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Kejian KF834T-24 CATV Amplifier Module

is a hybrid RF amplifier module designed for cable television (CATV) distribution networks. It provides roughly 34 dB of power gain across a wideband 40–860 MHz range. Packaged in a flange-mount SOT115J housing, it operates from a +24 V DC supply. In practice, this part is used as a “line-extender” or forward amplifier in CATV headends and distribution amplifiers, compensating for cable loss and preserving signal quality. Key features include very good linearity, low distortion, and low noise figure, making it suitable for high-channel-count cable systems. It is internally matched to 75 Ω impedances (standard in CATV) and is bolted to a metal chassis for heat dissipation.

How EstiSource Helps

EstiSource provides specialized sourcing support for components like the KF834T-24. Its platform quickly estimates component costs and generates RFQs to suppliers. For example, EstiSource’s database can match Kejian part numbers to global stock and pricing. Procurement teams can request customized quotes and receive structured responses, leveraging EstiSource’s extensive supplier network. In practice, EstiSource helps by handling the entire sourcing cycle: it identifies legitimate sellers of KF834T-24 (avoiding counterfeits), obtains competitive pricing from multiple vendors, and ensures compliance and quality checks. Users gain “speed, structure, and cost confidence” in sourcing. By using EstiSource, an engineer or buyer can save time locating this specific CATV amplifier, compare prices across countries, and lock in supply quickly, while relying on EstiSource’s expertise in RF components.

Why Choose EstiSource for Sourcing KF834T-24

EstiSource is tailored for high-tech component procurement. It stands out by combining fast cost estimation tools with a verified supplier database. For parts like the KF834T-24, EstiSource ensures you see real market prices and can get quotes from trusted vendors at those prices. Its service gives buyers transparency (you get a quote “at the estimated price from our supplier”) and confidence. Additionally, EstiSource has deep domain knowledge in electronics sourcing: they understand CATV/RF parts, can recommend form-fit or cross-reference options, and navigate logistics. This means less risk of supply disruptions or overpaying. In short, EstiSource accelerates the sourcing process (quotes generation and supplier negotiation) while maintaining cost efficiency and quality control – making it a smart choice for OEMs and procurement teams dealing with specialized parts like the KF834T-24.

1. Material Composition

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2. Manufacturing Process

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The KF834T-24’s production follows standard CATV hybrid amplifier manufacturing steps:

Thin-Film Substrate Fabrication: Alumina (Al₂O₃) ceramic sheets are processed with photolithography and deposition to create gold conductors and laser-trimmed resistors. This substrate contains the RF matching network and bias circuitry.
Die Preparation: Semiconductor wafers (often GaAs or Si) are processed to form amplifier transistor dice. Each die is tested and qualified at the wafer level for gain, noise, and linearity. Only parts meeting strict RF specs are used.
Die Attach and Bonding: Qualified transistor die are flip-chip or wire-bond attached to the thin-film substrate. Gold wires connect the die to the printed patterns. Resistive ballasting in the die helps distribute heat evenly.
Package Assembly: The assembled substrate is mounted onto an aluminum flange (heatsink), and the leadframe is attached. The seven gold-plated leads are inserted into the flange block. A metal cap or epoxy is often applied to seal the unit.
Plating and Coating: The metal flange may be nickel- or silver-plated for corrosion resistance, and the leads are gold-plated for solderability. A silicone conformal coating or epoxy underfill can protect the circuitry from humidity.
Testing & Calibration: Each module is fully tested. DC tests verify the 210 mA operating current at 24 V. RF tests measure gain flatness, noise figure, and distortion (CTB/CSO) to ensure they meet spec (e.g. ≥33.5 dB gain at 50 MHz, noise figure ≤7.5 dB at 860 MHz). Any trimming (if needed) is done here. Known-good units are then laser-etched or marked with part codes.
Final Inspection and Packaging: The completed amplifiers undergo visual inspection and possibly burn-in for reliability. They are then packaged (often in anti-static boxes) for shipment.

Throughout production, stringent RF hybrid techniques (thin-film circuits, matched impedances, and precision assembly) are applied.

3. Challenges and Limitations

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Thermal Management

As a class-A RF power amplifier, the KF834T-24 dissipates about 5 W (24 V × ~0.21 A). It must be bolted to a heatsink or metal chassis for cooling. The mounting flange (SOT115J) conducts heat away, but the case temperature should never exceed the specified 100 °C base limit. Inadequate heat sinking can lead to performance drift or failure. Designers must calculate worst-case case/junction temperatures and ensure sufficient heatsinking or airflow.

Supply Voltage Sensitivity

The amplifier is designed for a +24 V supply and has an absolute maximum rating of 25 V. Exceeding 25 V can damage the die. Operating below 24 V lowers power consumption but will degrade linearity and output swing (as noted by its class-A bias). Supply noise or ripple must be minimized, as this directly affects the amplifier’s output.

