We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissable in your locale.

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - beaconpop

Pages: [1]
1
HF Beacons / Re: Coastal Slider Back On 4109.5
« on: September 06, 2023, 1825 UTC »
Greetings to all beacon aficionados!

In the rugged coastal mountains of California, a daring mission was undertaken last week to ensure the continued operation of a certain clandestine HF beacon known as the 'Coast Slider'. Join us as we recount this thrilling adventure up a misty mountain.

The journey began under the cool embrace of morning fog, creating an eerily quiet atmosphere. As our intrepid team ascended towards the beacon site, the persistent chill in the air was a most welcome companion. The sun eventually broke through the mist, but fortunately the temps remained pleasantly cool, setting the stage for an afternoon of repair and maintenance work.

Over the winter months, it became apparent that the Coast Slider's battery was no longer up to the task, struggling to hold a charge. This left the beacon operational only during daylight hours when the solar panel received sunlight. To address this issue, a comprehensive plan was hatched: replace the aging battery AND upgrade the solar panel.

Upon summiting the ridge, we were relieved to find the CS's container and solar panel in great condition - unmolested by human hands, vexatious varmints or curious condors. With great care, the box was unsealed and its contents eaxmined. To our delight, the battery and electronics were dry and pristine, untouched by the relentless rain of an unusually wet winter. This underscored the meticulous sealing of the box's lid and cable penetrations - care taken when the CS was first emplaced nearly 18 months ago.

Our first task was to replace the battery, installing a new 3Ah SLA to rejuvenate the transmitter. NExt, we turned our attention to the solar panel, upgrading it from its original 5 watts to a more robust 11 watts. These enhancements should ensure the the Coast Slider's uninterrupted operation for an extended period.

Replacing the panel meant cutting into what had been a continuous 10' underground run of cable to the beacon's container. This task was executed with precision, and the splice was carefully sealed to prevent moisture ingress, an important step in wet coastal conditions. (Oh, for a dry desert location with mostly sunny days!)

With the upgrades complete, time was spent to assess the beacon's performance. Its output power remained steady at 1/3 watt, a reassuring sign for its continued operation. However, the SWR had increased slightly to 1.8:1 (from 1.5), most likely due to the development of 2-3' sag of the antenna wire. And the resonant frequency also shifted down from 4110 kHz to 4060 kHz. The bungee cord which served to accomodate movement of the scrawny 'pine' trees supporting the antenna was replaced with a fresh bungee cord, this time enclosed in black nylon mesh tubing to protect it from the sun. The sag was left in the wire, since the antenna had survived a number of winter storms perhaps due to the slack.

The hike and maintenance tasks had far taken longer than anticipated (they always do!), so the elevated SWR issue was left for another time.  The late afternoon sun cast long shadows as we started our descent.

Until the next adventure,
Beaconpop

2
HF Beacons / Re: Coastal Slider Back On 4109.5
« on: May 03, 2022, 0331 UTC »

Yes, hopefully the bungee cord will last a few months.

Just in case, a length of dacron para cord was paralleled with the bungee cord, so that if (when?) the bungee fails, the antenna will just sag rather than fall down.  An upgrade to a pulley and counterweight arrangement that would allow for greater movement and a constant tension is probably the way to go.

And as you noted in your logs, the beacon's frequency shift has increased to nearly 400Hz from the original design value of 170Hz. Thanks for the report. There's an RC network which determines the amount (and rate) of the shift; perhaps the component values have changed a bit. It'll be interesting to see if the delta-F stabilizes or keeps increasing.
 

3
HF Beacons / Re: Coastal Slider Back On 4109.5
« on: May 01, 2022, 1706 UTC »
About two weeks ago, a hike was made to the beacon to investigate what happened. As expected, it was an antenna problem - probably caused by high winds over the ridge in the storm also took DW out on the same day back in April.

