1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

SWR flip flop with linear in line??

Discussion in 'CB Antennas' started by PA770, Aug 31, 2018.

  1. PA770

    PA770 W9WDX Member

    Joined:
    Jun 29, 2016
    Messages:
    569
    Likes Received:
    237
    I get 1.1 on 40 and 1.2 on 1 running barefoot with a 10w dk on my Anytone 5555.. with external SWR/Power meter.

    I hooked up an RM 203 and with about 35w dk when running I get 1.4-1.5 on channel 1 and a 1.5-1.6 on channel 40.



    This is with the 5555 turned down to 1.5w dk (no worries folks.lol) as not to pop the amp.

    Which to be me is wierd as far as the flipped SWR running without it.

    Antenna is A99 with 36' of LMR240.
     
    #1 PA770, Aug 31, 2018
    Last edited: Aug 31, 2018

  2. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

    Joined:
    Apr 23, 2018
    Messages:
    1,375
    Likes Received:
    1,020
    Is the jumper the same LMR240?

    Thinking impedance bump...which can make the antenna appear "longer" (lower SWR on longer wavelengths) due to that patch cord coax interrupts the otherwise continuous coax and matching network in the radio.

    Because you originally tuned the antenna with radio in line not with the amp in line too...

    Then "barrel connector" the patch cord to the coax to the antenna - like you removed the amp and installed the jumper in place and used the Barrel adaptor - then re-run test...

    Then for grins and giggles - swap the SWR meter location from the original test point in the coax line, to the other where you measured the amp instead...re-run test...(you do have to use the Barrel connector adapter to finish this test correctly for the same conditions to be made equal as if the amp was in line)
    .
     
    #2 Handy Andy, Aug 31, 2018
    Last edited: Aug 31, 2018
  3. PA770

    PA770 W9WDX Member

    Joined:
    Jun 29, 2016
    Messages:
    569
    Likes Received:
    237
    Actually I tested the radio SWR with the amp in line and just off.. its been setup same since I just put in last week when I put up the A99.

    I then kicked on the amp and got the skewed numbers..

    The jumpers haven't been moved, granted there not LMR-240 either.

    The meter is last on the run.

    I did radio-amp-meter-antenna.

    I may try moving the A99 rings abit with amp on and try to get it down.

    My silly butt played with rings a tiny bit when I got it in and setting up barefoot McKinley.. should have left rings alone from factory.
     
  4. w9cll

    w9cll W9WDX Amateur Radio Club Member

    Joined:
    Jan 19, 2013
    Messages:
    3,286
    Likes Received:
    1,915
    The SWR setting you quoted here are nothing to worry about. If it jumped to 2.0 with the amp on them I would worry. People worry too much about the SWR numbers, I consistently run between 1.5 and 2.
     
    357magnum and BJ radionut like this.
  5. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

    Joined:
    May 1, 2013
    Messages:
    2,866
    Likes Received:
    1,856
    SWR is one of the most misunderstood readings.
    You are tuning to a frequency, not a power level. If your antenna is that good with low watts don't worry. A lot of the increase in SWR with amps on is due to harmonics.
    Your figures with the KL-203 are pretty much what I see all of the time.
     
  6. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    916
    Likes Received:
    644
    If the antenna tunes up good with just the radio then the antenna is good. Really 1.4 or 1.5 isn't bad but it could be better. The amp might need some tuning on its input. Put the SWR meter between the radio and amp and see if some matching needs to be done. If the SWR is good there then you might have a problem with the antenna coax or connections. I had to do some work to my Texas Star 350 to get the SWR right, You can see what I did here:
    https://www.worldwidedx.com/threads/texas-star-dx-350-hdv-input-swr.230089/#post-627003
    Chris
     
    357magnum and PA770 like this.
  7. PA770

    PA770 W9WDX Member

    Joined:
    Jun 29, 2016
    Messages:
    569
    Likes Received:
    237
    My concern was the big less than 1.5 note with the amp, and most amps..

    I was entertaining upgrading to a RM503 or RM7505 (new model)

    Of course they are all RM so worrying might be moot.
     
  8. PA770

    PA770 W9WDX Member

    Joined:
    Jun 29, 2016
    Messages:
    569
    Likes Received:
    237
    I might try moving the meter tonight in between radio and amp as it's pouring here.. ain't going on ladder in rain..
     
  9. Road Squawker

    Road Squawker Sr. Member

    Joined:
    Jan 19, 2011
    Messages:
    1,482
    Likes Received:
    811
    Thats because the transistorized amp is producing wide banded RF.
    ... and the antenna is reflecting the RF that is not @ or near) the resonant frequency.

    The amp is either poorly designed or is being overdriven
     
  10. Dmans

    Dmans Well-Known Member

    Joined:
    Jan 22, 2017
    Messages:
    343
    Likes Received:
    213
    K3ACZ,
    35 watt forward power with a 1.5:1 SWR calculates to a 1.5 watt reflected power. Nothing to worry about and won’t be noticed by anyone on the receiving end.

    As Shadetree mentioned, it could be tuned lower inside the amp with a tuned input circuit (and would quite possibly require a tunable output circuit) but the question remains-
    Is the juice worth the squeeze?

    73’s
    David
     
  11. PA770

    PA770 W9WDX Member

    Joined:
    Jun 29, 2016
    Messages:
    569
    Likes Received:
    237
    So if I switch to a 503 pushing 200w AM with swing and it also calls for a 1-6w dk, and less than 1.5-1 SWR I should be good also??

    Also I noticed when using SSB my SWR is totally wacky with modulation.. is that normal?
     
  12. PA770

    PA770 W9WDX Member

    Joined:
    Jun 29, 2016
    Messages:
    569
    Likes Received:
    237
    Just the radio is either 1-1 or 1-1.2.. so that's good IMO..

    If testing with the meter between the radio and amp what if I get the same 1.5 or so with the amp on?? (Hoping not obviously)
     
  13. Dmans

    Dmans Well-Known Member

    Joined:
    Jan 22, 2017
    Messages:
    343
    Likes Received:
    213
    K3ACZ,
    With the meter between your transmitter and amp you will almost certainly see a greater SWR than straight to the antenna. The amp is an “impedance bump” to your 50 ohm (perfect SWR) antenna system. (Antenna system being everything between your transmitter and antenna. All SO239’s, PL259’s, coax cables, antenna, antenna adjustment rings, antenna grounds......)
    The amp could be made perfect so that there is a perfect 50 ohm load to the transmitter. That perfect load may get you an additional 6 or 7 watts output. Hardly seems worth the trouble and not noticeable to anyone.

    You can’t check your SWR on SSB unless you can calibrate your forward power meter then check your reflected power under the exact same conditions. Check it on AM with a dead key with no modulation.

    If your SWR reading between your transmitter and amp is greater than 2.1 and your transmitter is transistorized finals ( vs. tube finals) you may want to improve the input match of the amp to protect your output transistors of your transmitter.

    73’s
    David
     
    PA770 likes this.
  14. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    916
    Likes Received:
    644
    If there is like 2:1 or higher between radio and amp it will cause the amp to generate rf that is off frequency which causes the high SWR.
     
    PA770 likes this.
  15. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    916
    Likes Received:
    644
    Do you have the SWR meter at the antenna?
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!