HFU HF Underground
Loggings => HF Beacons => Topic started by: beaconpop on February 12, 2022, 0617 UTC
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The old Pop-Up Beacon, much modified and renamed to the "Coast Slider" was emplaced
in the coastal mountains of central CA and switched on yesterday at 2330 UTC,
(3:30pm CA time).
The beacon has undergone substantial modifications from its earlier incarnation
as the PUB: *lower* power, smaller enclosure and solar panel, and a unique antenna.
A 'slide' (whoop) was purposely added to provide the beacon with a distinctive
audio and waterfall signature.
Still recovering from the hike, unseasonable heat and hours of install work, but
will provide more beacon details soon.
Reception reports are appreciated.
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I heard it fairly strong here in Santa Barbara, about S4 at 0930z. I was in the CW mode, and logged it at 4109.7.
Thanks for putting it up! Are you also the sponsor of the F beacon that is sometimes heard around 4100? I've not heard that one for a week.
1015z Update: I can no longer hear it... Also nothing heard on the KFS SE SDR or the Token/Mojave SDR.
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Best heard on the KFS omni rather than any of the directional antennas
(https://i.ibb.co/Jp6qGK0/Coast-Slider-1.png)
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The old Pop-Up Beacon, much modified and renamed to the "Coast Slider" was emplaced
in the coastal mountains of central CA and switched on yesterday at 2330 UTC,
(3:30pm CA time).
The beacon has undergone substantial modifications from its earlier incarnation
as the PUB: *lower* power, smaller enclosure and solar panel, and a unique antenna.
A 'slide' (whoop) was purposely added to provide the beacon with a distinctive
audio and waterfall signature.
Still recovering from the hike, unseasonable heat and hours of install work, but
will provide more beacon details soon.
Reception reports are appreciated.
Annnnd...... CONGRATULATIONS!!
I was just up that way visiting some old VLF NDBs that were shut down after GPS made them obsolete. That was pretty hot weather to be out for a full beacon install! I'm looking forward to the tech details.
Moro Bay 310 KHz NDB "MB" (off the air), sadly vandalized. The AC power meter was not spinning.
(https://i.ibb.co/jZ6mcFY/IMG-7608-600x800.jpg)
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The Coast Slider runs 335 mw (Po, measured into a 50 ohm load) to an end-fed half-wave antenna. The EFHW is 15' off the ground and strung between two pine trees. Those trees, however, are located a 2000' ridge! An EFHW for 4.1 MHz would normally be 115' long (like the original Pop-up beacon). The CS antenna is shortened to 70' using a center loading coil.
Prior to the install, the antenna was to pruned to resonance. However once on site, it resonated 170kHz lower, with >3:1 SWR. Some power is being lost due to the mismatch. Further antenna trimming on site was not performed. It was pretty hot and I should have carried more water.
The CS has has enough battery power for ~72 hrs, so if it is still transmitting 24 hrs from now, that's a good sign and means the solar charger is working.
Thanks for the reception reports and keep 'em coming!
/BPOP
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I heard it fairly strong here in Santa Barbara, about S4 at 0930z. I was in the CW mode, and logged it at 4109.7.
Thanks for putting it up! Are you also the sponsor of the F beacon that is sometimes heard around 4100? I've not heard that one for a week.
No, the F beacon is not mine. One is enough!
/BPOP
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I can hear CS here at home on my KX3, weak but readable with some fading
Decent signal on the Utah Omni http://kiwisdr1.sdrutah.org:8073/
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The Coast Slider runs 335 mw (Po, measured into a 50 ohm load) to an end-fed half-wave antenna. The EFHW is 15' off the ground and strung between two pine trees. Those trees, however, are located a 2000' ridge! An EFHW for 4.1 MHz would normally be 115' long (like the original Pop-up beacon). The CS antenna is shortened to 70' using a center loading coil.
Prior to the install, the antenna was pruned to resonance. However once on site, it resonated 170kHz lower, with >3:1 SWR. Some power is being lost due to the mismatch. Further antenna trimming on site was not performed. It was pretty hot and I should have carried more water.
The CS has has enough battery power for ~72 hrs, so if it is still transmitting 24 hrs from now, that's a good sign and means the solar charger is working.
Thanks for the reception reports and keep 'em coming!
/BPOP
Tech questions & comments:
Is that coil in the 35 to 40uH range?
Any idea of what sort of radiation pattern the antenna should provide?
The change in resonance might be due to a change in soil conductivity and/or antenna height above ground. The VSWR curve probably looks like a narrow notch and it shouldn't take too much adjusting to get down close to a better match.
You could run a full 115' and start with the feed point at ground level and raise the far end up until the match looks good.
Is the antenna oriented N/S or E/W?
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Weak but getting into Hawaii
mauisdr.wsprdaemon.org:8074
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Nothing here in NW Indiana right now. I lived in the Fresno area for 6 years so I feel for the beacon's owner comments about water / hiking...even this time a year there it gets HOT. I'd love to see a schematic of the beacon, with particular interest in the solar portion.
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>Tech questions & comments:
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>Is that coil in the 35 to 40uH range?
21uH
To visualize the antenna: the feedline runs from the TX to a 9:1 impedance transformer. One side of the xfrmr connects to the 70' main radiator wire the other side to a 5.5' counterpoise. The loading coils is in the center of the 70' wire. It was designed using NEC4 antenna modeling. Modelling indicated that feedpoint impedance of a 70' loaded EFHW ~450 ohms (much lower that the full size 115' EFHW) so a 9:1 transformer was used as opposed to 49:1 or 64:1.