The Slider's 70' antenna wire is supported by small two pine trees, and lacked a way to accommodate movement of those trees in the wind. The strain caused the antenna wire to part at a solder joint near the EFHW transformer, leaving only 1' of wire connected. The beacon was found to still be transmitting though. Fortunately,  the PA transistor was still OK (not surprising since the beacon only 1/3 watt).

The antenna was shortened a bit and the solder joint repaired with added strain relief. The height of the antenna was raised by an additional 10 feet. This had the happy side effect of bringing the SWR down to <1.5:1, whereas It was ~3:1 when first installed. A bungee cord placed on end to hopefully accommodate strain when the support trees move in the wind.

4
HF Beacons / Re: The 'Coast Slider' 4109.5
« on: April 01, 2022, 0027 UTC »
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


5
HF Beacons / Re: The 'Coast Slider' 4109.5
« 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

6
HF Beacons / Re: The 'Coast Slider' 4109.5
« 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

7
HF Beacons / Re: The 'Coast Slider' 4109.5
« 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

8
HF Beacons / Re: 4110 Whooper-Type Signal At 1035z
« on: February 13, 2022, 0046 UTC »
That was the Coast Slider undergoing tests at the secret beaconpop test range last month. Wow, good ears, l0ngwire!

/BPOP

9
HF Beacons / 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.

10
HF Beacons / Re: A "pop up" beacon
« on: July 05, 2021, 2254 UTC »
The repaired beacon was on the air from the bpop test range for about 1 hour that morning. Good catch!


/BPOP 

11
HF Beacons / Re: A "pop up" beacon
« on: July 01, 2021, 0355 UTC »
Sorry for the delay.. sent it as you were typing, I think!

/BPOP

12
HF Beacons / Re: A "pop up" beacon
« on: July 01, 2021, 0233 UTC »
The pop-up beacon was retrieved and debugged. Wish I had a better story, like a badger chewed the coax or the beacon was struck by ball lightning, or...? However, the reason the beacon stopped transmitting (after only 12 hours) was much more mundane: a bad solder joint in the 555 keying circuit. 

The beacon has been fixed and tested. It will be re-deployed later this summer. One enhancement will be to replace the 555 circuit with an ATTiny85 keyer to send something other than a simple periodic dash.

Many thanks the listerners who managed to catch the beacon while it worked and sent reception reports.

/BPOP

13
HF Beacons / Re: A "pop up" beacon
« on: June 26, 2021, 0352 UTC »
It appears the pop-up beacon is no longer transmitting.

It started out nicely and was being heard in CA, UT, NV and even weakly in HI (!).  But this morning only a few strong dashes were heard 5- 10 minutes apart - as if the 555 timer keying circuit malfunctioned. Nothing being heard now. There was a big rain and windstorm last night and maybe the enclosure leaked. The beacon will be retrieved and a post mortem will be performed.

/BPOP

14
HF Beacons / Re: A "pop up" beacon
« on: June 24, 2021, 1859 UTC »
Look for it at 4109.5

/BPOP

15
HF Beacons / A "pop up" beacon
« on: June 24, 2021, 1736 UTC »
Good morning!

A new low power beacon, located in a western desert, will be tested 
- starting on Thursday 6/24 at ~7:30pm pacific time (0230 UTC 6/25), and
- ending  on  Sunday   6/27 at ~1:00pm pacific time (2000 UTC 6/27).

Look for the beacon between 4100 and 4110 KHz, with a 1/2 second dash. 

Please send reception reports to beaconpop@protonmail.com. Include the location of receiver and the beacon's period to get an e-QSL with more information about the beacon.

This is only a short 2.5 day test of the beacon TX, the site, and solar and antenna  performance. If all goes well the beacon will be permanently emplaced and run 24/7 later this summer.

Many Thanks,
BPOP
 

Pages: [1]
HFUnderground T-Shirt
HFUnderground Garden Flag
by MitchellTimeDesigns