HT309 Luxmeter User Manual

1. Precautions and Safety Measures

The instrument is designed in compliance with safety directives for electronic measuring instruments. To prevent damage, follow manual procedures and pay close attention to notes preceded by the [caution-symbol]. Observe the following instructions before and after measurements:

• Do not measure in environments with gas, explosive materials, flammables, or dust.
• Do not measure in humid environments.
• Do not measure if anomalies like deformation, breaks, leaks, or display absence are found.
• Do not touch the photodiode sensor during measurements to prevent damage from static electricity or contamination.

The following symbol is used: [caution-symbol]: Observe instructions; improper use may damage the instrument or its components.

1.1. Preliminary Instructions

To prevent incorrect readings, replace the battery when the [low-battery-symbol] appears on the display during startup.

1.2. During Use

Please read the following recommendations and instructions.

CAUTION: Failure to comply with caution notes or instructions may damage the instrument, its components, or endanger the operator.

While measuring, if the value or sign remains unchanged, check if the HOLD function is enabled.

1.3. After Use

• Switch off the instrument when measurement is complete.
• If the instrument will not be used for a long time, remove the battery.

2. General Description

The HT309 is a precision digital luxmeter used for measuring illuminance of white light and colored LED sources, expressed in Lux (Lx) or Foot-candles (Fc). It complies with CIE standards for spectrum response and corrects for the angle of incidence of light. The silicon photodiode sensor ensures measurement stability.

Functions include:

• Illuminance measurement up to 400kLux / 40kFc
• Luminous intensity measurement (in Candles)
• Selection of measuring units: Lx/Fc/CD
• Support for white light and LED sources in the visible spectrum
• High-precision and rapid measurements
• Data HOLD function
• MAX/MIN/AVG functions
• Zeroing of displayed value
• Internal memory for saving results
• Auto Power OFF
• Backlight
• Autorange

3. Preparation for Use

3.1. Initial Checks

The instrument is checked for electrical and mechanical integrity before shipping. Inspect for any damage sustained during transport. Contact the forwarding agent for anomalies. Verify that all components listed in § 7.3 are present. Contact the dealer for discrepancies. Follow instructions in § 8 for returns.

3.2. Instrument Power Supply

The instrument is powered by a single 9V alkaline battery (NEDA1604, JIS006P, IEC6F22), included but not inserted. For battery installation, see § 6.1. The [low-battery-symbol] indicates a flat battery. Replace the battery following § 6.1.

3.3. Storage

For precise measurements after long storage or extreme environmental conditions, allow the instrument to return to normal conditions (see § 7.2.1).

4. Nomenclature

4.1. Instrument Description

Figure 1: Instrument description

The physical layout of the HT309 luxmeter includes:

• 1. Input terminal: Connection point for the sensor.
• 2. LCD display: Shows measurement values and status indicators.
• 3. LX/FC/CD key: Selects illuminance units (Lux/Fc) or luminous intensity (CD).
• 4. MAXMIN key: Accesses Minimum, Maximum, and Average values.
• 5. HLD key: Freezes the current displayed value (HOLD function).
• 6. MEM/READ key: Saves or recalls data from internal memory.
• 7. [Up Arrow Symbol]: Navigation key.
• 8. /SRC key: Activates/deactivates backlight or selects light source.
• 9. [Down Arrow Symbol]: Navigation key.
• 10. ZRO key: Performs automatic zeroing of the display.
• 11. ON/OFF key: Turns the instrument on/off and disables Auto Power OFF.
• 12. Photodiode sensor: The light-sensitive component.

4.2. Display Description

Figure 2: Display description

The information shown on the LCD display includes:

• 1. M symbol (Memory): Indicates data is saved in memory.
• 2. Location number: Shows the memory storage location.
• 3. HOLD function active: Indicates the display is frozen.
• 4. R symbol (Recall): Indicates data is being recalled from memory.
• 5. MAX, MIN, AVG functions active: Shows which statistical function is active.
• 6. APO function active: Indicates the Auto Power OFF feature is enabled.
• 7. Illuminance measurement unit: Displays the current unit (Lux or Fc).
• 8. Main display: Shows the primary measurement value.
• 9. Secondary display: Shows additional information, like light source type or memory location.
• 10. Low battery indication: Shows when the battery needs replacement.
• 11. Light source type: Indicates the type of light source being measured.
• 12. Distance measurement unit: Displays the unit for distance (m or ft).
• 13. Source coefficient: Displays the correction factor for the selected light source.

4.3. Description of Function Keys

4.3.1. ON/OFF Key

Press to turn the instrument on or off. Also used to disable the Auto Power OFF (APO) feature (see § 4.3.9).

