Different Coax and SWR Question

Discussion in 'CB Radio Forum' started by Rooster73, Jan 31, 2010.

  1. Rooster73

    Rooster73 Bobtail Member

    23
    16
    Dec 9, 2008
    0
    Buddy of mine just upgraded his coax to RG-8x.

    Will he need to have his SWRs rechecked?

    Does changing coax cable flirt with SWRs?
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0
    USING 50 OHM COAX like RG-8X should match very well ( under 1.5:1 )
    MANY CBers CUT COAX to tune a antenna when it's the antenna that needs to be tuned to the coax since the coax is already at 50 ohms.

    All you do with this coax cutting is trick the SWR meter.
     
  4. Rooster73

    Rooster73 Bobtail Member

    23
    16
    Dec 9, 2008
    0
    The antenna was previously tuned with a cheaper 50 Ohm 18' cable.

    He upgraded the cable quality and is still 18' in lenght.

    He does not own a swr meter, so that means he would have to visit his local shop to have it checked and there might be a small fee behind that visit.
     
  5. WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0

    IF he was using 50 ohm coax ( rg-58 rg-8x ) lengh is no factor in SWR what you are looking at is the VOLTAGE point of a swr caused by the antenns.

    If you put a 50 ohm load on the antenna end of that same coax you will
    read no swr no matter how long it is ...... and a antenna should be little in diffrence ....

    TO MATCH you would need a 75 ohm line and you cut it for the match this is done with phased antennas since two 50 ohm antennas are 25 ohms to a feed line .....
     
  6. Rooster73

    Rooster73 Bobtail Member

    23
    16
    Dec 9, 2008
    0
    Ok, just wanted to make sure before he keys down on it.

    He has no interest in a chance of burning up his "pride and joy" of a radio.

    Thanks WA4GCH.
     
  7. WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0
    YES SIR !!!!!!!

    FINALS ARE NOT CHEAP !

    My FT-100D finals are 300 bucks and thats just the parts ..... I baby that radio.
    My 160 watt 2 meter linear finals are $100 and YES I blew them but that was because of VERY BAD design of the amp The amp has a problem with FINAL FAILURES thanks the MFJ .....

    AND ON TOP OF THIS SMT parts are a nightmare to replace.... most amps on VHF/UHF use chipcaps and other mico parts ... way too small for my old eyes .....
     
  8. WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0
    ft100d and a micro ht VX-2
     

    Attached Files:

  9. Rooster73

    Rooster73 Bobtail Member

    23
    16
    Dec 9, 2008
    0
    With my question already being answered above, then it is safe to assume that one could screw the swr meter directly to the antenna to tune it, as opposed to hooking it up at the radio end of the RG-8x. Right?
     
  10. WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0

    YES YOU CAN HOWEVER even if you have 50 foot of coax tuneing it for min on ch 20 will work just as well.
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.