RF Linear Performance

While the KF834T-24 offers excellent linearity for CATV (CTB ≈ –62 dB, CSO ≈ –63 dB), these limits may still be a factor in very high-channel-count systems. The noise figure (~7.5 dB at 860 MHz) is modest – low enough for most cable uses but not negligible. Designers may need additional filtering or equalization to compensate for any frequency-dependent gain slope (≤1 dB slope from 50–860 MHz) or ±0.4 dB flatness variation.

Mechanical Constraints

The metal flange is not meant to be trimmed or machined – attempting to lap or file it can crack the ceramic substrate. Users should apply even torque on mounting screws and avoid excessive stress. Likewise, the device is not hermetically sealed; if used outdoors or in humid environments, corrosion-resistant coatings or enclosures are recommended.

Mounting and Impedance

The amplifier is specified for 75 Ω systems. Using it with other impedances will degrade VSWR/return loss (input RL ≥16–18 dB). Its physical footprint (about 27×13×20 mm with two screw holes) also means it takes a fair amount of PCB/chassis space compared to smaller ICs.

Availability

Kejian components are relatively specialized. Sourcing might be limited to certain distributors or brokers. This can pose procurement challenges, making advanced planning or second sources important.

4. Costing

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5. Properties and Characteristics

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Frequency Range

Broad 40–860 MHz coverage to span the full CATV downstream band.

Power Gain

Approximately 34 dB gain (typical) across the band. For example, ~34.0 dB gain at 50 MHz and similar at 860 MHz.

Noise Figure

Around 7.5 dB at the top end (860 MHz). Noise figure increases with frequency; lower NF at midband ensures good signal-to-noise ratio in cable systems.

Return Loss (VSWR)

Input return loss is ≥18 dB for 40–700 MHz (≥16 dB up to 860 MHz). Output return loss is ≥16 dB (40–700 MHz). These imply ~75 Ω match with minimal reflections in-band.

Linearity/Distortion

CTB (composite triple beat) ~ –62 dB, CSO (composite second-order) ~ –63 dB, cross-modulation ~ –61 dB, measured at 44 dBmV output. This indicates high linearity suitable for 60+ channel operation, though high-end systems may still use predistortion.

Frequency Flatness

Frequency response flatness is ±0.4 dB over 40–860 MHz, ensuring uniform amplification across channels. The gain slope is ~0.5–1.0 dB (cable-eq) over the band.

Supply Voltage

Designed for +24 V DC (nominal). Absolute max is +25 V.

Current Consumption

About 210 mA typical at 24 V (i.e. ~5 W power). Range is roughly 200–235 mA depending on unit.

Temperature Range

Operational mounting-base temperature from –40 °C to +100 °C. Storage –20 °C to +100 °C. (Proper heatsinking is critical to stay within these limits.)

Package

SOT115J (single-ended flange-mount). Dimensions ~27×13×20 mm with two vertical screw holes (6-32 UNC) and two horizontal holes. Color/finish is aluminum (often anodized) with gold-plated leads.

Physical

Total internal components include laser-trimmed chips, making the module highly reliable but not serviceable in the field. It’s a sealed hybrid module (non-adjustable by user).

6. Frequently Asked Questions

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Q: What is the Kejian KF834T-24 used for?

It’s a forward CATV amplifier (line extender) IC module. It boosts broadband cable TV signals (40–860 MHz) in distribution amplifiers or nodes.

Q: What gain and frequency range does KF834T-24 provide?

It provides about 34 dB gain and covers the full CATV band 40–860 MHz. The gain is roughly flat over this range (±0.4 dB variation).

Q: What supply voltage and current does it need?

KF834T-24 requires a +24 V DC supply. It draws about 200–210 mA typically (up to ~235 mA max), or roughly 5 W. The absolute max supply is +25 V.

Q: How is the part packaged and mounted?

It comes in a flange-mount SOT115J package. You bolt the aluminum heat-sink body directly to a metal chassis (using the provided screw holes) for cooling. The seven gold-plated leads protrude for PCB or backplane connection.

Q: Can the KF834T-24 be used for upstream/return path signals?

No – this model is a forward-path amplifier (downstream). Its frequency range (40–860 MHz) and design are meant for CATV forward channels. It is not configured for the narrowband or low-frequency return path (5–42 MHz).

Q: Are there similar Kejian amplifier modules?

Yes. Kejian makes related modules like KF834N-24, which has the same 40–860 MHz range and ~34 dB gain at 24 V. (The “N” and “T” variants differ in tuning or network configuration but have similar specs.) Other variants exist for 6 V or 3.5 V supply, or with optical inputs, as cataloged by suppliers.

Q: What performance should I expect (noise/distortion)?

At 44 dBmV output, expect composite triple beat (CTB) around –62 dB and composite second-order (CSO) around –63 dB, which is typical for a high-quality CATV forward amp. The noise figure is about 7.5 dB at 860 MHz. These values mean very clean amplification for most cable systems.

Q: How do I source this part and ensure I get authentic units?

Because Kejian is a niche supplier, careful sourcing is important. Use authorized distributors or specialized brokers. Cross-verify part markings and supplier reputation. Consider contacting experts like EstiSource to access their verified network and cost estimates.