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RNE678/125 - 04 : 2005 Cable Type 125
   
Testing Specification
     
     
    Last Updated 14th September 2005
     
   

1.          General....... 3

2.          Mechanical Specification... 3

3.          Cable Measuring  3

4.          Testing (Electrical)...... 3

4.1           Conductor Resistance 3

4.2            Regularity of Impedance 4

4.3            Longitudinal Loss (Attenuation)         4

4.4            Return Loss 4

4.5           Capacitance 4

4.6           Relative Propagation Velocity      4

4.7           Characteristic Impedance 5

4.8            Static Bend Test 5

4.9           Multiple Bending Test 5

4.10              Screening Attenuation              5

4.11              Flexing              6

4.12              Crush Resistance              6

BENCHMARK SUMMARY: RNE678/125-03 2004.………………APPENDIX
1.        General

This specification defines the pass/fail criteria for the testing of cable type 125, and references the relevant sections of BS EN 50117-1: 1997 where appropriate. The methods of BS EN 50117-6: 1997 are used as appropriate.

 

All details, where applicable, will be recorded on QMF17d: Cable Testing Result Sheet. When a cable fails any section, the details of the failure will be fully recorded.

 

High quality connectors are to be used to test the cable as required throughout this procedure, referencing the correct method of connection in the VHF/UHF Handbook.

2.        Mechanical Specification

The mechanical specifications for the cable as follows:

 

Inner Conductor

:

To be copper

Diameter Of Inner Conductor

:

1.25 +/- 0.03mm

Outer Braid / Tape

:

No contact between dissimilar metals

External Diameter Of Sheath

:

8.0 +/- 0.4mm

Bending Radius

:

50mm

Flexing Radius

:

100mm

3.        Cable Measuring

Physically measure and cut 100m(+/-25cm), 30m(+/-6cm) and 3m(+/-3cm) from the cable to be tested using a tape measure, when required. Once measured, put onto reels as required for the tests to be carried out.

4.        Testing (Electrical)

Carry out the following tests with 100m of cable on the drum

4.1          Conductor Resistance

(Reference BS EN 50117-1: 1997 Section 11.1)

 

Calculate the DC resistance of the cable under test, at 20 ºC, of both the inner and outer conductors.

 

Measure the volt drop across the inner and outer conductors and convert the reading to W/km.

 

Express the result to the standard temperature of 20 ºC using BS EN 50117-1: 1997 Section 11.1.5 equation (7).

 

The DC resistance of the inner conductor should be < 15 W/km.

 

The DC resistance of the outer conductor should be < 13.5 W/km.

 

4.2           Regularity of Impedance

(Reference BS EN 50117-1: 1997 Section 11.9)

 

Using a TDR, enter the velocity ratio of the cable under test as specified by the manufacturer into the TDR, and observe the cable regularity of impedance.

 

Regularity of Impedance should be < 1% throughout the test specimen.

4.3           Longitudinal Loss (Attenuation)

(Reference BS EN 50117-1: 1997 Section 11.8)

 

The attenuation of the cable under test should meet the following:

 

5 MHz

:

< 1.5 dB/100m

50 MHz

:

< 3.5 dB/100m

100 MHz

:

< 5.0 dB/100m

200 MHz

:

< 7.5 dB/100m

460 MHz

:

< 11.5 dB/100m

860 MHz

:

< 15.5 dB/100m

1000 MHz

:

< 17.0 dB/100m

1750 MHz

:

< 22.8 dB/100m

2150 MHz

:

< 26.0 dB/100m

4.4           Return Loss

(Reference BS EN 50117-1: 1997 Section 11.6)

 

The return loss of the cable under test should meet the following:

 

5 - 30 MHz

:

> 23 dB

30 - 470 MHz

:

> 23 dB

470 - 862 MHz

:

> 20 dB

862 - 2150 MHz

:

> 18 dB

 

In each frequency band, 3 peak return loss values up to 4dB lower than the specified limit are permissible.

 

Carry out the following tests with 30m of cable cut from the drum

4.5          Capacitance

Measure the capacitance of the cable under test using a capacitance meter and convert the reading to give pF/m.

4.6          Relative Propagation Velocity

(Reference BS EN 50117-1: 1997 Section 11.7)

 

Calculate the required values using BS EN 50117-1: 1997 Section11.7.4 equation (15) & (17).

 

Express the final value using BS EN 50117-1: 1997 Section 11.7.5 equation (18).

4.7          Characteristic Impedance

(Reference BS EN 50117-1: 1997 Section 11.5)

 

Using the values obtained in section 4.6 above, and capacitance value obtained in section 4.5 above. Apply the values using BS EN 50117-1: 1997 Section 11.5.1.2 equation (9) to calculate the impedance of the cable under test.

 

The Characteristic Impedance should be 75W +/- 3W.

