Re: RG6 Coaxial Cable - pwede ba ito gamitin sa VHF portable or base radio?

[magsy]

hindi ata pwede yan kasi ang HF / VHF / UHF & SSB radio ay gumagamit ng 50ohms coaxial cable at ang RG6 ay may 75ohms line impedance. RG6 at RG59 ay naka design para sa TV lines (75ohms). sa Radio naman RG58 ang ginagamit (50ohms).

baka masyado ng mataas ang SWR mo nakakasira din yun ng Final X'sistor ng Tx (pagmasyadong mataas ang SWR).

agree ako dyan...

[Simatar]

Mga kosa last year pa thread na to pero nakikisali na rin...

Ang tanong kasi kung pwede gamitin sa porta o base ang RG6...

Kung ifollow natin priciple e hindi "dapat" gamitin sa VHF tranceiver ung 75 ohms impedance cable tulad ng RG6, kasi tama mga master natin nagsabi na  50 ohms  dapat gamitin sa VHF.

PERO may mga kakilala ako na gumagamit ng 75 ohms cable for their VHF radios.

Bakit nila ginagamit? 
    ...kasi OK naman SWR reading pag check sa SWR meter,
    ...75 ohms ang available at hand.
    ... and take note sa performance wala sakit ng ulo. And sa radios nila wala naman abnormality...

So pwede pa rin. 

[dan.enriquez]

^^ iwan ko lang sir pero as engineering design hindi magandang practice yung sinasabi nyo..

gagana "OO" bakit naman hindi kahit siguro anong coax cable gagana dyan eh..

pero yung theory and practice dapat mong e consider..

[du1vss]

a lot of hams do not know that 75 ohms coaxial cable can be used as a transmission line in a 50 ohms transceiver and antenna. as stated above by GX, half wave line will repeat the impedance present at the input of the line(coaxial) to its output ,---so by cutting your rg-6 by multiple of half waves you will able to get a perfect match. compute for the halfwave length and please dont forget to include the velocity factor of your rg-6.  73 de dv1vss

[1-Lucio]

a lot of hams do not know that 75 ohms coaxial cable can be used as a transmission line in a 50 ohms transceiver and antenna. as stated above by GX, half wave line will repeat the impedance present at the input of the line(coaxial) to its output ,---so by cutting your rg-6 by multiple of half waves you will able to get a perfect match. compute for the halfwave length and please dont forget to include the velocity factor of your rg-6.  73 de dv1vss

bossing bigyan mo naman kami ng computation ng 75 ohm cable at ng 50 ohm cable para ma perpek ang match over 2m radio,  ganu ba kahaba ang standard kung me taas ang bahay mo ng 3 palapag halimbawa

[dacs]

you need to find the  velocity factor (vf) of the coaxial cable.  the wavelength is equal to (3x10^8)(vf)/frequency.  every multiple of half a wavelength exhibits the rated characteristic impedance of the cable at both end.  if, for example, you have a coaxial cable from your radio to the antenna with length of 7.5 meters and the half-wavelength for that cable at the operating frequency is 1.5 meters.  Then, 7.5 divided by 1.5 gives 5.  therefore, the cable length being used is a multiple of half a wavelength and will therefore exhibit the characteristic impedance of the cable at both ends.

on the other hand, if you have only 7.2 meter cable length and the half-wavelength for that cable at the operating frequency is 1.5 meters; then 7.2 divided by 1.5 gives a remainder of 1.2 meters.  It is this 1.2 meter remainder that will define the effective impedance of transmission line (i.e., the coaxial cable).  Between 0 and half a wavelength as remainder, the reactive component of the impedance is not zero and is therefore either inductive or capacitive.

The overall impedance matching work is a little more complex after that.

73s.


dv7ebq