explanation is broken into titled sections to make it clear and approachable, even if you’re new to electronics.
1. What Does an Automatic Antenna Tuner Do?
An automatic antenna tuner adjusts the electrical "match" between a transmitter and its load (usually an antenna) to ensure maximum power transfer and minimal power loss. It does this by tweaking a combination of inductors and capacitors to balance the impedance (a measure of electrical resistance to alternating current) at a specific frequency.
In Simple Terms: Think of the ATU as a mediator that helps the transmitter and load communicate effectively. For your setup, the load is a water capacitor instead of an antenna, and the frequency is much lower (5 kHz) than what these tuners are built for.
2. Key Parts of an ATU and Their Roles
Here’s a breakdown of the main components in an ATU-100 or MFJ-939 and what they do:
Inductors (L):
These are coils of wire that resist changes in current, providing inductive reactance.
They help balance out capacitive effects in the load.
In the ATU-100, they’re small (e.g., 0.1µH to 6.4µH) because they’re designed for high frequencies.
Capacitors (C):
These store electrical charge and provide capacitive reactance.
They counteract inductive effects in the load.
In the ATU-100, they’re also small (e.g., 10pF to 470pF) for high-frequency use.
Relays:
These are electrically controlled switches that connect or disconnect inductors and capacitors.
They allow the tuner to try different combinations to find the best match.
Microcontroller:
The "brain" of the ATU.
It measures how well the transmitter and load are matched and controls the relays to adjust the circuit.
SWR Bridge:
This measures the Standing Wave Ratio (SWR), which shows how much power is reflected back from the load.
A low SWR (close to 1:1) means a good match.
3. How Does an ATU Work?
Here’s the step-by-step process an ATU like the ATU-100 follows:
Step 1: Detecting a Mismatch
The transmitter sends a small test signal.
The SWR bridge checks how much power is sent forward and how much bounces back.
A high SWR means the impedance doesn’t match.
Step 2: Adjusting the Circuit
The microcontroller uses relays to switch different inductors and capacitors into the circuit.
This changes the impedance the transmitter "sees."
Step 3: Finding the Best Match
The microcontroller tests various combinations, checking the SWR each time.
It picks the one with the lowest SWR.
Step 4: Locking the Settings
Once the best match is found, the tuner keeps those settings for that frequency.
4. Why Your Setup Is Different
Your system—5 kHz frequency, up to 1200V, 5–10A current, and a water capacitor load—doesn’t match what the ATU-100 or MFJ-939 is designed for:
Frequency: These tuners work at 1.8–50 MHz; 5 kHz is much lower.
Power: They handle a few hundred watts, while your setup could reach thousands of watts (1200V × 10A = 12,000W max).
Load: They’re made for antennas, not water capacitors.
5. Steps to Convert an ATU-100 for Your Setup
To make an ATU-100 work for your needs, you’d need to modify its parts. Here’s how:
Step 1: Replace Inductors and Capacitors
Why Change Them?
The original components are too small for 5 kHz and high power.
What to Use:
Inductors: Swap to larger ones, like 100µH to 10mH, rated for 10A (e.g., Bourns 1140-102K-RC, 1mH, 10A).
Capacitors: Use bigger ones, like 0.1µF to 10µF, rated for 1200V (e.g., Vishay MKP1848C series).
Step 2: Upgrade the Relays
Why Change Them?
The built-in relays can’t handle 1200V or 10A.
What to Use:
High-power relays like Omron G7L-2A-TUB (25A at 250V AC) or solid-state relays like Crydom D1D40 (40A, 100V DC; combine for 1200V).
Step 3: Redesign the SWR Bridge
Why Change It?
The SWR bridge is built for higher frequencies and won’t work at 5 kHz.
What to Do:
Replace it with a custom system using a current sensor (e.g., ACS758) and a voltage sensor (e.g., a voltage divider with an op-amp).
Step 4: Update the Microcontroller
Why Change It?
The tuning logic is set for higher frequencies and smaller components.
What to Do:
Rewrite the firmware to use the new sensors and handle larger inductors and capacitors. This requires programming skills.
6. Challenges for a Novice
Modifying an ATU-100 is a big project:
Finding Parts: High-power components can be hard to source and costly.
Electronics Skills: You’ll need to redesign circuits and understand impedance.
Programming: Changing the microcontroller’s code isn’t beginner-friendly.
Safety: 1200V and 10A can be dangerous—insulation and caution are a must.
7. Easier Options for Beginners
If this feels overwhelming, try these instead:
Manual Tuning:
Use a variable inductor and capacitor, adjusting them by hand while watching a meter.
Fixed Circuit:
Calculate the inductor and capacitor values your setup needs at 5 kHz and build a simple circuit.
Get Help:
Ask an experienced electronics hobbyist or engineer to assist.
Summary
An ATU-100 or MFJ-939 uses inductors, capacitors, relays, a microcontroller, and an SWR bridge to match impedance automatically. To adapt it for your 5 kHz, high-power water capacitor setup, you’d replace the components with bigger, stronger ones, redesign the measurement system, and update the programming. For a novice, this is tough, so starting with manual tuning or seeking help might be smarter. Let me know if you’d like more details on any part!

To convert the ATU-100 automatic antenna tuner for operation at 5 kHz, with voltages ranging from 10V to 1200V, currents from 5A to 10A, and a water capacitor load, we need to replace several components to handle the lower frequency, higher voltage, and higher current. Below is the bill of materials (BOM) for this conversion, tailored for clarity and completeness.

Overview of Requirements
Frequency: 5 kHz (much lower than the ATU-100's typical 1.8–50 MHz range).
Voltage Range: 10V to 1200V.
Current Range: 5A to 10A.
Load: Water capacitor, requiring impedance matching at 5 kHz.

Challenges:
Inductors and capacitors need larger values for low-frequency operation.
Components must handle high voltage (1200V) and high current (10A).
The measurement system needs to work at 5 kHz, requiring changes from RF methods.
Firmware will need significant updates, but this BOM focuses on hardware.
Bill of Materials (BOM)

1. Inductors
Purpose: Replace the original inductors (typically 0.1µH to 10µH) with larger values for 5 kHz operation and ensure they can handle 10A.

Reactance Calculation:
At 5 kHz, for a typical impedance of 50 ohms, inductance is calculated as:
XL=2πfL⟹L=XL2πf=502π×5000≈1.59mH
.
To cover various impedance transformations, use a range of inductors from 100µH to 10mH.

Specifications:
Inductance range: 100µH, 200µH, 500µH, 1mH, 2mH, 5mH, 10mH.
Current rating: ≥10A.
Core: Ferrite or powdered iron to prevent saturation at high currents.
Wire: 14 AWG or thicker to handle current.
Quantity: 5 inductors (covering a range of inductance values).

Possible Parts:
Custom-wound inductors using ferrite toroids:
Toroids: Magnetics Inc. 58930A2 (high permeability) or 77083A7 (powdered iron for high current).
Wind with 14 AWG wire, calculate turns for desired inductance.