4.3.2. LX/FC/CD Key

Press to select illuminance units (Lux or Fc; 1Fc = 10.764Lux; 1Lux = 0.09290Fc). Press and hold (>1s) to select luminous intensity unit (Candela, CD) (see § 5.2).

4.3.3. HLD Key

Press to freeze the measured value on the display. The "HOLD" symbol appears. This function is inactive when MAX, MIN, or AVG features are enabled.

4.3.4. MEM/READ Key

Press to save the current display value to internal memory. The memory location number and "M" symbol appear briefly. Press and hold LX/FC/CD (>1s) to recall saved data. The "R" symbol and memory location number appear. Use arrow keys [up-arrow-symbol] or [down-arrow-symbol] to select memory locations. Press and hold LX/FC/CD (>1s) again to exit recall mode.

4.3.5. Deleting the Internal Memory

To delete memory:

1. Switch off the instrument using the ON/OFF key.
2. Press and hold the MEM/READ key while switching the instrument on with the ON/OFF key. The display will show "CLR" briefly, and the memory location resets to "00".

4.3.6. MAXMIN Key

Press to view Minimum, Maximum, and Average (AVG) values. Values update cyclically with each press. "MIN", "MAX", and "AVG" symbols appear. Press and hold MAXMIN (>1s) to exit.

4.3.7. ZRO Key

Press to automatically zero the display. Use when the "000" indication is absent with the protection cover on the sensor. "AdJ" is shown during zeroing. "CAP" is shown if ZRO is pressed without the cover; place the cover and repeat.

4.3.8. /SRC (Light Source) Key

Press to activate/deactivate the display backlight. Press and hold (>1s) to select the light source for measurement. Follow these steps:

1. Observe the flashing "Lx" symbol on the sub-display (x = source number 0-9).
2. Use arrow keys [up-arrow-symbol] or [down-arrow-symbol] to select the source (L0-L9).
3. Press /SRC to set a correction factor for custom sources (L7-L9). The value flashes; use arrow keys to set between 0.001 and 1.999. L0-L5 values are fixed.

Press and hold /SRC (>1s) to confirm. Source symbols stop flashing.

4.3.9. Disabling the Auto Power OFF Function

The instrument automatically switches off after 5 minutes of inactivity, indicated by the [auto-power-off-symbol]. To disable this:

• Switch on the instrument.
• Press and hold the ON/OFF key (>1s). The [auto-power-off-symbol] disappears.
• Press and hold ON/OFF (>1s) again, or switch off and on, to re-enable the function.

5. Operating Instructions

5.1. Illuminance Measurement

1. Place the protection cover on the photodiode sensor.
2. Switch on the instrument using the ON/OFF key.
3. If necessary, zero the display using the ZRO key (see § 4.3.7).
4. Select Lux or Fc units using the LX/FC/CD key (see § 4.3.2).
5. Select the light source type by pressing and holding the /SRC key for over 1 second (see § 4.3.8). The standard source is "L0".
6. Position the sensor horizontally and perpendicularly to the source. The illuminance value is displayed with automatic scale change.
7. Press HLD (see § 4.3.3) to freeze the displayed value if needed.
8. Press MEM/READ (see § 4.3.4) to save the real-time value to memory.
9. Cover the sensor and switch off the instrument after measurement.

5.2. Luminous Intensity Measurement

Luminous intensity (Candela, CD) is calculated using the formula:

Luminous intensity (CD) = Illuminance (Lux/Fc) x Distance from source (m²/ft²)

1. Place the protection cover on the photodiode sensor.
2. Switch on the instrument using the ON/OFF key.
3. If necessary, zero the display using the ZRO key (see § 4.3.7).
4. Select the "CD" unit by pressing and holding the LX/FC/CD key (1s) (see § 4.3.2).
5. Use arrow keys [up-arrow-symbol] or [down-arrow-symbol] to select the distance unit ("m" or "ft") and confirm with LX/FC/CD.
6. Select the light source type by pressing and holding the /SRC key for over 1 second (see § 4.3.8). The standard source is "L0".
7. Set the distance between the measurement point and the light source using arrow keys [up-arrow-symbol] or [down-arrow-symbol] (range: 0.01m to 30.347m or 0.01ft to 99.99ft) and confirm with the LX/FC/CD key.
8. Position the sensor horizontally and perpendicularly to the source. Luminous intensity is displayed with automatic scale change.
9. Press HLD (see § 4.3.3) to freeze the displayed value if needed.
10. Press MEM/READ (see § 4.3.4) to save the real-time value to memory.
11. Cover the sensor and switch off the instrument after measurement.

6. Maintenance

CAUTION: Only expert and trained technicians should perform maintenance. Disconnect all cables before maintenance.

