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FT8 signal report Sent/Rcv consistent difference

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Andy - KU7T
Andy - KU7T Member ✭✭
edited October 2019 in FLEX-6000 Signature Series
I noticed for a while that I can hear better than I am being heard. I always thought, its likely because of a quiet location, a good radio (6600M) and maybe others running more power. Now, with FT8, I have real comparisons and can surely see a 5 - 10 db difference for most contacts.  I am running a full 100W into my radio. I know that others may run more than that, even for FT8, but probably not many.  My first action will be to check all coax connections. I am not sure how easy it is to measure the output power at the SteppIR, but I could measure power at the bottom of the antenna.  Any other suggestions how to troubleshoot this?

Answers

  • Duane_AC5AA
    Duane_AC5AA Member ✭✭✭
    edited September 2019
    Options
    Tell us more about your antenna system - antenna, feedline, any transmatch needed, etc.  That would help. 
  • Andy - KU7T
    Andy - KU7T Member ✭✭
    edited September 2019
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    The full coax length of LMR400 is about 160 feet long (to the tower and up). Between the radio and SteppIR DB18, I have these devices inline:

    - W2 2000W RF probe
    - polyphaser ligthning protector
    - 8 x 2 coax switch
    - PL-PL coax coupler at base of tower
    - SteppIR DB18 connection box on the antenna

    I realized, I have not made a lot of FT8 contacts on my other antennas. I will try this today. I have a DX engineering fan dipole, 40m vertical and 80 m vertical. These other antennas go through the same coax up the 8 x 2 switch. Maybe I can infer something from trying with these other antennas. Will report back.

    Thanks,
    Andy
    KU7T
  • Robert Lonn
    Robert Lonn Member ✭✭
    edited September 2019
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    Welcome to the world of Antennas, Propagation and Black Box Technology!! Basically anything can be proven and figured out,, but the variables are enormous.. However this is what makes Ham Radio so DAM interesting and fun!! 

    The key for most hams is having the right type of test equipment to evaluate everything... Once I found that after 2 weeks of research and the help of a silent key ham from 40 years ago, that the guy wires of my tower were screwing up my Hy Gain tribander..

    The SWR was OK but my Beam Pattern was corrupted!!! I had good signal reception but my TX outbound was not right??? He proved all this to me with a AN/PRM-10 Grid Dip meter!!! We installed insulators in the guy wires! I still have my PRM-10 and some spare ACORN tubes as this device puts out a whopping Oscillation signal, very powerful and puts my Millen 90651 to shame!! You just have to love this hobby!!

    Good Luck with your investigation!!

    Robert


  • John - AI4FR
    John - AI4FR Member ✭✭
    edited September 2019
    Options
    Lots of variables here. But since you are new at it, I'd start with the radio settings. How's the ALC meter looking, antenna gain or attenuation, RX bandwidth, etc. then work outwards. Do not assume that many folks are running 100 watts or less. The amount that are running amps at high power may just surprise you. Heck, I even see a difference in dB when running two slices off the same antenna. A good test bed is WSPR. Watch the following two sites for your call as well.

    https://hamspots.net/ft8/
    https://pskreporter.info/



  • George KF2T
    George KF2T Member ✭✭✭
    edited September 2019
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    Remember the reports you get in WSJT-X are not signal strength values. They are a signal to noise representation. Looking at your location and excellent installation, I’d venture to say you have much better receive capabilities than most other stations. With the bonus of DAX not requiring A/D conversion and the attendant degradation of received signals, your great installation, radio, and location really do put you ahead of the average Joe. Nice job!
  • Dave KØKQ
    Dave KØKQ Member
    edited September 2019
    Options
    Andy, I have the same thing.

    Very low noise location, excellent Flex receiver. When someone doesn't respond when their signal is strong, I feel for them with such poor receivers. 

    Never run more than 50 watts on FT8. The log is full of stations that have way stronger reports than they've given me.

    Unrelated, but  Gary Hinson ZL2iFB has written an excellent read for all FT8 ops:  
    ZL2iFB pdf guide. 

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