2. Capacitors
Purpose: Replace the original capacitors (typically pF to nF, rated for a few hundred volts) with higher capacitance values and voltage ratings.

Reactance Calculation:
At 5 kHz, for 50 ohms, capacitance is calculated as:
XC=12πfC⟹C=12πfXC=12π×5000×50≈0.636μF
.
Use a range from 0.1µF to 10µF for flexibility.

Specifications:
Capacitance range: 0.1µF, 0.2µF, 0.5µF, 1µF, 2µF, 5µF, 10µF.
Voltage rating: ≥1200V.
Current rating: Must handle up to 10A.
Type: Film capacitors (preferred for low loss and stability at 5 kHz).
Quantity: 5 capacitors (covering a range of capacitance values).

Possible Parts:
Vishay MKP1848C series (DC-link film capacitors, up to 1200V).
Example: MKP1848612094P4 (12µF, 900V), but verify voltage rating or use multiple in parallel/series.

Note: If 1200V-rated capacitors are unavailable, consider series combinations to increase voltage handling, but this adds complexity.
3. Relays
Purpose: Replace the original relays (typically rated for 2A, low voltage) with high-power relays to switch inductors and capacitors under 1200V and 10A.
Specifications:
Voltage rating: ≥1200V.
Current rating: ≥10A.
Type: Mechanical relays rated for AC switching (since 5 kHz is AC, albeit low frequency).
Switching speed: Not critical, as relays switch infrequently during tuning.
Quantity: 10 relays (5 for inductors, 5 for capacitors).

Possible Parts:
Omron G7L-2A-TUB:
Rated for 25A at 250VAC, but verify DC ratings for 1200V.

Panasonic HEV series:
Rated for 20A at 277VAC, but confirm suitability for 5 kHz and 1200V.
Alternative: Solid-state relays (SSRs) for high-voltage DC:
Crydom D53TP50D (50A, 530V), but may need series combinations for 1200V.
Note: For safety, choose relays with higher voltage ratings or use multiple relays in series, though this adds complexity.

4. Voltage Sensor
Purpose: Measure voltage across the load at 5 kHz, up to 1200V, for impedance calculation.
Method: Use a voltage divider to step down the voltage to a level measurable by the microcontroller's ADC, with buffering for safety.

Specifications:
Voltage divider:
High-voltage resistors to divide 1200V down to ~1.2V.
Example ratio: 10MΩ and 10kΩ (divides by 1000).
Resistor ratings:

10MΩ resistors: ≥1W, 1% tolerance, high-voltage rating.
10kΩ resistor: 0.25W, 1% tolerance.
Buffer: High-voltage op-amp to isolate the microcontroller.
Quantity:
2 × 10MΩ resistors (1W, 1% tolerance).
1 × 10kΩ resistor (0.25W, 1% tolerance).
1 × op-amp (e.g., OPA551, high-voltage capable).

5. Current Sensor
Purpose: Measure current through the load at 5 kHz, up to 10A, for impedance calculation.
Method: Use a Hall effect sensor for isolated current measurement.

Specifications:
Current range: ≥10A (preferably up to 20A for margin).
Output: Analog signal proportional to current, compatible with microcontroller ADC.
Quantity: 1 current sensor.

Possible Parts:
Allegro ACS758LCB-100B-PFF-T:
Bidirectional, ±100A range, suitable for 5–10A.
Alternative: Shunt resistor with amplifier, but Hall effect is safer due to isolation.

6. Microcontroller
Purpose: Control the relays and process voltage/current measurements for impedance matching.
Options:
Original ATU-100 microcontroller (e.g., PIC16F1938), but requires significant firmware changes.
Alternative: Arduino (e.g., Arduino Uno) for easier development.
Recommendation:
Use Arduino Uno for simplicity, especially for novices.
Note: Firmware rewrite is required (beyond the scope of this BOM).
Quantity: 1 microcontroller (Arduino Uno or PIC16F1938).

7. Connectors
Purpose: Provide safe input and output connections for 1200V and 10A.
Specifications:
Voltage rating: ≥1200V.
Current rating: ≥10A.
Type: Banana jacks or screw terminals.
Quantity: 2 sets (input and output).
Possible Parts:
Banana jacks rated for 1200V, 10A (e.g., Pomona 1325 series, verify ratings).
Screw terminals rated for high voltage and current.

8. Miscellaneous Components
Relay Drivers:
Purpose: Drive relay coils if the microcontroller cannot source enough current.
Possible Part: ULN2803 (Darlington transistor array).
Quantity: 2 (each can drive 8 relays, sufficient for 10 relays).

Power Supply:
Purpose: Power the microcontroller and relay coils.
Note: The ATU-100's existing power supply (e.g., 12V) may suffice, assuming proper isolation.
If needed: 12V regulator (e.g., LM7812).
Quantity: 1 (if replacement is necessary).

PCB Considerations:
Note: The original ATU-100 PCB may not handle 10A or 1200V due to trace widths and spacing.
Recommendation: Redesign the PCB with wider traces and larger spacing for safety.
Temporary solution: Modify the existing PCB with external wiring for high-current paths, but redesign is safer.
Additional Notes

Heat Dissipation:
Inductors and relays will generate heat at 10A. Ensure proper heat sinking or ventilation in the enclosure.
Safety:
Working with 1200V is dangerous. Verify all components are properly rated, and use an enclosure that prevents accidental contact.
Ensure proper grounding and insulation.

Calibration:
After assembly, calibrate the system to map relay settings to impedance transformations.

Firmware:
The firmware must be rewritten to handle the new measurement system and component values. This requires embedded programming knowledge (e.g., C for PIC or Arduino).

Part Availability:
Specific part numbers are suggestions. Adjust based on availability and exact requirements.

Summary of BOM
Component
Specifications
Quantity
Possible Parts
Inductors
100µH–10mH, ≥10A, ferrite/powdered iron core
5
Custom-wound on Magnetics Inc. toroids (e.g., 58930A2, 77083A7), 14 AWG wire
Capacitors
0.1µF–10µF, ≥1200V, film type
5
Vishay MKP1848C series (e.g., MKP1848612094P4, verify voltage rating)
Relays
≥1200V, ≥10A, AC switching
10
Omron G7L-2A-TUB, Panasonic HEV series, or Crydom D53TP50D (SSRs, verify rating)
Voltage Sensor
Voltage divider + op-amp
-
2 × 10MΩ (1W), 1 × 10kΩ (0.25W) resistors, OPA551 op-amp
Current Sensor
≥10A, Hall effect, analog output
1
Allegro ACS758LCB-100B-PFF-T
Microcontroller
Original PIC or Arduino
1
Arduino Uno or PIC16F1938 (requires firmware rewrite)
Connectors
Banana jacks or screw terminals, ≥1200V, ≥10A
2 sets
Pomona 1325 series or equivalent
Relay Drivers
Darlington array for relay coils
2
ULN2803
Power Supply (optional)
12V regulator for microcontroller/relays
1 (if needed)
LM7812 (if replacement is necessary)
This BOM provides the components needed for the ATU-100 conversion, ensuring compatibility with 5 kHz operation, 10V–1200V, 5–10A, and a water capacitor load. Note that this is a complex project requiring careful attention to safety and calibration.

