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S7 to S9 noise - bands closed or me?

Discussion in 'QRP Corner' started by N1KTJ, May 7, 2016.

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  1. N1KTJ

    N1KTJ Ham Member QRZ Page

    yes, that's my next test in a few days.

    Think I should also do a screen capture on JT65 screen (JT65 does work some) just to show what the resident noise is on each bands in the waterfall. good reference for others I hope.
    K6CLS likes this.
  2. N1KTJ

    N1KTJ Ham Member QRZ Page


    my JT65 spectrum on 20M. Yes obviously its working. But this is with an S7 to S8 noise level constant.
  3. K8JD

    K8JD Ham Member QRZ Page

    I would take a portable radio on AM and walk around the area and see if the noise peaks near utility poles other apartments or industrial buildings.
  4. WA7PRC

    WA7PRC Ham Member QRZ Page

    One word: mobile.
  5. N1KTJ

    N1KTJ Ham Member QRZ Page

  6. K7MEM

    K7MEM Ham Member QRZ Page

    While it seems to be a good product, the question is, do you have feed line radiation? If you do, this product might help. But I don't think that is your issue.

    As everyone else indicated, its often a matter of location, location, location. I live in a very rural area and with my trap dipole my S-Meter doesn't budge on any band, unless there is a signal there. However, in the late summer (monsoon season), when the storms start coming in, the trap dipole starts picking up some noise. Usually around S-2 or S-3. But during that same time, my vertical (5BTV) gets such extreme static, that I can see and hear the voltage discharging across the gap between the coax connector's center conductor and the shield. One summer, there was so much built up static that the 80 Meter resonator exploded. But during the rest of the year, the vertical works great.

    I wish I had a solution to your problem, but I don't. No matter where you live, there are some situations that you just have to work with as best you can.
  7. K8JD

    K8JD Ham Member QRZ Page

    It looks like your noise is all man made local trouble. You have to do some serious legwork to try to find the source(s).
    BUT, My biggest problem is lightning noise from near and far away on the lower bands at night.
    It comes every spring and lasts untill autumn. Not much you can do except use a narrow filter on CW. I have heard that some of the DIGI modes work better in a noisy situation.
    Even with S7-9 lightning crashes coming thru I managed to work a Florida station on 60M CW last night with very good copy. Well over 1000 miles !
    There IS Hope :D
  8. AI6KX

    AI6KX Ham Member QRZ Page

    I've resigned myself to having S9 noise on 40 meters 365/24/7. I've tried feedline chokes, turning off power sources including my solar system, hunting around the neighborhood with a portable SW receiver, and even listened one day when the power was cut for a half a block for repairs. There is a broadband source within a mile that I can't locate, and it makes a mess from about 5 to 10 megahertz. So I work CW on the low end of the band, with all RX filters cranked down. That's OK with me since the shortened dipole is pretty narrowband anyway.

    I'm going to try reorienting the dipole in a few days, but I don't have high hopes. Luckily the noise on 20 meters is only S5 or so, and 15 and 17 are nice and quiet.


  9. K7TRF

    K7TRF Premium Subscriber QRZ Page

    In your situation I'd strongly recommend adding either a shunt inductor or high value dissipation resistor across your 5BTV feed point to create a DC path to ground to gracefully discharge static buildup on the antenna.

    You can either use something like a 1 Mohm MOX resistor in the 3W to 5W range or a simple shunt inductor in the range of several tens of uH or more to provide a DC discharge path without altering the antenna tuning or efficiency.

    If you go the inductor route just make sure it's big enough (in uH or mH) that it presents a large admittance at the operating frequency such that the antenna tuning isn't impacted. For instance at say 3.5 MHz if you use a 25 uH shunt inductor it will provide roughly 550 ohms inductive reactance across the feed point which is a very high impedance shunt path on 80 meters and will have virtually no impact on antenna tuning so you get the DC discharge path without creating antenna tuning or power loss issues. A high value resistor does basically the same thing by discharging static DC buildup without impacting antenna tuning. Neither of these will do a thing for actual lightning strikes but they can definitely help by discharging static buildup on your antennas and help protect sensitive receiver front ends.

  10. AI6KX

    AI6KX Ham Member QRZ Page

    Just when I get ready to pull the big switch for a few weeks, everything changes. Tonight the noise on 40 is the lowest it's been in months. I don't run QRP on 40 but DX conditions for 100 watts are A-ok. QRP is FB on 15 and 17 now too.

    Tomorrow I'm raising my 4-band vertical groundplane another 25 feet, to keep the new tower from getting lonely until I get a beam on it.

    Steve in Okinawa

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