Eliminating noise on vlf

Discussion in 'The Low Bands - 630/2200 Meters - VLF' started by N4AEQ, Jul 3, 2019.

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  1. N4AEQ

    N4AEQ Ham Member QRZ Page

    I know it's summer and noise is bad now, but I have it all year long. I have several vlf receivers & use my 160m dipoles as a receiving antennas for 630 & 2200, they are on separate feedlines N/S and E/W. Noise it tolerable
    on 160m but starts to pickup at the AM band and increases as I drop. Years ago I could easily pickup LF AM brodcast stations from Europe in the winter, this past year noise was so bad I gave up. What can I do to fix this? Now For now I am interested in receive only antenna/setup.
     
  2. WA4ILH

    WA4ILH Subscriber QRZ Page

    Try looking into a magnetic loop receive antenna. DX Engineering has one for under $300.00. It is possible to build your own but special care must be taken to design and build the preamp for this type of antenna. BTW.....
    MF 300 KHz to 3,000 KHz
    LF 30 KHz to 300 KHz
    VLF 3 KHz to 30 KHz
    Tom WA4ILH
     
  3. WA4ILH

    WA4ILH Subscriber QRZ Page

    If you’re really interested in low noise antennas for the lower frequencies, you may consider picking up a copy of “Receiving Antennas for The Radio Amateur” by Eric Nichols, KL7AJ. Eric addresses a number of low noise antennas in an easy to ready style. Available from the ARRL book store. (no, I am not a salesman for KL7AJ or the ARRL)
    Tom WA4ILH
     
  4. AA5CT

    AA5CT Ham Member QRZ Page

    re: "I know it's summer and noise is bad now, but I have it all year long. "

    Are you living next to an electrical substation or an aluminum smelter?

    If no, then there might be hope for you, if you can find specific 'noise sources' in your neighborhood. The use of direction antennas (like a vertical rx loop) can provide some relief, since terrestrial ground-wave emanating sources can be nulled.
     
  5. 2E0ILY

    2E0ILY Ham Member QRZ Page

    Have a look at N1BUG site and his low noise vertical, it appears to work very well on LF, he receives me her in the UK on 137kHz WSPR2 and slow morse regularly. You also need a tight band pass filter and maybe a pre amp before the receiver, the BPF will help filter out of band noise. I use a Softrock Lite II and a Red Pitaya on LF and MF. The red Pitaya MUST have a BPF to do any good at all, and a small pre amp. With these it' excellent. My antenna for RX and TCX is my horizontal quad loop with the feeder window line strapped at ground level. resonating the antenna is also greatly beneficial even for RX ( a must for TX...). I use the same BPF as shown on N1BUG's site for his Softrock Lite RX.
     
  6. N4AEQ

    N4AEQ Ham Member QRZ Page

    Thanks for the post, I always recheck daily for new replies, n1bug site is very interesting. Sometimes finding information on making BPF and other items for these bands are hard to get, even less info on factory made items.
     
  7. KF6LXI

    KF6LXI Ham Member QRZ Page

    I have been a medium-wave DXer for many years and loop antennas greatly reduce the noise from power lines, etc. At a previous house which was being built I stapled some bell wire to the studs and ran the ends into outlet boxes. These loops were perpendicular to each other, After the drywall was installed, I wound a couple of toroids to convert the balanced loops to the unbalanced receiver input. At my new place I went to Home Depot, got 50 feet of RG-6 QS and some PVC pipe, made an unbalanced shielded loop of 10 feet long and 7.5 feet high and hung it from the side of my carport. It works fairly well, but of course it is non-rotatable. With a sensitive enough receiver it should work. Aim it in the direction you want to hear signals from.
     
  8. KL7AJ

    KL7AJ Ham Member QRZ Page

    Thank you, Tom! I was going to recommend it myself. HI!
    I am currently working with RSGB on the next edition of LF Today, which will explore other low noise methods, too. Alas, I can't give out too much information yet, but it will be good.
     
  9. WQ2H

    WQ2H QRZ Lifetime Member #214 Platinum Subscriber Life Member QRZ Page

    Hi Charles,

    If you're looking for receiving antennas for LF/MF - I've had good success with both the CCW active vertical and the L-400B vertical. The CCW preselector is also handy especially for MF in areas with broad band noise.

    Even though we live out "in the sticks" the LF noise floor here hovers between S4 and S9 so I often use a little attenuation, say 2-4db or so.

    Here's a shot of the CCW - I've switch it in full time for the Rx on the 630m WSPR. Good luck !

    73
    Jim, WQ2H / WK2XAH

    CCWs.jpg
     
  10. N4AEQ

    N4AEQ Ham Member QRZ Page

    Ok, Jim, thanks for the photo. It looks awful small for a LW or MW antenna, my ringo ranger for 2 meters is that tall I just dont understand how such a short physical antenna can perform at those wavelengths.
     

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