This, combined with the VNA content you posted makes a ton of sense, I have some learning to do around both but the knowledge will really leap forward the trickiest part: the coils. Although I am just skimming at the moment, I see the intent. Thanks for sharing.

 Your Welcome

Also a Very Important note is forget using digital van us only Analogue  duel needle  tuner for antenna to seen reflection and
than  once you understand that and see the  balance or resonance than at the  vlt auto tuner

However, standard LCR meters may not handle the high voltage and current you specified, as they are typically for low-power component testing. For power measurement, consider a power analyzer like the

Keysight PA2203A with a 2.5 MHz bandwidth (AC Power Analyzers | Keysight), but verify it can manage up to 12 kW (calculated from 1200V * 10A).

5 kHz with 10V to 1200V, 5 to 10A current, and a water capacitor load in replace of a Antenna

Conclusion and Recommendations
No off-the-shelf SWR/wattmeter like the MFJ-849 or similar meets the user's requirements for 5 kHz with 10V to 1200V and 5A to 10A. At 5 kHz, SWR measurements are likely not applicable in standard setups due to the long wavelength, suggesting a focus on impedance and power measurement

=============================
Measuring Power Reflection
For power reflection, similar to an antenna setup, the PA2203A doesn’t directly measure forward and reflected power like an SWR/wattmeter. However, you can estimate it by:
Measuring the load impedance (Z_load) using the PA2203A’s voltage and current measurements, including phase difference.

Knowing the source impedance (Z_source), if available.

Calculating the reflection coefficient (Γ = (Z_load - Z_source) / (Z_load + Z_source)) and then the reflected power as P_reflected = P_forward * |Γ|^2, where P_forward is the source power.

This process is more complex and requires additional calculations, unlike the direct readings from an SWR/wattmeter.
Practical Tips
Ensure you use a 10:1 voltage probe for 1200V and select the 50A current range. Safety is crucial with high voltages, so follow appropriate protocols. For more details, check the IntegraVision PA2200 Series Power Analyzers Data Sheet.




Key Points
Research suggests the Keysight PA2203A can likely measure at 5 kHz with voltages up to 1200V using a 10:1 probe, and currents up to 10A with its 50A internal shunt, handling up to 12 kW.
It is different from an oscilloscope, offering specialized power measurement capabilities

Research suggests the Keysight PA2203A can measure power output to a water capacitor but cannot directly measure power reflection like an SWR/wattmeter for an antenna.

It seems likely that users can calculate reflected power by measuring load impedance and knowing source impedance, but this requires additional steps.

The evidence leans toward the PA2203A being suitable for active and reactive power measurements, not RF-specific reflected power.

When the Reflection ratio  is  under 2 or 0 to 1.5 cell is in resonance

i post this here i have some part selected and will post a better doc in day or so to guide on this
this will apply to Meyer and Donate Smith Gerad Morin and Nikola tesla

search ou this doc MFJCatalog2023 .pdf https://mfjenterprises.com/

https://youtu.be/RRkbdTadmUU?si=8vrfCMg2zd1-cV0V

SWR / Reflection
this will help  one might  modify this to suit spec,
5 kHz with 10V to 1200V, 5 to 10A current, and a water capacitor load in replace of a Antenna

https://youtu.be/GrqGrWyb4Xc?si=rZ4R2HefAxtWvGeW
 

Below is a detailed list of upgrades required to modify the MFJ-901B antenna tuner to operate at 5 kHz with voltages ranging from 10V to 1200V and currents from 5A to 10A. The MFJ-901B is originally designed for HF bands (1.8-30 MHz) and a maximum power of 200W, so significant changes are needed to accommodate the lower frequency and higher voltage and current specifications.



============================================
=List of Upgrades
Replace Variable Capacitors with a Switched Bank of High-Voltage, High-Capacitance Capacitors
Why: The stock variable capacitors (typically 10-500 pF) are designed for HF frequencies and cannot provide the capacitance needed for impedance matching or resonance at 5 kHz, where values in the microfarad (μF) range (e.g., 1 μF to 100 μF) may be required. Additionally, they are unlikely to handle 1200V.

How:
Remove the existing air variable capacitors.

Install a bank of fixed capacitors rated for at least 1200V and capable of handling currents up to 10A or more, depending on the network configuration.

Use capacitance values such as 1 μF, 2 μF, 4 μF, etc., up to 100 μF, to allow flexibility in matching.

Connect these capacitors to high-current, high-voltage switches to select different values or combinations, as variable capacitors in the μF range are not commonly available.

Components: High-voltage film or ceramic capacitors (e.g., 1200V or higher rating).

Replace the Roller Inductor with a Switched Set of High-Current, High-Inductance Inductors
Why: The stock roller inductor (typically up to 20 μH) is suited for HF and cannot provide the inductance needed at 5 kHz (e.g., 100 μH to 10 mH) or handle currents up to 10A without saturating or overheating.

How:
Remove the existing roller inductor.

Install a set of fixed inductors with inductance values ranging from 100 μH to 10 mH, designed for low-frequency operation (5 kHz).

Ensure each inductor can handle 10A without saturation, using thick wire (e.g., 10 AWG) and appropriate core materials (e.g., iron powder or ferrite optimized for VLF).

Use high-current switches to select different inductance values or combinations for adjustability.

Components: Custom-wound inductors with suitable cores for 5 kHz and 10A current capacity.

Upgrade All Internal Wiring to Handle 10A
Why: The stock wiring is designed for approximately 2A (based on 200W at 50 ohms), which is insufficient for 10A.

How:
Replace all internal wiring with thick copper wire, at least 10 AWG, to safely carry 10A without excessive resistance or heating.

Reinforce all connections (e.g., solder joints, terminals) to handle the increased current.

Components: 10 AWG or 8 AWG copper wire rated for 10A or higher.

Replace Switches with High-Power, High-Voltage Switches
Why: The stock rotary switches are not rated for 1200V or 10A and may fail under the new operating conditions.

How:
Remove existing switches used for configuration or component selection.

Install switches rated for at least 1200V and 10A, ensuring proper insulation to prevent arcing.

Components: High-power rotary or toggle switches designed for high voltage and current.

Modify or Expand the Enclosure to Fit Larger Components
Why: The stock MFJ-901B enclosure is compact and may not accommodate the larger capacitors and inductors required.

How:
Assess the space needed for the new components.

If insufficient, replace the enclosure with a larger one or mount some components (e.g., capacitors or inductors) externally.

Ensure the new setup maintains insulation and safety for high-voltage operation.

