Published on 10/13/2026
A cable assembly is specified for an under-hood sensor at 125 C. The datasheet lists the dielectric as PTFE, which is fine, and the jacket as PVC, which is not. The signal still works on day one, then the jacket softens, cracks and exposes the braid. Temperature ratings belong to every layer, and the lowest one wins.
Short answer: PVC jackets are rated about -40 to +80 C, polyethylene about -55 to +85 C, and FEP and PTFE about -65 to +200 C. Silicone jackets reach about +180 C. Cable operating range is set by the weakest layer: jacket, dielectric, braid plating or connector.
The table below lists typical limits by jacket and dielectric. Check the datasheet of the exact cable.
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| Jacket material | Typical range (C) | Notes |
|---|---|---|
| PVC | -40 to +80 (some to +105) | Low cost; stiffens in cold |
| Polyethylene (PE) | -55 to +85 | Good UV resistance, outdoor use |
| Polyurethane (PU) | -40 to +90 | Abrasion and oil resistance |
| LSZH (low smoke zero halogen) | -40 to +70 (some to +105) | Fire-safety use; check grade |
| Cross-linked polyolefin | -55 to +125 | Heat and chemicals |
| Silicone | -60 to +180 | Very flexible; low abrasion strength |
| FEP | -65 to +200 | RG316, RG400, RG142 class |
| PTFE | -65 to +200 (up to 250 for some) | Highest range; costly |
Ranges are typical and vary by compound. Always read the datasheet.
| Layer | Typical limit | Effect beyond limit |
|---|---|---|
| Solid PE dielectric | About 85 C | Softens, center conductor migrates |
| Foam PE dielectric | About 80 to 85 C | Collapses, impedance shifts |
| PTFE dielectric | About 200 C or higher | Very stable |
| Silver-plated copper braid | Up to 200 C | Stable |
| Tin-plated braid | Up to about 150 C | Oxidizes at high temperature |
| Standard connectors (PTFE, gold) | About 165 C | Check connector spec |
| Solder joints (tin-lead or lead-free) | About 150 C working | Weakens near reflow range |
Key idea: The usable range of an assembly is the lowest rating among cable, connector, solder and cable-to-connector bond. Check each.
PTFE and FEP assemblies built to order
Tell us the temperature range and frequency. We will build the assembly and sweep it on a VNA for VSWR and insertion loss before shipment.
Talk to an EngineerCold makes PVC stiff and brittle. A cable rated to -40 C should not be flexed at that temperature. FEP and PTFE keep their flexibility to about -65 C. Silicone stays flexible below -60 C. Handle and install cable at room temperature when possible.
| Environment | Recommended |
|---|---|
| Outdoor, -40 to +70 C | PE jacket cables (RG213, LMR with PE) |
| Under hood or industrial, to +125 C | FEP or cross-linked jacket |
| Aerospace, to +200 C | PTFE or FEP with silver-plated braid |
| Cryogenic | Specialty PTFE or semi-rigid; check shrinkage |
Loss rises slightly with temperature because conductor resistance increases. For copper, resistance rises about 0.4 percent per degree C, so loss rises about 0.2 percent per degree C because loss follows the square root of resistance. From 25 C to 125 C that is about 20 percent more loss. PTFE cables also show a small phase change near 19 C where the dielectric changes crystal structure, which matters for phase-matched cables.
Avoid
What is the temperature rating of RG58?
Typically -40 to +80 C with a PVC jacket, or up to +85 C for PE jacket versions.
What is the temperature range of RG316?
About -55 to +200 C, because of the PTFE dielectric and FEP jacket.
What is the maximum temperature for PTFE cable?
About 200 C for most cable, and up to 250 C for special versions.
Does temperature change coax loss?
Yes. Loss rises about 0.2 percent per degree C for copper conductors.
Which coax cable is best for high temperature?
PTFE or FEP cables such as RG316, RG400 and RG142, or semi-rigid cable.
What jacket is best for cold weather?
FEP, PTFE, silicone or PE. PVC gets stiff below about -20 C.
Read the temperature rating of every layer, not just the jacket or dielectric. Use PE for outdoor, FEP or PTFE for heat, and check connectors and solder for the full assembly.
SigmaRF builds high-temperature assemblies in India (Vadodara) and the USA (Cleveland area), VNA-swept before shipment, with lead times as short as 2 days.
Need a heat-rated assembly?
Send the temperature range and frequency.
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