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Messages - Desert Whooper

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HF Beacons / Re: Long Dasher On 4069.4
« on: April 15, 2022, 0146 UTC »
DW sustained some damage from possibly a close but not direct lightning strike. The micro controller, battery charge controller and solar current sensor were all damaged.
A "zap trapper" is now installed in the coax path.

DW is now back on the air.  ;D

We are hoping to see the Coast Slider back ASAP!

HF Beacons / Re: The Desert Whooper
« on: April 15, 2022, 0141 UTC »
DW is operational again!

We found that when first activating DW this morning the BAT and PV numbers seemed incorrect. It turned out that the solar charge controller was also damaged. It was a quick module swap out and all is good again. Signal strength seems good so we'll be watching DWs telemetry and keep our fingers crossed.

HF Beacons / Re: 4095.6 - the Desert Whooper Returns
« on: April 12, 2022, 0028 UTC »
thanks for the report Stendec!

It was probably failure induced by a nearby lightning strike. Dead uP and current sensor

Everything is packaged watertight. No target practice occurred. Antenna looks good.
No chewing has occurred yet. External cables are protected decently.

DW Team

HF Beacons / Re: The Desert Whooper
« on: April 12, 2022, 0022 UTC »
DW was retrieved and is undergoing testing and repairs. There seems to have been some lightning strikes nearby, possibly from that big storm.. The processor was dead and possibly the PV current sensor is dead too.  Nothing is burned so maybe a quick overvoltage event? The antenna seems fine but a low voltage gas tube arrester was installed on the coax even though it's not certain that was the surge entry point.

We hope to have DW back in the desert soon. We're losing temperature data!

DW team

HF Beacons / Re: The Desert Whooper
« on: February 22, 2022, 0125 UTC »
Today is DW's first birthday! We installed a new solar shield for the outside temp sensor and retensioned the antenna guy lines.

Thanks to all for the signal reports and qsl requests!

The DW Team

HF Beacons / Re: The Desert Whooper
« on: February 22, 2022, 0120 UTC »
Hey Desert Whooper

Can I drop in at the "Ranch" for DW's 1 year of operation party?

Just Kidding! Spotted this off ramp sign on one of my road trips.

Good one! Might use it on
 QSL cards


HF Beacons / Re: The Desert Whooper
« on: October 27, 2021, 1852 UTC »

Wow! That's pretty good for a watt.  I would LOVE to see the perfect antenna/matching/ground system he's got on it :D

A lot of time was spent trying to determine how much transmit power was appropriate. After extensive research about QRP rigs one watt seemed appropriate.  Next antenna efficiency and pattern were focused upon.

The desert soil is very rocky and dry so the antenna is hung relatively low to achieve a 50 ohm match close to 1:1 vswr. From the ideal free space length the antenna was shortened 92" to achieve the match. There are no additional ground rods or counterpoise elements strung out beneath the antenna.

Balun efficiency was also  looked into and a simple 1:1 "transformer" of coax wound on a large core had the lowest loss.

HF Beacons / Re: New whooper beacon on 4095.65
« on: September 19, 2021, 2135 UTC »
All of the reception reports are very much appreciated and are a bit exciting too! This is the first HF telemetry beacon built by the DW team and the temperature reporting has filled a gap in our remote location weather data used for evaluating bighorn sheep migration patterns. Some of the government weather stations in the general area have been proven to be unreliable so we decided to build a weather station of our own.

Development started around September of 2010 utilizing a shortened antenna for local reception in our  city.  It was quite a surprise to read that the KFS SDR's still heard the beacon! That was unknown by us until reading of it here. As reported here on HFU, the whoop pattern and telemetry evolved over the months but were finalized early this year so as to commence with the beacon's final construction and testing. The beacon's on site installation turned out to be quite a challenge too, including backpacking the hardware to the site and reducing the visual signature of the equipment.

The transmitter's "whoop" was engineered to provide a distinctive yet consistent pattern that could worm through noise and interference yet fit within CW bandwidth filters. It also provides a sense of time between telemetry reports.

A reliability issue with the final amplifier was resolved with a redesign and retrofit. The 2N3866 bipolar transistor was replaced with a more robust IRF510 MOSFET that is not fazed by the 120 degree internal temperature peaks. The transmitter circuit has a jumper set up to allow bypassing the MOSFET for a final  output of only 200 mW. The MOSFET is slightly less efficient but the battery and solar panel are sized to provide at least three days of run time in heavily overcast weather so there is little impact from reduced efficiency..  The BAT and PV telemetry show the battery should provide a long life before requiring replacement. Hopefully the beacon continues to run well in the winter months.