Components: Larger metal or insulated enclosure with adequate space.

Additional Notes
Tuning and Matching: At 5 kHz, traditional SWR meters may not work due to the low frequency. To tune the modified tuner, measure voltage and current at the input to calculate impedance, or use a vector network analyzer capable of operating at 5 kHz. Adjust the capacitors and inductors to minimize reflections and maximize power transfer to the load.

Safety: With 1200V and 10A, ensure all components are insulated, and follow high-voltage safety practices during modification and use.

Heat Management: High currents may generate heat in the inductors and wiring. Consider adding heat sinks or cooling (e.g., a fan) if necessary.

Summary
These upgrades transform the MFJ-901B into a tuner capable of operating at 5 kHz with voltages from 10V to 1200V and currents from 5A to 10A:
Capacitors: Switched bank of high-voltage (≥1200V), high-capacitance (1 μF to 100 μF) units.

Inductors: Switched set of high-current (≥10A), high-inductance (100 μH to 10 mH) units.

Wiring: Thick copper wire (≥10 AWG).

Switches: High-power units rated for 1200V and 10A.

Enclosure: Expanded or modified as needed.

This overhaul is extensive, and building a custom matching network might be an alternative. However, these steps allow the MFJ-901B to be adapted for your specific requirements.

For HF Modifications: The MFJ-849 Digital SWR/Wattmeter is best suited for a modified MFJ-901B staying within 1.8–525 MHz and up to 200W. It’s precise, user-friendly, and matches the tuner’s typical use. If the modification boosts power beyond 200W, the MFJ-826B (up to 1500W) or MFJ-874 (up to 2000W) is better.

For 5 kHz Modification: No MFJ SWR/watt meter directly supports 5 kHz. The MFJ-259D can approximate SWR at 5 kHz (with reduced accuracy below 100 kHz), but you’ll need a separate low-frequency wattmeter or manual voltage/current measurements for power and reflection. Alternatively, a custom directional coupler or a non-MFJ instrument like a VNA for 5 kHz could be considered.

Final Answer: Without modification specifics, the MFJ-849 is the best general choice for HF use. If modified for 5 kHz, use the MFJ-259D with a separate power measurement method, as no single MFJ meter fully satisfies the requirement.

Requirements for the Meter
The meter must measure:
SWR (Standing Wave Ratio): To assess impedance matching.

Power: Forward and reflected power to calculate efficiency and reflection.

Reflection: Directly or via power measurements.

It must also match the frequency and power range of the modified MFJ-901B.

MFJ Meter Options
MFJ offers various SWR/watt meters, but most are designed for amateur radio frequencies (1.8 MHz and up). Let’s explore the best candidates:
1. MFJ-849 Digital SWR/Wattmeter
Frequency Range: 1.8–525 MHz

Power Range: Up to 200W

Features: Digital display, measures SWR, forward, and reflected power.

Suitability: Ideal for an unmodified MFJ-901B or one modified to stay within HF bands and 200W. However, it won’t work at 5 kHz.

2. MFJ-826B Digital SWR/Wattmeter
Frequency Range: 1.8–54 MHz

Power Range: Up to 1500W

Features: Digital, measures SWR, power, and includes frequency counter.

Suitability: Fits if the modification increases power capacity (e.g., up to 1500W) but stays in HF. Not usable at 5 kHz.

3. MFJ-874 GrandMaster SWR/Wattmeter
Frequency Range: 1.8–525 MHz

Power Range: Up to 2000W

Features: Analog, measures SWR and power.

Suitability: Good for higher power modifications within HF. Ineffective at 5 kHz.

4. MFJ-259D Antenna Analyzer
Frequency Range: 100 kHz–230 MHz

Power Range: Not a wattmeter; measures SWR and impedance.

Features: Portable, analyzes SWR and impedance but lacks direct power measurement.

Suitability: Closest to 5 kHz (down to 100 kHz), but not specified for 5 kHz, and not a power meter.

Analysis Based on Modification Scenarios
Scenario 1: HF Modification (1.8–30 MHz)
Assumption: Modification keeps the tuner in HF with possibly higher power.

Best Choice:
MFJ-849 for up to 200W (matches stock MFJ-901B).

MFJ-826B or MFJ-874 if power exceeds 200W (up to 1500W or 2000W).

Reason: These meters cover HF, measure SWR, power, and reflection, and integrate well with a tuner.

Scenario 2: Low-Frequency Modification (e.g., 5 kHz)
Assumption: Modified for 5 kHz with high power (e.g., 12 kW from 1200V * 10A).

Challenge: No standard MFJ SWR/watt meter operates at 5 kHz; most start at 1.8 MHz. The MFJ-259D reaches 100 kHz but isn’t specified for 5 kHz and lacks power measurement.

Best Option:
MFJ-259D for SWR and impedance (with reduced accuracy at 5 kHz).

Supplement with a separate low-frequency wattmeter for power.

Reason: No single MFJ product fully meets the need at 5 kHz.

To determine the best analogue meter that suits most needs, we need to consider what makes an analogue meter effective and versatile for general use. Analogue meters are devices that use a needle or pointer to display measurements on a scale, unlike digital meters that show numerical values on a screen. They are commonly used for electrical measurements such as voltage, current, and resistance, and are valued for their ability to show trends over time, durability, and lack of need for batteries.
Since your query doesn’t specify a particular application, I’ll assume you’re looking for a general-purpose analogue meter, likely a multimeter, which can handle a variety of electrical measurements. Here’s how we can approach finding the best one:
Key Factors to Consider
Measurement Capabilities: The meter should measure AC and DC voltage, current, and resistance across a wide range to suit most setups.

Accuracy: Analogue meters typically have an accuracy of 2-3% of full scale, but higher accuracy is preferable for reliable readings.

Ease of Use: A clear, readable scale reduces errors like parallax, where the needle’s position appears different depending on the viewing angle.

Durability: A robust build ensures the meter lasts in various conditions.

Versatility: A general-purpose meter should work for most common electrical tasks without needing specialized features.

Evaluating Options
Several well-regarded analogue multimeters stand out for general use:
Simpson 260 Series 
Pros: A classic, widely respected meter with a long history of reliability. It measures AC/DC voltage (up to 1000V), current (up to 10A), and resistance (up to 20MΩ). Accuracy is 2% for DC and 3% for AC, with a large, mirrored scale to minimize reading errors. It’s durable and repairable, making it ideal for fieldwork or educational settings. 

Cons: Slightly lower accuracy compared to some alternatives.

Sanwa EM7000 
Pros: A modern Japanese-made multimeter with 1.5% DC accuracy and 2.5% AC accuracy—better than many analogues. It measures up to 1000V AC/DC and has a frequency response up to 100 kHz for AC, plus high input impedance for sensitive circuits. It features a mirrored scale and a compact, professional design. 

Cons: May be less available in some regions compared to the Simpson.

