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Triplett CableRater, Инструкция по эксплуатации

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23

Figure 10

Amplifier and 16 Way Splitter

The amplifier must have the appropriate Gain to place the signal levels in the

appropriate range. A level towards the top end of the range is desired. Amplifiers

are available in several Gains, or in Variable Gain. Typical Gains are 10dB, 12dB,

15dB, or 20dB. A 15dB amplifier would be a good choice .  This would raise the

level at each outlet to about +7 to +9dBmV.

To use the CableRater to test this system, first without the amplifier.. connect

the Transmitter to the input of the 16 way splitter. Then, connect the Receiver to

each outlet and measure the Loss. Its expected to read about -16dB. Next add

the amplifier to the circuit, connect the Transmitter to the input of the amplifier,

and measure the Loss at each outlet. It should read about -1dB.

So, if +10dBmV is applied to the input of the amplifier, about +9dBmV can be

expected at each outlet.

9.8.5 Long Cable Runs

If the length of the coaxial cable run exceeds about 50 feet, from the Cable

Provider’s connection on the outside of the building to the inside TV outlet, the

coax’s Loss must be considered. There may, or may not be splitters or amplifi-

ers in the line. The total length of the cable is what’s important.

Figure 6 shows that the Loss for 100 feet of RG-59 at 60MHz is about 2.4dB.

This amount of Loss is usually tolerable. However, the 900MHz Loss of 10.2dB

Содержание CableRater

Страница 1: ...CableRater dB Loss Meter Instruction Manual TRIPLETT 84 875 6 08 ...

Страница 2: ...een the Transmitter and Receiver measured with the press of a button The CableRater is an invaluable tool for verifying the design of a Cable TV distri bution system prior to the connection of any Cable TV services It can be used to troubleshoot a newly installed distribution system prior to or following the application of drywall Before the introduction of the CableRater it was usually necessary ...

Страница 3: ...vice is connected 3 4 CableRater Transmitter simulates frequency and level of TV channel 3 3 5 Large backlit Blue EL digital display for accurate low light testing 3 6 Lightweight and convenient 3 7 Locking power switch on the Transmitter prevents accidental turn on 3 8 Battery Test in Transmitter and Receiver 3 9 Efficient Transmitter design permits hours of tests without replacing battery 3 10 R...

Страница 4: ...30 dBmV 50dBmV max 5 2 2 Input Frequency Approx 61 25MHz Channel 3 5 2 3 Input Impedance Approx 75 Ohms 5 2 4 Loss Gain Accuracy Approx 2dB 5 2 5 Loss Gain dB Resolution 0 1dB 5 2 6 Display 1 high High Contrast LCD w backlight 5 2 7 Backlight Blue Electro Luminescent operable by separate pushbutton 5 2 8 Auto Shut Off 4 settings approx 1 to 5 min after last signal is measured 5 2 9 Battery Require...

Страница 5: ...ell Phone towers Pager towers Ham Radio operators Microwave links etc A distribution system that is in proper operating condition shields out these over the air signals so they don t interfere with the cable TV signals However a distribution system that has faults for example a shield s on a coaxial cable is open can allow over the air signals into the system This is called ingress Ingress will of...

Страница 6: ...6 6 TRANSMITTER FRONT PANEL UNLOCK C B A D E Figure 1 A Battery Test LED B Unlock Button C ON OFF Power Switch D Output Connector E Zero Calibrate Knob ...

Страница 7: ...CEIVER FRONT PANEL C B A E D F G Figure 2 A LCD Display with Backlight B Low Battery Annunciator C Auto Power Off APO Annunciator D Under Range Annunciator E Backlight Button F Power Button G Input Connector ...

Страница 8: ...er snuggly and is sometimes difficult to remove 8 2 3 If changing the settings of the APO refer to Figure 3 to see the location of the jumpers that control the settings A small pair of pliers or tweezers may be helpful to move the jumpers JP4 JP3 JP2 JP1 Figure 3 There are 4 locations for the jumpers JP1 JP2 JP3 and JP4 Only 3 jumpers are needed The product is initially set to the APO mode with th...

Страница 9: ...ss the UNLOCK button while moving the ON OFF switch from the OFF to the ON position Release the UNLOCK button When the switch is moved to the OFF position it will lock in this position requiring the user to again press the UNLOCK button to turn the switch ON 9 1 2 BATTERY TEST Indicator The BATTERY TEST indicator is a green LED Light Emitting Diode that flashes periodically when the battery is goo...

Страница 10: ... first turned On the Receiver s LCD display may momentarily show ran dom numbers or symbols but within a few seconds the display should indicate the correct level When turned Off the Receiver goes into a low power standby mode waiting for the next button press It can remain in this mode for months without depleting the battery If the Backlight is turned On when the Receiver is turned Off the Backl...

Страница 11: ...ng tested is connected to the Input of the Receiver This often requires the use of a patch cable 9 2 4 LCD Display The LCD display reads Gain or Loss in dB deciBels It also provides informa tion about the battery condition the APO mode and whether an adequate test signal is being received 9 2 4 1 Underrange Indication If no test signal or inadequate test signal is applied to the Receiver the LCD d...

Страница 12: ...ature is activated see 8 2 APO will appear in the display The APO feature allows the product to remain on as long as a signal is being measured If a signal is not being measured the product will turn itself off after the preset timeout duration see 8 2 3 The timeout duration is reset to its full interval whenever a signal is measured 9 2 4 4 Low Battery Indication If appears in the display the bat...

