| Author |
Message |
    
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 479
Registered: 10-2002
| | Posted on Thursday, February 18, 2016 - 2:17 pm: | 
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What is the added loss between 75 ohm coax to 50 ohm coax? At one time you mention there is an added loss to the use of 75 vrs 50 ohm. I do not remember nor can I find the amount of loss you had spoke of . I know for example the 75 ohm I have is a .4 db loss for 100 foot and the ca 400 is a .7 db loss for 100 foot. I know the amount of wattage loss between the two but I do not know the added loss by the use of the 75 ohm. I hope I explained this well enough to answer. |
Tech833
Moderator
Username: Tech833
Post Number: 2348
Registered: 8-2002
| | Posted on Saturday, February 27, 2016 - 2:44 pm: |
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The loss comes from the slight mismatch between the 50 ohm radio, the 75 ohm coax, and the 50 ohm antenna input.
Also, important to note that the 75 ohm TV coax is not designed to carry much RF current, it's designed for receiving only. It will get warm when using it to transmit, proportional to the amount of power being transmitted, which will distort the cheap foam insulation and change the characteristic impedance of the cable, furthering losses over time.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 481
Registered: 10-2002
| | Posted on Sunday, February 28, 2016 - 9:46 am: |
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I had no idea. I have been using it for year's now What I have is the 3/4 inch 750 75 ohm tv line with the semi solid aluminum shield that the main line tv company use. Thanks |
Tech833
Moderator
Username: Tech833
Post Number: 2351
Registered: 8-2002
| | Posted on Saturday, March 05, 2016 - 5:37 pm: |
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OK, that's different. That cable will handle the current of a CB transmitter, no problem.
There is still a slight mismatch at the radio and antenna ends of the cable, but not a lot.
Your radio 'Mythbuster' since 1998
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