AVO 8 
Pros: A vintage British meter known for precision, offering 1% DC accuracy and 2.5% AC accuracy—among the best for analogue multimeters. It measures up to 2500V DC and 3000V AC, with resistance up to 200MΩ. Its sensitive 50μA movement and large, clear scale enhance readability, and its sturdy bakelite case ensures longevity. 

Cons: Larger and heavier, better suited for bench use than portability. As a vintage model, it may be harder to find or repair.

Decision
For a meter that “best suits” most setups, accuracy, versatility, and reliability are critical. The AVO 8 stands out with its exceptional 1% DC accuracy, making it highly precise for an analogue meter. Its wide measurement range and robust construction make it suitable for most electrical tasks, from hobbyist projects to professional bench work. While it’s less portable and potentially harder to source, its performance outweighs these drawbacks for general-purpose use. The Simpson 260 excels in durability and availability, and the Sanwa EM7000 offers modern features, but the AVO 8’s superior accuracy tips the scale when the goal is the “best” overall.
Final Recommendation
The AVO 8 is the best analogue meter for most setups due to its high accuracy, broad measurement capabilities, and proven reliability, making it an excellent choice for a wide range of electrical applications.

To modify the MFJ-849 Digital SWR/Wattmeter for operation at 5 kHz with voltages ranging from 10V to 1200V and currents from 5A to 10A, you’ll need to adjust its input stage, upgrade components for higher power, and add external scaling circuits. The stock MFJ-849 is designed for 1.8–525 MHz and up to 200W (about 100V and 2A in a 50-ohm system), so significant changes are required. Below are the step-by-step modifications:
Step 1: Modify the Input Coupling for Low-Frequency Operation
Purpose: Ensure the meter can process 5 kHz signals, which are much lower than its designed range of 1.8 MHz and up.

Why It’s Needed: The input stage likely includes coupling capacitors that block or attenuate low frequencies like 5 kHz.

How to Do It:
Open the MFJ-849 and locate the input coupling capacitors (typically small ceramic or film capacitors, e.g., 0.01 μF) connected to the RF input.

Calculate the current reactance: For a 0.01 μF capacitor at 5 kHz, reactance is ~3 kΩ, which is too high for accurate measurement.

Replace these capacitors with a larger value, such as 10 μF, reducing reactance to ~3 Ω at 5 kHz, allowing the signal to pass effectively.

Ensure the new capacitors are rated for at least 1200V to handle the maximum voltage.

Components Needed:
10 μF capacitors, 1200V or higher rating (e.g., electrolytic or high-voltage film capacitors).

Step 2: Upgrade Power-Handling Components
Purpose: Enable the meter to handle higher voltages (up to 1200V) and currents (up to 10A), far exceeding its 200W rating.

Why It’s Needed: Internal components like resistors and diodes are not rated for such high power levels.

How to Do It:
Identify resistors in the power-sensing path (likely low-wattage, e.g., 1/4W or 1/2W). Replace them with 5W or 10W resistors to handle increased power dissipation.

Check diodes in the rectification circuit (used to convert RF to DC for measurement). Replace them with diodes rated for 1200V and sufficient current (e.g., 10A ultrafast diodes).

Upgrade wiring and connectors between the input and sensing circuitry with thicker wire (e.g., 10 AWG) to carry up to 10A without overheating.

Components Needed:
High-power resistors (e.g., 5W or 10W, same resistance values as originals).

High-voltage diodes (e.g., 1200V, 10A rating).

10 AWG copper wire.

Step 3: Add an External Voltage Divider for High-Voltage Measurement
Purpose: Scale down the input voltage to a level the MFJ-849 can safely measure.

Why It’s Needed: The meter’s internal circuitry is designed for ~100V max, not 1200V.

How to Do It:
Build a 10:1 voltage divider using two resistors:
R1 = 9 MΩ (high-side resistor).

R2 = 1 MΩ (low-side resistor to ground).

This reduces 1200V to 120V, within the meter’s range.

Connect the divider across the input terminals, feeding the scaled output (across R2) to the MFJ-849’s input.

Use resistors rated for 1200V and sufficient power (e.g., 5W) to handle dissipation.

Note: You’ll multiply the displayed voltage or power readings by 10 or 100 (respectively) to account for the scaling.

Components Needed:
9 MΩ and 1 MΩ resistors, 1200V rating, 5W or higher (e.g., precision metal film resistors).

Step 4: Add an External Current Transformer for High-Current Measurement
Purpose: Reduce the input current to a level the meter can handle.

Why It’s Needed: The MFJ-849 is not designed for 10A; its internal sensing is likely limited to ~2A.

How to Do It:
Install a 10:1 current transformer (CT) on the input line:
Primary winding: Pass the 5A–10A current through it.

Secondary winding: Outputs 0.5A–1A, suitable for the meter.

Ensure the CT is rated for 5 kHz operation (e.g., an audio-frequency transformer).

Connect the secondary output to the MFJ-849’s current-sensing input (after the modified coupling capacitor).

Power scales with the square of the current ratio (10² = 100), so multiply the meter’s power reading by 100 to get the true value.

Components Needed:
10:1 current transformer, rated for 5 kHz and 10A primary current.

Step 5: Calibrate Power Measurement for 5 kHz
Purpose: Ensure accurate power readings at 5 kHz.

Why It’s Needed: The meter’s calibration is optimized for higher frequencies, and the modified input may alter its response.

How to Do It:
Set up a test circuit with a known power source at 5 kHz (e.g., a signal generator with a 50-ohm load delivering 100W).

Measure the output with the modified MFJ-849 and compare it to the known value.

If adjustable trim pots exist in the analog circuitry, tweak them until the reading matches the known power (after accounting for the 100x scaling from the divider and CT).

If no trim pots are available (common in digital meters), note the error and apply a manual correction factor to future readings.

Note: Firmware-based calibration isn’t user-accessible, so manual correction may be necessary.

Step 6: Address SWR Measurement Limitations
Purpose: Clarify that SWR cannot be accurately measured at 5 kHz with this setup.

Why It’s Needed: The MFJ-849’s directional coupler is designed for RF frequencies (1.8–525 MHz), not 5 kHz, where wavelength (~60 km) makes SWR less meaningful in short setups.

How to Handle It:
Use the meter for power measurement only, accepting that SWR readings will be unreliable.

For impedance matching or reflection analysis, use external tools:
An oscilloscope to monitor voltage and current waveforms and adjust for maximum power transfer.

A low-frequency impedance bridge (e.g., Wheatstone bridge) to measure load impedance directly.

Note: Building a custom 5 kHz directional coupler is possible but complex and unlikely to integrate seamlessly with the MFJ-849.

Summary of Modifications
Input Stage: Replace coupling capacitors with 10 μF, 1200V-rated ones.

Power Components: Upgrade resistors, diodes, and wiring for 1200V and 10A.

Voltage Scaling: Add a 10:1 voltage divider (9 MΩ and 1 MΩ).

Current Scaling: Add a 10:1 current transformer for 5 kHz.

