I hope I didn't damage the ionsphere

Discussion in 'Ham Radio Discussions' started by W4KJG, Jul 14, 2021.

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  1. W4KJG

    W4KJG Subscriber QRZ Page

    I've mostly been without a reasonable HF transmitting setup for almost a year. Last October we sold our WV farm and our NC beach home. We moved into town onto about a 1/4 acre lot that isn't in an HOA.

    Overall, it sure has had an effect on my on-air activities and experiments. I only get to spend a little bit of time with my ham equipment every couple of days.

    Over the past couple of months I've been doing a lot of measurements, clipping, snipping, winding/rewinding transformers, etc., to optimize my very non-perfect, non-resonant, end-fed inverted-L wire antenna. The vertical portion is about 35 feet long. The horizontal part is mostly about 35 feet above ground level. I finally stopped clipping/snipping at a total of 53 feet of wire with a combination of twelve 6 to 60 foot radials about 1 to 3 feet above ground. Temporary electric push-in fence posts hold the wires off the ground. The radials are made from 4-conductor telephone wire, with each conductor cut to a different length.

    I used a lot of powdered iron and ferrite toroid cores from about 1 inch to 2-1/2 inches in diameter. My toroids all came from Fair Rite, MicroMetals, and Amidon.

    I finally settled on a Fair Rite FT-240-43 core with seven tri-filar windings connected as a 9:1 UnUn. Four to 6 and 8 to 11 turns did not provide the same results. Smaller cores didn't provide the same performance. Their inductance and transformers seemed quite close. I was particularly surprised at the differences between core sizes, even though the same mix cores presented the same basic inductance and the same transformation ratio over equivalent frequency ranges. Type 43 mix was slightly better than type-60 mix over 3.5 to 29 MHz.

    I settled on an approximately 53 foot long piece of #14 multistrand insulated wire, a variety of above ground radials ranging from about 6' to 60', and lots of winding and rewinding of different UnUns on a variety of sizes and materials made by Fair Rite and MicroMetals.

    When I measured the feedpoint last night, it was mostly R=30 to 70 Ohms, and j+/- 15 Ohms, or less on 80/75, 40, 20, 15 and 10 meters. 30 meters looked pretty good too.

    FT-8 on ten meters was pretty active this morning. I made a few contacts. I switched to WSPR. Nothing! It was pretty much the same on 15 meters. But 40 and 20 WSPR and FT8 were crazy.

    I didn't get back to the shack until about 7:00 PM this evening. On 40 and 20 I started out with 5 watts on FT8. Most of the reports were coming back at -10 dB S/N to +10 dB S/N.

    I dropped to 1 watt on each band. The signal reports were about the same as 5 watts.

    I can'r reasonably measure RF power at the feedpoint below 0.5 Watts, but I was still making good contacts at about 0.5 W on 40 and 20 meters.

    Maybe it was just propagation. Or, maybe, my antenna is really working. Maybe I can find a way to better describe what I did. For now it has all been only non-scientific experimenting. It was optimized by empirical observations. I don't think what I have is reproducible in another location, maybe not even 50 feet away.

    We did get over 2 inches of rain after last night's measurements. Nothing changed significantly overnight.
    Last edited: Jul 14, 2021
    N5AL, N0TZU, N1VAU and 2 others like this.
  2. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    So using my new broadcast tube and a cast off substation transformer from the New Your Subway system, I can now ionize my own layer, thereby creating DX conditions whenever I want.:D

    My 500K amp tube.jpg
    Last edited: Jul 14, 2021
    WD4ELG, WD8T, N5AL and 4 others like this.
  3. WN1MB

    WN1MB Ham Member QRZ Page

    It certainly appears you're on to something that works! That's great.

    Now there's a crossroads on the horizon: further analyze, model, modify, tinker, optimize ... or ... leave well enough alone and just play radio.
    W4KJG likes this.
  4. W4KJG

    W4KJG Subscriber QRZ Page

    That thing looks impressive. It probably could set the ionosphere on fire.

    When I was in college in the 1960s I worked for two competing AM stations, their TV stations, and a separate FM station.

    My favorite was an early 1940s RCA 5 kW transmitter. It used a pair of 892R tubes for the modulators, and one 892R as the 5 kW final amplifier.

    I don't remember how many RCA 892R tube sets we had, but about every three months I was supposed to take the modulator and final amplifier tubes out and replace them with one of the sets we kept in rotating storage. They had handles on their heat sinks so that a mighty mortal like me could lift them out of their holders in the transmitters.


    They were far much more impressive than the 4CX-series we had at the competing AM station.

    Our directional antenna array was located in a swamp on the edge of Lake Superior.It was always an amazing sight to see St. Elmo's fire, usually on one of the antennas during the right weather conditions. It was like we were communicating with the gods using that transmitter and antenna field.
    KJ4YEV, KA4DPO, KV4PD and 1 other person like this.
  5. W4KJG

    W4KJG Subscriber QRZ Page

    I think this is one antenna that I will leave alone. I was on 80, 40, and 20 meter FT8 with it a little earlier this evening. I never ran more than 10 watts. It was especially interesting to watch the results on PSKreporter. With 10 watts I had pretty strong signals into Europe and the Western parts of the US and Canada. I don't know why it is working so well, but I'm not going to try to improve it.
    KA4DPO, N1VAU and KJ7ZII like this.
  6. SM0AOM

    SM0AOM Ham Member QRZ Page

    In the early 1980s, there was an ambitious project operating in northernmost Norway by
    the Max Planck institute in Germany for finding out the properties of the ionosphere.

    As one part of the project, a transmitter site was built having 12 120 kW HF transmitters feeding a large phased array pointed upwards. It was possible by selecting the proper excitation frequency to create local heating and an artificial radio aurora.

    One 120 kW transmitter

    Block diagram of one transmitter+antenna

    Among the radio amateur scientists involved in the project were space physicists SM5DFW and SM5API(SK).

    WD4ELG, K0UO, KA4DPO and 1 other person like this.
  7. KV4PD

    KV4PD Ham Member QRZ Page

    HAARP come to mind. Just sayin'....
    WD4ELG, KO4PYL, K0UO and 1 other person like this.
  8. N1VAU

    N1VAU XML Subscriber QRZ Page

    You da'ham, ✊ Fist bump!!
  9. WA9SVD

    WA9SVD Ham Member QRZ Page

    I can't afford even the water bill.:(:rolleyes:
    KA4DPO likes this.
  10. KA8NCR

    KA8NCR Ham Member QRZ Page

    Has that always been an option?

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