>Any idea of what sort of radiation pattern the antenna should provide?
Same as any low dipole: cloud burner/NVIS mostly.
>The change in resonance might be due to a change in soil conductivity and/or antenna height above ground. The VSWR curve >probably looks like a narrow notch and it shouldn't take too much adjusting to get down close to a better match.
I suspect you are correct. Antenna modelling gave lengths of 72' (and 8' counterpoise). Then it was pruned to resonance to the final lengths above at 12' height over damp clay soil. Yes, narrow SWR curve. The final install was 15' height in dry sandy soil.
>Is the antenna oriented N/S or E/W?
N/S
/BPOP
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The sweeps provide distinctive audio for the SWL’er as well as an easy to spot visual pattern on the waterfall display of Kiwi SDRs.
A 'slide' (whoop) was purposely added to provide the beacon with a distinctive audio and waterfall signature.
The dangerous whooping beacon fever is spreading! Just kidding!
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>Tech questions & comments:
>
>Is that coil in the 35 to 40uH range?
21uH
To visualize the antenna: the feedline runs from the TX to a 9:1 impedance transformer. One side of the xfrmr connects to the 70' main radiator wire the other side to a 5.5' counterpoise. The loading coils is in the center of the 70' wire. It was designed using NEC4 antenna modeling. Modelling indicated that feedpoint impedance of a 70' loaded EFHW ~450 ohms (much lower that the full size 115' EFHW) so a 9:1 transformer was used as opposed to 49:1 or 64:1.
>Any idea of what sort of radiation pattern the antenna should provide?
Same as any low dipole: cloud burner/NVIS mostly.
>The change in resonance might be due to a change in soil conductivity and/or antenna height above ground. The VSWR curve >probably looks like a narrow notch and it shouldn't take too much adjusting to get down close to a better match.
I suspect you are correct. Antenna modelling gave lengths of 72' (and 8' counterpoise). Then it was pruned to resonance to the final lengths above at 12' height over damp clay soil. Yes, narrow SWR curve. The final install was 15' height in dry sandy soil.
>Is the antenna oriented N/S or E/W?
N/S
/BPOP
I'd guess that the change in soil conductivity means the antenna might be lowered even more to bring the VSWR down. Another option is to just run the counterpoise full length. EFHW antennas tend to "use" the coax braid as a counterpoise so adding some ferrite chokes near the feed could get rid of that. Another trick is to add some capacitance to the 9:1 to resonate out any stray inductance and make the transformer more efficient. I use EFHW when I am portable but for efficiency I prefer a CFHW and a 1:1 balun to maximize efficiency. With that coil in the middle of your antenna you end up needing to prune both wire halves to keep it balanced. That's about as much work as trimming a CFHW.
With all of the cheap autotuners from China one could almost include one in a beacon and let it deal with the seasonal changes that impact antenna performance. Example is rainy weather soaking the ground and improving conductivity. There's an article out there called "The earth detunes my antenna" that offers great insights.
I do realize that now that the beacon is deployed it is difficult to go back out many times to tweak things, but maybe if you ever build another beacon some of these things might apply. I hope that CS enjoys a long life!
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Hearing it weak but readable right now, here at home
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Nice signal in the extreme south!! 459 with QSB at 0354.
Congrats on a good job!!
This is the first night I've heard your beacon, skip gets a little long here at this time.
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Pretty decent signal into Utah right now http://kiwisdr1.sdrutah.org:8073/
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Very weak but still recognizable signal here at home on the KX3
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last Friday I was out in the southern back country of Death Valley. I put up a long wire and attached the KX3 and heard CS quite well.
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I've tuned in at random times after dark looking for this, but no luck from my QTH. I did copy it on the KPH kiwi SDR c. 0450 UTC this evening, not super strong but perfectly readable.
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I can hear CS on the Utah kiwi #1 but not on KFS at all. I do hear DW everywhere on all kiwis I pick. Interesting propagation
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Looks as if CS has passed the 2 week mark without a hiccup, a good sign for it to be operating for many years to come.
I'm hearing it on the KFS Omni at the moment but not at home.
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Still going strong. Not hearing it at home right now but it's strong on the KFS Omni
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strong on the KFS Omni
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Good copy on the Coast Slider last night - up to S5 or so on my home RX (in northern CA). I note that CS is typically 1-2 S units weaker that DW at my location.
I hear CS with S3-S4 signals most mornings and evenings. At mid-day it often fades out, perhaps due to D-layer absorption. CS disappears at night but then can be heard weakly on the the N. Utah, Maui and some other western SDRs that have good antennas
(i.e. not magnetic loops).
STENDEC
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Strong signal here to tonight for some reason. Usually I don't get a copy on the Slider, but tonight at 0420Z it's 589?
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Hearing it here at home, just barely whooping above the noise.
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Thanks for the reception reports and keep 'em coming!
/BPOP
Hey there! Is the beacon off the air?
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Yes, evidently the beacon is no longer operational.
It's a mystery as to what happened to it, and it'll be a mid June before I can take the hike to even check on it. Hopefully it can be repaired on-site, otherwise it'll have to be brought in for repairs. CS will be MIA for a few months.
:(
/BPOP
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Yes, evidently the beacon is no longer operational.
It's a mystery as to what happened to it, and it'll be a mid June before I can take the hike to even check on it. Hopefully it can be repaired on-site, otherwise it'll have to be brought in for repairs. CS will be MIA for a few months.
:(
/BPOP
Thanks for letting us know!