Calibration: Adjust or manually correct power readings at 5 kHz.

SWR: Rely on external methods instead of the meter.

Final Notes
After these modifications, the MFJ-849 can measure power at 5 kHz across your voltage (10V–1200V) and current (5A–10A) ranges, with readings scaled up by 100 (due to the 10:1 voltage and current reductions). However, SWR measurement will not be accurate due to the meter’s design limitations at 5 kHz. For a fully accurate solution, consider a custom-built meter or benchtop equipment designed for low frequencies and high power.

https://youtu.be/pdOEiML2XGk?si=wozyI-5CyarcnwDA look t meter how is works in this video this is a digital one can use analogue also ,  for auto tune we ned VLF  and atu auto tuner but modified for vlf   but manual is fine  it is a skil to know it show why stan and Stephen draw the schemtics the way they did also not we can document the voltage frequency and the  induction and the 2 caps setting for the voltage levels which is no doubt what they did to stay in resonance at various voltage level thus the selector switch is inductor

To modify your AVO 8 analogue meter to function as an SWR/wattmeter operating at 5 kHz, with voltage ranges from 10V to 1200V and current ranges from 5A to 10A, you’ll need to add an external circuit to process the signals and adapt the meter to display the measurements. The AVO 8 is an excellent multimeter capable of measuring voltages up to 3000V AC and currents up to 10A AC, which covers your specified ranges. However, it isn’t designed to measure standing wave ratio (SWR) or power directly, so we’ll need to create a setup that converts forward and reflected power into DC voltages that the AVO 8 can measure. Below are the step-by-step modifications:
Step 1: Design and Build an External Sensing Circuit
You’ll need an external box that senses the voltage and current in your system, processes them to separate forward and reflected components, and outputs DC voltages for the AVO 8 to read. Here’s how to build it:
Voltage Sensing:
Use a voltage divider to scale down the input voltage (up to 1200V) to a manageable level. For example, to reduce 1200V to 12V (a 100:1 ratio), use two resistors:
R1 = 10 MΩ (high voltage rated)

R2 = 100 kΩ

This gives an output voltage of V_out = V_in × (R2 / (R1 + R2)) ≈ V_in / 100. Ensure the resistors can handle the voltage (use multiple resistors in series if needed for safety) and have sufficient power ratings.

Current Sensing:
Use a current transformer to measure currents from 5A to 10A without significant power loss. Choose a transformer with a 100:1 turns ratio, so 10A in the primary produces 0.1A in the secondary.

Connect a burden resistor (e.g., 10 Ω) across the secondary to convert the current to a voltage. For 10A primary current, secondary current is 0.1A, producing V_i = 0.1A × 10 Ω = 1V.

Signal Processing:
Combine the voltage (V_v from the divider) and current (V_i from the transformer) signals to compute forward and reflected components. Assuming a characteristic impedance Z0 (e.g., 50 Ω):
Forward signal: V_f = V_v + k × V_i

Reflected signal: V_r = V_v - k × V_i

Here, k is a scaling factor adjusted so that when the load matches Z0, V_r is zero. Use operational amplifiers (e.g., OP07) to perform the addition and subtraction. Adjust k by setting the gain of the op-amp handling V_i, where k ≈ Z0 × (scaling factors from your divider and transformer).

Rectification and Filtering:
Feed V_f and V_r into precision rectifiers (built with op-amps and diodes) to convert the 5 kHz AC signals to DC voltages proportional to their magnitudes (|V_f| and |V_r|).

Add low-pass filters to smooth the DC outputs. For a 5 kHz signal (10 kHz after full-wave rectification), use a cutoff frequency of about 10 Hz. With a 10 kΩ resistor, use a capacitor C ≈ 2.2 μF (calculated as 1 / (2π × 10 × 10k)).

Output Selection:
Install a toggle switch to select between the rectified forward voltage (V_f_dc) and reflected voltage (V_r_dc) outputs. This allows you to measure one at a time with the single AVO 8 meter.

Power Supply:
Since the AVO 8 doesn’t provide power, include a separate power source for the op-amps (e.g., ±15V from batteries or a DC adapter).

Safety and Construction:
Use high-voltage-rated components for the voltage divider and ensure the current transformer is suitable for 5 kHz and 10A.

House the circuit in a shielded metal enclosure to reduce noise, with proper grounding and insulated connectors for safety at 1200V.

Step 2: Connect the Circuit to the AVO 8
Connect the output of the toggle switch (either V_f_dc or V_r_dc) to the AVO 8’s DC voltage input terminals.

Set the AVO 8 to an appropriate DC voltage range (e.g., 10V or 100V, depending on your circuit’s output levels). The meter will display the DC voltage corresponding to the selected signal.

Step 3: Calibrate the System
With a Matched Load:
Connect a load equal to the characteristic impedance Z0 (e.g., a 50 Ω resistor). Adjust the op-amp gains (using trimmer resistors) so that V_r_dc reads zero or near zero, confirming the reflected power is minimized.

With Known Power:
Apply a known input power (e.g., 1000W, verifiable with a reference meter). Adjust the overall scaling so that V_f_dc reads a convenient value on the AVO 8 (e.g., 10V for 1000W). Note the scaling factor (e.g., 1V = 100W).

Verify across the range (10V to 1200V, 5A to 10A) to ensure accuracy.

Step 4: Use the Modified AVO 8 to Measure SWR and Power
Measure Forward Power:
Switch to V_f_dc, read the DC voltage on the AVO 8 (e.g., 5V).

Since power is proportional to voltage squared (P = V^2 / Z0), calculate P_forward = (V_f_dc / scaling_factor)^2 × constant. For example, if 10V = 1000W and Z0 = 50 Ω, adjust the constant based on calibration.

Measure Reflected Power:
Switch to V_r_dc, read the voltage (e.g., 1V), and compute P_reflected similarly.

Calculate SWR:
Compute the reflection coefficient |Γ| = V_r_dc / V_f_dc (e.g., 1V / 5V = 0.2).

Then, SWR = (1 + |Γ|) / (1 - |Γ|) = (1 + 0.2) / (1 - 0.2) = 1.2 / 0.8 = 1.5.

Alternatively, create a lookup table or chart to convert meter readings to power and SWR based on your calibration.

Additional Notes
Interpretation: The AVO 8’s linear scale means the DC voltage is proportional to the RMS voltage of the forward or reflected wave, not power directly. You’ll need to square the reading and apply your calibration factor to get power, or use the ratio directly for SWR.

Precision: Use 1% tolerance resistors and precision op-amps for accuracy matching the AVO 8’s quality.

Frequency Response: The AVO 8’s AC response extends to 100 kHz, so 5 kHz is well within its capability, but rectifying to DC avoids needle oscillation and simplifies readings.

By following these steps, your AVO 8 will effectively serve as an SWR/wattmeter at 5 kHz, leveraging its robust measurement capabilities with the aid of an external sensing circuit.