Страница 13: ...r stretched excessively can develop a break in the shield Replace the cable If the over the air signals are especially strong in the vicinity of the test ingress can occur if the ends of the cable are left unterminated The small center con ductor of the cable acts as an antenna picking up over the air signals There are terminations that screw onto unused F connectors preventing ingress and re flec...

Страница 14: ...or does not flash replace the depleted battery with a fresh battery Turn On the Receiver by pressing and releasing the Meter Push On Off button If desired turn On the Backlight by pressing and releasing the Backlight Push On Off button Observe the LCD display The Low Battery symbol must not be displayed If it is replace the de pleted battery with a fresh battery APO may or may not be displayed dep...

Страница 15: ...itter Test If the user suspects the Transmitter is not working properly it can be tested by connecting it to the antenna input of a television set to Channel 3 The TV should display a blank screen no snow Different TV s will display a blank screen differently Common displays are a white gray black or blue screen The CableRater Transmitter does not produce a sound signal so the TV may pro duce no s...

Страница 16: ...ft Cables less than 50 ft long should have Losses of less than 1dB To check the Loss of a cable first Calibrate the Transmitter as described in 9 4 then connect one end of the cable to be tested to the Transmitter Output and the other end of the same cable to the Receiver Input similar to Figure 5 but using the cable you are testing instead of the patch cable Press the Meter button on the Receiver...

Страница 17: ...B of error in the measurement often less than a few tenths of a dB of error If a measurement indicates that several cables of slightly different length for example 10 11 and 12ft show losses that seem contradictory to their length the likely cause is Standing Waves This is a well documented phenomenon and not a reason for concern i e the cables are not bad 9 6 Testing Loss in a Splitter Splitters ...

Страница 18: ...e that the smallest splitter a 2 way has more loss than 100 ft of cable at 60MHz UNLOCK Figure 8 2 Way Splitter with a termination on the unused output being tested Note Some splitters have different losses on their outputs This is most commonly seen on 3 way splitters These splitters are usually marked with the expected loss for each output 9 7 Testing Amplifier Gain There are many types of ampli...

Страница 19: ... 9 Press the Meter button on the Receiver and read the Gain on the LCD display UNLOCK Figure 9 Transmitter Amplifier and Receiver The maximum output level that an amplifier can produce must be considered Most common amplifiers cannot produce output levels exceeding about 40dBmV Since the output level of the CableRater Transmitter is 10dBmV an amplifier with a 30dB gain connected directly to the Tr...

Страница 20: ... is incorporated into the cable distribution system Some amplifiers can become unstable when the CableRater Receiver is con nected to their output The CableRater Receiver does not have a wideband 75 Ohm input impedance 75 Ohms is the standard impedance of a cable TV distri bution system The CableRater Receiver uses a narrowband 75 Ohm input impedance This sometimes causes an amplifier to oscillate...

Страница 21: ...e simpler the system will be to implement It is also important to know the typical signal level measured at the connection to the building that is acceptable to your Cable TV Provider In many localities it is in the 10dBmV to 15dBmV range 9 8 2 How much Loss is acceptable If the Cable TV Provider typically delivers a 14dBmV signal to the premises and a minimum of 5dBmV is desired all outlets the m...

Страница 22: ...nstalling a splitter with more outputs will reduce the signal level on each output Alternately an in line attenuator can be used to reduce the signal level 9 8 4 Is an amplifier needed If a large number of outlets are to be used a large splitter like a 16 way or more may be needed Use of a large splitter may reduce the signal level below the minimum acceptable level at each outlet For example if t...

Страница 23: ...d measure the Loss Its expected to read about 16dB Next add the amplifier to the circuit connect the Transmitter to the input of the amplifier and measure the Loss at each outlet It should read about 1dB So if 10dBmV is applied to the input of the amplifier about 9dBmV can be expected at each outlet 9 8 5 Long Cable Runs If the length of the coaxial cable run exceeds about 50 feet from the Cable P...

Страница 24: ...sator for proper use and adjustment 9 9 Identifying Cables When a large number of cables have been installed and are unmarked the CableRater can aid in identifying the cables The typical distribution system lay out has the ends of all of the cables routed to a central location and the far ends of these cables located in the areas where televisions will be connected Calibrate the Transmitter as des...

Страница 25: ...e in selectivity and the reference level the CableRater usually reads about 6 to 8dB lower than the actual level of TV chan nel 3 For example if the CableRater Receiver reads 0 0dB when connected to an operating cable TV system the level of Channel 3 is probably about 6 to 8dBmV There are many variables that can affect the reading so it should be understood that the reading is a guestimate It is n...

Страница 26: ...TURN INSTRUCTIONS In the unlikely event that you must return your Triplett equipment for repair the following steps must be taken 1 Call 1 800 TRIPLETT to obtain a Return Material Authorization RMA number from Customer Service 2 Enclose a copy of the original sales receipt showing date of purchase 3 Clearly print the RMA number on the outside of the shipping container 4 Return to Jewell Instrument...

Страница 27: ...e provisions of this warranty contact Triplett Jewell Instruments Customer Service Department for a Return Authorization Number RMA and return instructions No returned product will be accepted without an RMA number Upon our inspection of the product we will advise you as to the disposition of your claim ALL WARRANTIES IMPLIED BY LAW ARE HEREBY LIMITED TO A PERIOD OF ONE YEAR FROM DATE OF PURCHASE ...

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