 

Carry out the following tests using new cable from the drum

4.8           Static Bend Test

(Reference BS EN 50117-1: 1997 Section 10.2.4)

 

Using a 20m (minimum) piece of the cable under test, wrap a section 180º around a 100mm diameter mandrel - ensuring the cable touches all the required parts of the mandrel.

 

Using a TDR, ensure that the regularity of impedance is < 1%.

 

After testing, there should be no cracks, or breaks in the dielectric, metallic elements or sheath.

4.9          Multiple Bending Test

(Reference BS EN 50117-1: 1997 Section 10.2.1)

 

Using a 10m (minimum) piece of the cable under test, bend a section 90º around the 100mm diameter mandrel, then straighten and bend again 3 times. Wind the same section of cable three turns around the same mandrel. Ensure the cable touches all the required parts of the mandrel for these tests.

 

Using a TDR, ensure that the regularity of impedance is < 1%.

 

After testing, there should be no cracks, or breaks in the dielectric, metallic elements or sheath.

 

Carry out the following tests using a new 3m section of cable.

4.10          Screening Attenuation

(Reference BS EN 50117-1: 1997 Section 11.10)

 

Using the formula specified in BS EN 50117-1: 1997 Section 11.10.6 equation (31), the result +6dB of the cable under test should meet the following attenuation levels :

 

30 - 470 MHz

:

> 75 dB

470 - 1000 MHz

:

> 75 dB

1000 - 2150 MHz

:

> 65 dB

Carry out the following tests using 15m section of new cable

4.11          Flexing

(Reference BS EN 50117-1: 1997 Section 10.2.2)

 

Mark the middle 10m of the cable under test as the test area, and pull the cable through the      200mm diameter pulleys backwards and forwards 5 times, with a force of 10 to 20 N, at a rate of not less than 1m/minute.

 

Using a TDR, ensure that the regularity of impedance is < 1%.

 

Re-check the screening attenuation on a 3m length of the 10m of cable tested using the set up in Section 4.10, and the formula specified in BS EN 50117-1: 1997 Section 11.10.6 equation (31), the result +6dB of the cable under test should meet the following attenuation levels :

 

30 - 470 MHz

:

> 65 dB

470 - 1000 MHz

:

> 65 dB

1000 - 2150 MHz

:

> 65 dB

 

After testing, there should be no cracks, or breaks in the dielectric, metallic elements or sheath.

4.12          Crush Resistance

(Reference BS EN 50117-1: 1997 Section 10.4)

 

Using a TDR and a torque wrench set to 13.6Nm, ensure the cable has no lateral movement and apply a crush load to the cable for 2 minutes.

 

Ensure that the regularity of impedance is < 1% and record any magnitude variations.

 

 

Benchmark Summary : RNE678/125-04 2005 Cable Type 125

 

 

STANDARD

:

 

BS EN50117-1: 1997 Coaxial Cables used in cabled distribution networks

Sections

:

 

10.2.1, 10.2.2 , 10.2.4 , 10.4 , 11.1 , 11.5 , 11.6 , 11.7 , 11.8 , 11.9 , 11.10

 

 

MECHANICAL SPECIFICATION

 

 

Inner Conductor

:

Copper

 

Diameter Of Inner Conductor

:

1.25 +/- 0.03mm

 

Outer Braid/Tape

:

No Contact Between Dissimilar Metals

 

External Diameter over Sheath

:

8.0 +/- 0.4mm

 

Bending Radius

:

50 mm

 

Flexing Radius

:

100 mm

 

 

ELECTRICAL SPECIFICATION

 

 

Nominal Impedance

:

75 W   +/-  3 W

 

DC Resistance (20° C)

:

Inner  < 15 W/km

Outer < 13.5 W/km

 

Attenuation :

 

 

 

5  MHz

:

<   1.5  dB / 100 m

 

50  MHz

:

<   3.5  dB / 100 m

 

100  MHz

:

<   5.0  dB / 100 m

 

200  MHz

:

<   7.5  dB / 100 m

 

460  MHz

:

< 11.5  dB / 100 m

 

860  MHz

:

< 15.5  dB / 100 m

 

1000 MHz

:

< 17.0  dB / 100 m

 

1750 MHz

:

< 22.0  dB / 100 m

 

2150 MHz

:

< 26.0  dB / 100 m

 

 

 

 

 

Return Loss :

 

 

 

5 - 30 MHz

:

> 23     dB

 

30 - 470 MHz

:

> 23     dB

 

470 - 862 MHz

:

> 20     dB

 

862 - 2150 MHz

:

> 18     dB

 

 

 

 

 

Screening Attenuation :

 

 

 

30 - 470 MHz

:

> 75     dB

 

470 - 1000 MHz

:

> 75     dB

 

1000 - 2150 MHz

:

> 65     dB

 

 

 

 

 

Screening Attenuation following Flexing Test :

 

30 - 470 MHz

:

> 65     dB