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Author Topic: The 'Coast Slider' 4109.5  (Read 4585 times)

Offline beaconpop

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The 'Coast Slider' 4109.5
« on: February 12, 2022, 0617 UTC »
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.
/BPOP

Offline l0ngwire

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Re: The 'Coast Slider' 4109.5
« Reply #1 on: February 12, 2022, 0950 UTC »
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.
« Last Edit: February 12, 2022, 1022 UTC by l0ngwire »

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #2 on: February 12, 2022, 1536 UTC »
Best heard on the KFS omni rather than any of the directional antennas

Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #3 on: February 12, 2022, 1609 UTC »
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.




Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline beaconpop

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Re: The 'Coast Slider' 4109.5
« Reply #4 on: February 13, 2022, 0154 UTC »
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
/BPOP

Offline beaconpop

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Re: The 'Coast Slider' 4109.5
« Reply #5 on: February 13, 2022, 0200 UTC »
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
/BPOP

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #6 on: February 13, 2022, 0234 UTC »
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/
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #7 on: February 13, 2022, 0250 UTC »
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?
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #8 on: February 13, 2022, 0621 UTC »
Weak but getting into Hawaii
mauisdr.wsprdaemon.org:8074
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline N9QIW

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Re: The 'Coast Slider' 4109.5
« Reply #9 on: February 14, 2022, 0302 UTC »
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.

Alex
N9QIW
Winfield, IN

Offline beaconpop

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Re: The 'Coast Slider' 4109.5
« Reply #10 on: February 14, 2022, 0534 UTC »
>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
« Last Edit: February 14, 2022, 0544 UTC by beaconpop »
/BPOP

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #11 on: February 14, 2022, 1628 UTC »
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!
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #12 on: February 14, 2022, 1651 UTC »
>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!
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline Teotwaki

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Re: The 'Coast Slider' 4109.5
« Reply #13 on: February 15, 2022, 0301 UTC »
Hearing it weak but readable right now, here at home
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline zeak

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Re: The 'Coast Slider' 4109.5
« Reply #14 on: February 15, 2022, 0356 UTC »
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.
Zeak,

Receiver KiwiSDR
Ant(s): 80m dipole at 15m and 1m Loop
Location:  DM12

 

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