Detailed Reasoning
Key Factors Considered
Measurement Range: Ability to handle a variety of voltages, currents, and resistances.

Accuracy: Precision in DC and AC measurements.

Versatility: Suitability for diverse electrical tasks, including potential moderate-frequency applications.

Durability: Longevity and reliability for consistent use.

Ease of Use: Readability and design features like mirrored scales.

1. AVO 8 – Best Choice
Pros:
Exceptional Accuracy: Offers 1% DC accuracy and 2.5% AC accuracy, making it the most precise of the three. This is ideal for detailed electrical work requiring high reliability.

Wide Measurement Range: Measures up to 2500V DC and 3000V AC, plus resistance up to 200MΩ, covering a broad scope of applications—far exceeding the 1000V limit of the others.

Sensitive Movement: A 50μA movement paired with a large, clear scale enhances readability, reducing errors in measurement.

Durability: Housed in a sturdy bakelite case, it’s built to last, even under demanding conditions.

Versatility: Its frequency response (typically up to 100 kHz) suggests it can handle moderate frequencies, which may align with your "induction etc." reference if it implies AC measurements beyond basic 50/60 Hz.

Cons:
Larger and heavier, making it less portable—better for bench use than fieldwork.

As a vintage model, availability and repairs might be challenging.

Why It’s Best: The AVO 8’s superior accuracy, extensive range, and robust construction make it the top pick for general-purpose use and specialized applications requiring precision and high voltage/current capabilities.

so we need a swr meter for antenna  watts out and reflection back
and we need a 3  know antenner tuner it can have a swr meter if it is modified for range which may reduce need for the  swr watt meter as it will show dx out and reflection to some degree,   

 What are we doing we are measuring the power out to water fuel cell and the reflection back
and we are than adjusted the standing wave rations  to 0 to 1.5  to ensure maximum voltage to water nano bubble  fuel cell dbd voltage zone

Dan

Things I think  are important staff of multi meters for this
type of thinking
stay off of messing with  coils and pwm and switch pulse rates   this swr tuning is after chokes  before blockign diode and can tune resonance  after the fact

https://mfjenterprises.com/products/mfj-23?srsltid=AfmBOopPZvjSvzW5wGmZNOGuFlVWcK1U_nZ29pb1OtwIjyAptyWxyUn8

MFJ-23, BUTTERFLY LOOP AIR VAR CAP, 18-136 PF, 1.5KV, 23

 MODIFY

Notes

VLF ATU

Challenge for those  who can build modify and adapt to be
5 khz  1300 vdc 10 oHm 10 amps automatic


Let’s dive into analyzing the UKRAA VLF Aerial Tuning Unit (ATU) based on the provided manual and address your questions systematically. I’ll incorporate your additional specification of a 10-ohm antenna into the analysis, assuming this refers to the antenna’s impedance or resistance in the circuit context. Since I’m limited to the manual and my knowledge without external searches, I’ll provide detailed answers and flag where assumptions are made.

1. Is this an automatic ATU?
No, the UKRAA VLF ATU is not automatic. It’s a manual tuning unit. The tuning process (Page 8) involves:
Manually rotating a 16-position hex switch to set coarse capacitance.

Adjusting four DIP switches to add capacitance.

Turning a variable tuning capacitor knob (15–150 pF) for fine-tuning.

Monitoring signal strength (e.g., via a VLF receiver or oscilloscope) and adjusting until the maximum amplitude is achieved.

An automatic ATU would use sensors and actuators (e.g., relays or motors) controlled by a microcontroller to adjust tuning without user input—this unit requires hands-on operation.

2. Can it tune to 5 kHz?
The ATU is designed to tune a VLF loop aerial in the 15–35 kHz range (Page 4) with a capacitance range of 50–3500 pF (Appendix 1, Page 10). You’ve specified a “10-ohm antenna,” which I’ll interpret as the antenna’s resistance (possibly DC resistance or an approximation of impedance at VLF). However, for tuning, we need the antenna’s inductance (( L )), as it forms a parallel LC circuit with the ATU’s capacitance.
The resonant frequency is:
f=12πLCf = \frac{1}{2\pi \sqrt{L C}}f = \frac{1}{2\pi \sqrt{L C}}

Where:
( f ) = frequency (5 kHz = 5000 Hz),

( L ) = inductance (in henries),

( C ) = capacitance (50–3500 pF).

The manual doesn’t specify the UKRAA VLF Aerial’s inductance, but we can estimate it based on the 15–35 kHz range:
At 15 kHz with 3500 pF (3.5×10−9 F3.5 \times 10^{-9} \, \text{F}3.5 \times 10^{-9} \, \text{F}
):
L=1(2π⋅15000)2⋅3.5×10−9≈32 mHL = \frac{1}{(2\pi \cdot 15000)^2 \cdot 3.5 \times 10^{-9}} \approx 32 \, \text{mH}L = \frac{1}{(2\pi \cdot 15000)^2 \cdot 3.5 \times 10^{-9}} \approx 32 \, \text{mH}

At 35 kHz with 50 pF (5×10−11 F5 \times 10^{-11} \, \text{F}5 \times 10^{-11} \, \text{F}
):
L=1(2π⋅35000)2⋅5×10−11≈41 mHL = \frac{1}{(2\pi \cdot 35000)^2 \cdot 5 \times 10^{-11}} \approx 41 \, \text{mH}L = \frac{1}{(2\pi \cdot 35000)^2 \cdot 5 \times 10^{-11}} \approx 41 \, \text{mH}

This suggests ( L ) is around 30–40 mH (millihenries, not henries—my earlier response had a unit error). For 5 kHz:
With 3500 pF:
L=1(2π⋅5000)2⋅3.5×10−9≈289 mHL = \frac{1}{(2\pi \cdot 5000)^2 \cdot 3.5 \times 10^{-9}} \approx 289 \, \text{mH}L = \frac{1}{(2\pi \cdot 5000)^2 \cdot 3.5 \times 10^{-9}} \approx 289 \, \text{mH}

With 50 pF:
L=1(2π⋅5000)2⋅5×10−11≈20,253 mH=20.25 HL = \frac{1}{(2\pi \cdot 5000)^2 \cdot 5 \times 10^{-11}} \approx 20,253 \, \text{mH} = 20.25 \, \text{H}L = \frac{1}{(2\pi \cdot 5000)^2 \cdot 5 \times 10^{-11}} \approx 20,253 \, \text{mH} = 20.25 \, \text{H}

If the antenna has L=30–40 mHL = 30–40 \, \text{mH}L = 30–40 \, \text{mH}
, the required capacitance for 5 kHz is:
C=1(2π⋅5000)2⋅0.03≈33,770 pF (33.8 nF)C = \frac{1}{(2\pi \cdot 5000)^2 \cdot 0.03} \approx 33,770 \, \text{pF} \, (33.8 \, \text{nF})C = \frac{1}{(2\pi \cdot 5000)^2 \cdot 0.03} \approx 33,770 \, \text{pF} \, (33.8 \, \text{nF})

The ATU’s max (3500 pF) is too low. It can’t tune to 5 kHz with the stock aerial unless:
The antenna’s inductance is much higher (e.g., 289 mH), or

You add external capacitance (e.g., 30,000 pF in parallel).

