Klystrons & Travelling-Wave Tubes
Look for a blue-tinted or coloured-ring-marked ceramic section, or a BERYLLIUM OXIDE label — that tube is a disposal problem, not scrap; and if the serial plate and a satcom/medical/radar part number are intact it is worth 10–100× more sold as a tube.
How to spot it
Klystron: a 0.3–2 m metal-and-ceramic cylinder with stacked doughnut-shaped copper cavities, a finned or water-jacketed collector at one end, a ceramic HV gun insulator at the other, a waveguide or coax output and a heavy magnet assembly. TWT: 150–600 mm, slender, surrounded by a periodic stack of ring magnets and iron pole pieces. Markings VA-/VKP- (Varian), CPI, EEV/e2v, Thales, L-3, Litton, TH-, plus radiation trefoils and BeO labels. Found in radar, satcom earth stations, medical linacs, EW pods and UHF transmitters.
Metal content
| Metal | Quantity | Notes |
|---|---|---|
| Copper | ~250 g/lb (0.35–0.75 lb Cu per lb of tube) | OFHC body, cavities and collector — the dominant real value |
| Gold | ~0.5–4 g per tube | Ceramic-to-metal seal brazes only; estimate, no published assay exists |
| Silver | 2–30 g per tube | Silver brazes throughout; some cavities silver-plated |
At 4 Aug 2026 spot prices that works out to $5.59 per pound of contained metal — Copper 250 g = $2.67, Gold 0.02 g = $2.61, Silver 0.16 g = $0.30. A refiner paying $2 returns about 36% of that, which is normal: refining costs money and the buyer takes a margin.
Safe removal
Working temperature: No heat permitted — cold mechanical teardown only
Never attempt to open a vacuum tube. If dismantling for copper: confirm no BeO from markings and datasheet, discharge and ground all HV, work under LEV, vent the vacuum by slowly cutting the pinch-off tubulation with a cutter not a grinder, unbolt rather than cut, segregate thoriated tungsten parts, and wet-wipe everything. No sawing, grinding or torching of any ceramic, ever.
Hazards
NEVER grind, sand, file, saw, drill, abrasive-cut, sandblast, hammer, crush, shred, torch, melt or incinerate anything that might contain BeO. Sell or dispose of suspect parts intact. Broken beryllium parts are worth nothing; your lungs are worth everything.
NEVER short a large capacitor with a screwdriver. It welds the tip, blasts molten metal at your face, and can rupture the can.
NEVER grind, sand, saw or incinerate anything that might contain thorium or radium. Sealed sources stay sealed.
NEVER vacuum a mercury spill — it aerosolises it. Use a mercury spill kit or sulphur powder, or call your local hazmat line.
NEVER puncture, drain, burn or bin a suspect unit. Burning PCBs produces dioxins and furans.
NEVER blow on, wipe with bare fingers, or brush away cut optical fibre.
Don't let two magnet plates snap together across your fingers.
NEVER crack a hydraulic or refrigerant line without confirming the system is depressurised.
Before you scrap it
The common trap
Questions
How much gold is in klystrons & travelling-wave tubes?
Copper: ~250 g/lb (0.35–0.75 lb Cu per lb of tube). Gold: ~0.5–4 g per tube. Silver: 2–30 g per tube. At current spot that is about $5.59 of contained metal per pound.
How do you identify klystrons & travelling-wave tubes?
Look for a blue-tinted or coloured-ring-marked ceramic section, or a BERYLLIUM OXIDE label — that tube is a disposal problem, not scrap; and if the serial plate and a satcom/medical/radar part number are intact it is worth 10–100× more sold as a tube.
How do you remove klystrons & travelling-wave tubes safely?
Never attempt to open a vacuum tube. If dismantling for copper: confirm no BeO from markings and datasheet, discharge and ground all HV, work under LEV, vent the vacuum by slowly cutting the pinch-off tubulation with a cutter not a grinder, unbolt rather than cut, segregate thoriated tungsten parts, and wet-wipe everything. No sawing, grinding or torching of any ceramic, ever.
Is klystrons & travelling-wave tubes worth more working than as scrap?
Overwhelmingly the right move — 10–100×. Medical linac klystrons rebuild for $20,000+, satcom TWTAs and radar TWTs pull $1,000–8,000, and even untested identifiable tubes fetch $200–1,500 from RF surplus dealers. A 100 lb klystron is $300 of copper or $3,000 as a tube.
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