• Do not use the instrument in high humidity or high temperatures. Do not expose to direct sunlight.
• Always switch off the instrument after use. Remove the battery if storing for a long time to prevent leaks that could damage internal circuits.

6.1. Battery Replacement

When the [low-battery-symbol] appears on the display, replace the battery:

1. Switch off the instrument.
2. Remove the temperature probe (if applicable).
3. Remove the battery cover.
4. Remove the old battery.
5. Insert the new battery into the fastener and return it to the case.
6. Replace the battery cover.
7. Dispose of the old battery according to local regulations.

6.2. Cleaning the Instrument

Use a soft, dry cloth. Never use wet cloths, solvents, or water. The sensor's white plastic lens can be cleaned with a damp cloth if necessary.

6.3. End of Life

CAUTION: The [end-of-life-symbol] on the instrument indicates that the appliance, battery, and accessories must be collected and disposed of separately and correctly.

7. Technical Specifications

7.1. Technical Characteristics

Accuracy is specified under reference conditions: 25°C (77°F) and <70% RH.

The instrument is calibrated for a standard white light source (incandescent lamp, 2856°K, Class A). LED source calibration uses correction factors from Table 1.

Illuminance Measurement (Autorange)

Illuminance Measurement (Fc)

NOTE 1: 1Fc = 10.76Lux, 1Klux = 1000Lux, 1Kfc = 1000Fc

NOTE 2: Accuracy is 6% reading for temperatures/colors different from the reference.

Distance range for luminous intensity measurement: 0.01 ÷ 30.47m / 0.01 ÷ 99.99ft

Accuracy on Angular Deviation from Cosine Characteristic

7.1.1. Spectrum Response

The spectrum response of the photodiode with filter closely matches the CIE V(λ) curve. The graph shows relative sensitivity (%) versus wavelength (nm). The HT309 curve is shown alongside the standard CIE curve.

7.1.2. Sensor

The sensor is a silicon photodiode with a filter for spectrum response.

7.1.3. General Characteristics

Mechanical Characteristics

• Dimensions (L x W x H): 190 x 65 x 45mm (7 x 3 x 2in)
• Sensor dimensions (L x W x H): 110 x 60 x 35mm (4 x 2 x 1in)
• Cable length: approx 1.5m (39in)
• Weight (battery included): 235g (8 ounces)

Power Supply

• Battery type: 1x9V NEDA 1604, IEC 6F22
• Low battery indication: [low-battery-symbol] on display.
• Battery life: approx 60h (backlight ON), approx 180h (backlight OFF).

Display

• Characteristics: LCD, 6 digits, 4000 dots plus decimal point.
• Over range indication: "OL" on display.
• Sampling rate: 2.5 measurements/s.

Considered Standards

• EMC: IEC/EN61326-1, IEC61000-4-2, IEC61000-4-3
• Reference standard: JIS C 1609:1993 and CNS 5119 general specification in Class A.
• Pollution level: 2.

This instrument satisfies EMC Directive 2014/30/EU and European Directives 2011/65/EU (RoHS) and 2012/19/EU (WEEE).

7.2. Environment

7.2.1. Environmental Conditions for Use

• Reference temperature: 25°C (77°F)
• Operating temperature: 5°C ÷ 40°C (41°F ÷ 104°F)
• Allowable relative humidity: <80%RH
• Storage temperature: -10°C ÷ 60°C (14°F ÷ 140°F)
• Storage humidity: <70%RH
• Max operating altitude: 2000m (6562ft)

7.3. Accessories

7.3.1. Accessories Provided

• Carrying bag
• Battery (not inserted)
• User manual

8. Service

8.1. Warranty Conditions

This instrument is warranted against material or manufacturing defects under general sales conditions. Defective parts may be replaced during the warranty period. Transport for returns to After-sales Service or Dealer is at the customer's charge, with prior agreement. Shipments must include a report stating the reason for return. Use original packaging; damage from non-original packaging is charged to the customer. The manufacturer is not responsible for injury to people or property damage.

The warranty does not cover:

• Repair/replacement of accessories and batteries.
• Repairs due to incorrect use or use with non-compatible appliances.
• Repairs due to improper packaging.
• Repairs by unauthorized personnel.
• Modifications without manufacturer's authorization.
• Use not specified in the manual.

Manual content reproduction requires manufacturer authorization. Products are patented; specifications and prices may change due to technological improvements.

8.2. Service

If the instrument malfunctions, check the battery first. If issues persist, verify operation according to the manual. For returns to After-sales Service or a Dealer, transport is at the customer's charge, with prior agreement. Shipments must include a report stating the reason for return. Use original packaging; damage from non-original packaging is charged to the customer.