The 10-ohm resistance doesn’t directly affect tuning frequency but impacts circuit Q-factor and losses, which I’ll address later.
3. Can it handle 1200 VDC? If not, what voltage?
The ATU is a passive device (Page 4) for receiving VLF signals, not transmitting. It uses capacitors, switches, and a PCB, with no power supply. Voltage tolerance depends on component ratings:
Capacitors: Likely ceramic or film, rated 50–500 VDC in low-power receiving applications.

Variable Capacitor: 15–150 pF, possibly air or mica, typically 200–500 VDC.

Switches: DIP and hex switches are usually 24–100 VDC rated.

PCB: Standard FR4 with ~0.5 mm trace spacing suggests <500 VDC tolerance (per IPC-2221).

In a receiving role, it sees low RF voltages (e.g., <50 V peak). It cannot handle 1200 VDC—the likely limit is 200–500 VDC, based on typical component specs. For 1200 VDC, you’re likely considering a transmitter application, which this isn’t designed for.
4. Can it handle 10 amps? If not, what amps?
As a receiving device, the ATU handles tiny currents (microamps to milliamps) from the aerial to the receiver:
Capacitors: Don’t carry DC current in a tuned circuit; RF current is minimal.

Switches: DIP switches typically handle 100–500 mA.

PCB Traces: 1 mm wide, 1 oz/ft² copper traces carry ~1–2 A max.

BNC Connector: RG59-rated BNC handles <<1 A.

It cannot handle 10 amps—the limit is likely <0.5 A, constrained by switches and traces. In practice, it operates at <<1 mA.
5. How to improve volts and amps to meet 1200 VDC and 10 A with a 10-ohm antenna?
Assuming you want to use this ATU for transmitting at 5 kHz with a 10-ohm antenna (resistance R=10 ΩR = 10 \, \OmegaR = 10 \, \Omega
), possibly with 30–40 mH inductance, let’s redesign it. Power = V2/RV^2 / RV^2 / R
, so 1200 VDC across 10 ohms implies:
P=1200210=144,000 W=144 kWP = \frac{1200^2}{10} = 144,000 \, \text{W} = 144 \, \text{kW}P = \frac{1200^2}{10} = 144,000 \, \text{W} = 144 \, \text{kW}

This is unrealistic for a small ATU, so I’ll assume 1200 V peak RF and 10 A peak current (e.g., 12 kW peak power), requiring robust upgrades.
Voltage (1200 VDC):
Capacitors: Replace with high-voltage types:
Fixed: 3500 pF total using mica capacitors (e.g., Cornell Dubilier CDV30, 2000 VDC, ~ each).

Variable: 15–150 pF air-variable capacitor, 1500 VDC+ (e.g., Oren Elliott, ~).

Switches: Use high-voltage relays (e.g., Kilovac K41C, 3500 VDC isolation, 10 A, ~ each).

PCB: Increase trace spacing to 2.5 mm (per IPC-2221 for 1200 V), use 2 oz/ft² copper.

Current (10 A):
Traces: For 10 A, 2 oz/ft² copper needs ~5 mm width (20°C rise). Add copper bus bars or redesign PCB.

Switches: Relays as above (10 A rated).

Connectors: Replace BNC with N-type or SO-239 (10 A+).

Capacitors: Ensure RF current ratings exceed 10 A (e.g., mica caps handle high RF current).

Antenna Integration (10 Ω, ~30 mH assumed):
Add 30,000 pF (1500 VDC, 10 A-rated, e.g., polypropylene film) in parallel to reach 33,500 pF for 5 kHz tuning.

Q=ωLR=2π⋅5000⋅0.0310≈9.4Q = \frac{\omega L}{R} = \frac{2\pi \cdot 5000 \cdot 0.03}{10} \approx 9.4Q = \frac{\omega L}{R} = \frac{2\pi \cdot 5000 \cdot 0.03}{10} \approx 9.4
, reasonable but lossy—consider a larger antenna for higher Q.

6. How to make it automatic (steps, parts, circuit changes)?
To automate tuning for 5 kHz with a 10-ohm antenna:

Steps:
Feedback System:
Add an RF sensor (e.g., AD8318, 1 MHz–8 GHz, ~) to measure output power or SWR.

Use a directional coupler (e.g., 5 kHz custom-built, ~) if transmitting.

Microcontroller:
Arduino Uno (~) to control tuning and process feedback.

Replace Switches:
Hex switch (16 positions): 16 SPDT relays (e.g., TE Connectivity IM06, 2 A, upgrade to 10 A types).

DIP switches: 4 relays. Control via GPIO pins and a relay driver (e.g., ULN2803, ~).

Motorize Variable Capacitor:
Attach a stepper motor (NEMA 17, ~) with driver (A4988, ~) to the 15–150 pF capacitor.

Algorithm:
Sweep relay combinations and capacitor positions.

Maximize signal (receiver) or minimize SWR (transmitter) using feedback.

Lock in settings.

Power:
12 VDC, 2 A supply (~) for relays, motor, and Arduino.

Circuit Integration:
Redesign PCB to include relay banks, motor control, and RF sensor wiring.

Add 30,000 pF fixed capacitor in parallel for 5 kHz base tuning.

Parts:
Relays: 20 × TE KILOVAC EV200 (10 A, 1500 VDC, ~ each).

Capacitors: 30,000 pF (1500 VDC, 10 A), plus upgraded 50–3500 pF bank.

Motor: NEMA 17 + A4988.

Microcontroller: Arduino Uno.

Sensor: AD8318 + coupler.

Circuit Changes:
Traces: Widen to 5 mm (2 oz/ft²) for 10 A; space 2.5 mm for 1200 VDC.

Layout: Add relay array, motor mount, and sensor input.

7. Do circuit board traces need strengthening?
Yes, for 10 A and 1200 VDC:
Current: 5 mm wide traces (2 oz/ft²) or bus bars.

Voltage: 2.5 mm spacing.

Redesign: New PCB with thicker copper and wider traces is essential for high-power operation.

Summary:
Automatic: No, it’s manual. Automate with relays, motor, and microcontroller.

5 kHz: No, needs 30,000 pF extra capacitance (33,500 pF total).

1200 VDC: No, limit ~200–500 VDC. Upgrade to 1500 VDC-rated components.

10 A: No, limit <0.5 A. Upgrade to 10 A-rated parts and traces.

10 Ω Antenna: Tunable to 5 kHz with added capacitance; 1200 V/10 A implies transmitter use.

This ATU is a receiver tool—converting it to a 5 kHz, 1200 VDC, 10 A automatic transmitter ATU is a major overhaul. Want me to refine any part further?