An outdoor CATV amplifier is the least glamorous line in a network bill of materials, and the one most often bought on price alone. That works until the fourth summer, when a unit quoted at a comfortable output level turns out to have been measured at 25 °C with two carriers loaded. Seven lines, and what each costs you.
Price First: Every Datasheet Line Is a Cost Line
The price is set by five things: forward bandwidth, output capability (the RF power devices and heatsink), output port count, AGC or thermal compensation, and the housing and surge design.
That is why two amplifiers sold as "1 GHz, 34 dB" can cost very differently: one is a two-port line extender with no compensation, the other a four-port bridger with AGC. Compare price per usable output port at a stated output level and tilt — not price per box.
1. Forward Bandwidth: 870 MHz, 1 GHz, 1.2 GHz
A 1.2 GHz HFC platform is what the top of DOCSIS 3.1 needs, and DOCSIS 4.0 pushes further. But a wideband amplifier on an 870 MHz lineup draws more current for spectrum nobody is loading. Buy the bandwidth of the next three years, not the next decade — where the plant is rebuilt for DOCSIS 3.1 anyway, the wider platform is cheaper over its life.
2. Gain vs Output Level — Two Different Numbers
Gain (30, 34, 38 dB) is how much the unit amplifies; output level is what it delivers before distortion. A high-gain amplifier is not a high-output one, and extra gain bought to "cover" a badly designed span spends the distortion budget instead of the cable budget. Match gain to span loss at the highest frequency.
3. Output Level — Never Accept It Without Conditions
This is the most abused number on any datasheet. "106 dBµV" alone means nothing. A defensible specification states four conditions:
- Channel loading — carrier count, and whether analog or digital
- Tilt at that level — for example 10 dB across the band
- Test point — the amplifier output, not the end of the cascade
- Distortion criterion — CSO and CTB for analog, MER where the load is digital
The same unit quoted under different conditions lands 4–6 dB apart. When a quote is 5 dB better than everyone else's, ask for the conditions.
4. Noise Figure — The Cascade Math
CNR is a budget: total CNR is roughly the single-unit value minus 10·log₁₀(N). Eight amplifiers in cascade cost about 9 dB against one. Distortion accumulates the other way — CSO and CTB grow with amplifier count and output level, which is why the last units are set several dB lower.
And noise figure at 25 °C is not noise figure at 60 °C: gain falls as the housing heats unless the unit compensates.
5. Tilt, Slope and Thermal Compensation
Tilt compensates the higher cable loss at high frequency. Across a 40 °C swing, loss at 1 GHz moves by several dB, so without compensation the output level walks with the weather.
- MGC — fixed attenuation, lowest cost, needs a seasonal re-alignment visit.
- Thermal compensation — gain and slope corrected against housing temperature.
- AGC or ALC with a pilot carrier — closed loop.
Ask for the compensation range in dB, not for a tick in a box.
6. Return Path and the Diplex Split
Where the plant carries DOCSIS, the diplex split decides the return bandwidth you actually get: 42/54 MHz on legacy plant, 85/102 MHz for mid-split, 204/258 MHz for high-split DOCSIS 3.1 and 4.0. Forward and return band are one purchasing decision: an upgrade that keeps a 42 MHz return blocks the next DOCSIS step.
7. Powering, Surge and the Housing
- Power — 60 V AC over the coax, or local 220/230 V AC. Decide per site.
- Current draw at your actual AC input, not at nominal.
- Surge — a stated withstand quoted to a waveform (6 kV, 1.2/50 µs is a common reference). Ask what the unit survives, not what it is "protected against".
- Housing — die-cast aluminium, a stated IP rating, sealed connectors. Salt fog is a separate problem.
Where the Amplifier Sits: HFC vs FTTH
In HFC, the coax from node to MDU riser is amplifier territory: trunk or bridger at the node, line extenders down the feeder. In FTTH on GPON or XGS-PON, coax gives way to fiber and the broadcast video rides at 1550 nm to an optical receiver — a 1550 nm RF video overlay — so the amplifier count falls. Where in-building coax stays, RFoG returns the path to fiber, and return alignment matters more, because ingress tolerable on a coax return becomes a shared impairment.
Lead Time and MOQ
Catalogue configurations typically ship in 3–7 working days, expedited for project schedules. Configured units are bounded by the configuration freeze — connector, diplex split, port count, branding.
MOQ follows customization rather than the carton. The useful question is not "what is your MOQ" but which items are true catalogue configurations you can reorder at short notice.
[待用户补充：各产品线实际 MOQ 与阶梯价格结构 —— 本篇只写"MOQ 由定制程度决定"这一通用判断，未给出任何具体数量。]
The Paperwork Line
Emerging markets are lighter on EMC regimes than the EU or North America, but several run national type-approval schemes — ANATEL in Brazil, IFT in Mexico, SASO in Saudi Arabia — and most projects want the paperwork before the hardware ships.
In Europe: CE marking with EMC assessed to EN 50083-2, RoHS 2 (Directive 2011/65/EU), WEEE take-back and REACH declarations. In North America: FCC Part 15 (Class B residential, Class A headend), NRTL listing to UL or ETL, SCTE practices for the RF interface, and California Prop 65 disclosure. Those are what those markets require of the equipment.
HENSURE is CE certified and RoHS compliant; a DoC and the RoHS report are available on request.
[待用户补充：CE 证书编号 / 签发机构 / DoC 引用的协调标准；RoHS 报告编号与出具实验室。]
Spec Sheet Reading Checklist
| Line on the sheet | What to demand | Why it decides money |
|---|---|---|
| Bandwidth | Upper frequency, and the diplex split | A second rebuild |
| Gain | dB, at which frequency | Mismatched gain |
| Output level | dBµV + channel count + tilt + test point | 4–6 dB of real margin |
| Noise figure | dB, at a stated ambient temperature | Cascade CNR budget |
| Temperature | Operating range and derating curve | Output at 55 °C |
| Compensation | MGC, thermal or AGC, range in dB | Seasonal truck rolls |
| Power and surge | AC input options, current draw, withstand waveform | Site supply, lightning |
| Documentation | Per-unit test report, RoHS report | Evidence at an RMA |
The One-Paragraph Version
Ask for output level with its channel loading and tilt, for noise figure with its ambient temperature, and for what the unit still delivers at 55 °C. Then compare price per output port at that level. An amplifier bought on the headline number is one you will buy twice.
If you are specifying amplifiers for a 1.2 GHz HFC upgrade, a tropical rebuild or an MDU retrofit, send your span lengths, channel plan and ambient temperature range and our engineering team will return the gain, tilt and output level that fit — with the test conditions written down.