How to Tune the PulseRoot 100 with a 9V Battery and 2 Resistors
The PulseRoot 100 Terminator is a passive adaptive terminator for PulseRoot 100 RX antenna (an active Beverage-on-Ground (BOG)). This guide explains how to measure soil resistance and properly tune your PulseRoot 100 Terminator installation with just simple tools: a 9V battery, a 1kΩ resistor (included), a 10kΩ resistor (included) and a voltmeter
Tools You Need:
- 9V battery (fresh)
- 1kΩ resistor (1/4W or higher)
- 10kΩ resistor (1/4W or higher)
- Voltmeter (DC mode, 0-10V range)
- 2 crocodile clips (to connect to the PulseRoot pegs)
Important:
- Ensure NO terminator is connected to the PulseRoot pegs during measurement.
- Only connect to the RVS probe pegs.
Connection Setup
Connect everything as follows:
9V Battery (+)
|
[Reference Resistor] (1kΩ or 10kΩ)
|
[RVS Probe A (Peg A)]
|
[The SOIL (between the probes)]
|
[RVS Probe B (Peg B)]
|
9V Battery (-)
- Connect the crocodile clips to the two RVS pegs.
- Insert the reference resistor between the 9V positive and Peg A.
- Connect the negative battery terminal to Peg B.
- Measure the voltage across Peg A and Peg B with your voltmeter.
How to Measure
- Connect 1kΩ resistor first.
- Read the voltage on the voltmeter.
- Use the reference table to find soil resistance.
- If the voltage is very close to 9V (very dry soil), switch to 10kΩ resistor for better accuracy.
Reference Table
| Voltage across soil (V) | Soil resistance (Ohms) with 1kΩ ref | Soil resistance (Ohms) with 10kΩ ref |
|---|---|---|
| 0.5 V | 59Ω | 590Ω |
| 1.0 V | 111Ω | 1111Ω |
| 1.5 V | 176Ω | 1764Ω |
| 2.0 V | 250Ω | 2500Ω |
| 2.5 V | 333Ω | 3333Ω |
| 3.0 V | 429Ω | 4286Ω |
| 3.5 V | 538Ω | 5385Ω |
| 4.0 V | 666Ω | 6666Ω |
| 4.5 V | 818Ω | 8181Ω |
| 5.0 V | 1000Ω | 10,000Ω |
| 6.0 V | 1500Ω | 15,000Ω |
| 7.0 V | 2333Ω | 23,333Ω |
| 8.0 V | 4000Ω | 40,000Ω |
Practical Tips:
- Typical wet soil: 300Ω to 700Ω.
- Normal soil after rain: around 500Ω.
- Dry soil: 2kΩ or more.
- No terminator must be connected during measurement!
- The RVS rods must be properly inserted 15-50cm apart into the soil depending your measurements. (on our tests 30cm is the sweat spot, but results may vary)
After Measurement:
- Once soil resistance is known, and the rods are positioned correctly reconnect the PulseRoot 100 terminator.
- The terminator will passively adapt to wet/dry conditions based on the installation.
This method ensures your PulseRoot 100 works at maximum efficiency without special tools, field computers, or analyzers!
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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.