Source: https://guthlabs.ai/docs/instruments/coax-cable-loss-power-handling-estimator/mechanism/

instrument mechanism / verified-clean

# Coax Cable Loss & Power Handling Estimator mechanism

The inspectable method record for Coax Cable Loss & Power Handling Estimator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The loss and transmitted-power arithmetic is standard and internally consistent, but the instrument cannot honestly claim to compute power-handling derating until it includes manufacturer power-rating data and an explicit derating method. Results also require a concrete cable manufacturer/part number and a versioned attenuation table. The honest label should state that values are nominal manufacturer attenuation estimates and should separately disclaim connector loss, mismatch, temperature, aging, installation effects, and power-handling safety limits.

- The loss formula is correct when attenuation_per_100ft is expressed in dB per 100 ft and length is in ft: total_loss_dB = attenuation_per_100ft × length_ft/100.

- The output power formula Pout = Pin × 10^(-Loss/10) is the standard matched-system conversion from insertion loss in dB to power ratio.

- The efficiency output is not explicitly defined; it should be efficiency_percent = 100 × 10^(-Loss/10) = 100 × Pout/Pin for Pin > 0.

- The claimed power-handling derating calculation is missing. Cable attenuation loss alone does not calculate allowable power handling; a manufacturer maximum-power table and a temperature/frequency/VSWR derating formula or rule are required.

- Frequency lookup and interpolation behavior is unspecified. Linear interpolation in dB is assumed below, but some manufacturer data sheets provide only discrete maximum values and do not guarantee linear interpolation between them.

- Cable-specific data are not supplied in the specification, so numerical results cannot be uniquely reproduced for RG-58, LMR-400, or other named cable types without selecting a particular manufacturer, part number, and table revision.

## Units and conventions

- Length is supplied in feet because the attenuation lookup unit is dB per 100 ft; if length is supplied in metres, it must first be converted using 1 m = 3.280839895 ft.

- Frequency is supplied in MHz and must be within the selected cable's published table range.

- Pin is available RF power in watts at the cable input, assumed positive and referenced to a matched system.

- Attenuation values are maximum nominal manufacturer values at the stated reference conditions, not guaranteed field loss including connectors, mismatch, temperature, aging, or installation effects.

- Efficiency means transmitted power divided by incident input power, expressed as a percentage; it excludes reflected power and connector losses unless those are included in the attenuation table.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "cable_type": "LMR-400",
    "length_ft": 100,
    "frequency_MHz": 150,
    "Pin_W": 10
  },
  "expected_outputs": {
    "total_loss_dB": 0.9,
    "Pout_W": 8.128305,
    "efficiency_percent": 81.28305
  },
  "reference_data": {
    "LMR-400_attenuation_dB_per_100ft_at_150MHz": 0.9,
    "source_convention": "widely tabulated standard value; Times Microwave Systems LMR-400 manufacturer attenuation-maximum table"
  },
  "working": "The lookup is exactly at the 150 MHz table row: attenuation = 0.9 dB/100 ft. length factor = 100/100 = 1. Total loss = 0.9 × 1 = 0.9 dB. Power ratio = 10^(-0.9/10) = 10^(-0.09) = 0.8128305. Pout = 10 W × 0.8128305 = 8.128305 W. Efficiency = 100 × 0.8128305 = 81.28305%."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification does not provide actual attenuation tables, valid frequency ranges, interpolation or extrapolation rules, explicit input units, or a defined response for out-of-domain frequencies. These omissions permit undefined results or materially different outputs, especially at zero frequency and when length or input power conventions are misread.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/coax-cable-loss-power-handling-estimator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/coax-cable-loss-power-handling-estimator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/coax-cable-loss-power-handling-estimator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`