The antenna system was a challenge to engineer but has exceeded all expectations as proven by the reports that all of you have generously supplied. Despite primarily aiming for NVIS operation over the area of interest the broader coverage across North America is turning out to be very beneficial due to the broad public network of HF SDRs.

The DW Team

HF Beacons / Re: HF Beacon Frequencies
« on: September 12, 2021, 2209 UTC »

(also responsible for Windy and maybe DW... ;-)  ...).

Terribly wrong old chap. DW is collecting temperature data for our Desert Weather group. We have no idea who owns Windy

HF Beacons / Re: The Desert Whooper
« on: August 25, 2021, 2156 UTC »
Thank you very much for the detailed report along with the picture and audio recording! You must have a low noise floor there. Great audio quality and quite a thrill to hear the Desert Whooper through your SDR

The eQSL will be in your PM inbox in a minute


HF Beacons / Re: New whooper beacon on 4095.65
« on: August 22, 2021, 2155 UTC »
Thanks for the logs

HF Beacons / Re: The Desert Whooper
« on: August 22, 2021, 2154 UTC »

The Desert Whooper Beacon 4095.65 KHz
In your August 4th logs a person offered some incorrect information about DW’s transmit format. For your readers’ interest, here are some technical details of the one watt beacon that provides fascinating propagation performance.

The beacon started development in November of 2020. It was built from scratch and has a hybrid controller consisting of two 555 CMOS timers to key the transmitter along with an Arduino Nano controller to generate Morse code and collect data for performance telemetry. The 555 timers will independently key the transmitter if the Nano fails for any reason. (Fortunately the Nano has functioned for 10 months without issue.) The 4.09565 MHz transmitter is crystal controlled and features a MV1403 varactor diode circuit for the upward frequency sweeps of 150 Hertz. 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. The transmitter has 4 transistors and the final amplifier is a IRF510 MosFet followed by a low pass filter, all inside a shielded box.

The beacon is powered by a sealed lead acid battery which is kept charged with a solar panel. The battery is protected from over discharge by a low voltage disconnect (LVD) circuit that is independent of the Nano. Time has shown that the solar panel size provides good charge current even in cloudy weather and the beacon does not draw much battery power overnight.

The antenna is a 111 foot long, 1/2 wave dipole oriented North/South and it’s about 0.1 wavelength above the dry desert soil to create a more vertical but omni-like pattern. The 1:1 balun is home made and the antenna’s measured VSWR is close to 1.1 to 1

There are six cycles of DW in Morse along with 29-30 “whoops”; then the DW identification is sent along with four different telemetry numbers.

Telemetry is in slow Morse code as follows:

BAT is the battery’s voltage to tenths of a volt using a precision resistor divider and the Nano’s A2D function. Normal values range from 12.8 to 14.4 volts
OTMP is in degrees F with a calibrated 10k NTC thermistor located outdoors, about 100′ from the beacon.
ITMP is in degrees F provided by a digital one-wire DS18B20 microLAN sensor located within the weathertight equipment box. The reading runs 5 to 10 deg warmer than OTMP.
PV is given in milliAmps to monitor solar panel performance and battery charge current. Measurements are based on an INA219 current sensor board. The values of the current can range from 0 to 2000. Note that a value of 4 or 5 is just the idle current consumed by the solar controller because the battery is fully charged.

In case the Nano fails, the number of whoops can decrease from 30 down to 29 as a crude measure of rising temperatures. On some recent days the internal temperature has peaked at 120 degrees F when outside air temperature was measured at 112 degrees! The box is in shade but the electronic circuitry generates waste heat that causes the temperature rise. Monitoring the temperatures during night and day provides for some interesting deltas..

DW was officially deployed to the Western desert on February 21, 2021. It has been heard in Canada, California, Hawaii, Maryland, Utah, Arizona and many other locations. Some SWL logs can be seen here: https://www.hfunderground.com/board/index.php?board=9.0 and eQSLs are being provided.

The DW Team

HF Beacons / Re: The Desert Whooper
« on: August 22, 2021, 2146 UTC »
Please post up here if you requested an eQSL but did not receive it.

HF Beacons / Re: The Desert Whooper
« on: August 16, 2021, 2328 UTC »
For the eQSL please send a detailed reception report to Desert_Whooper at protonmail.com

Please include the time, date, DW's telemetry readout, signal strength/quality, your approximate receive location, radio receiver and antenna used.

Am still searching for a deal for printed QSL postcards.

HF Beacons / Re: HF Beacon Frequencies
« on: August 16, 2021, 2322 UTC »
The 4.09565 KHz  frequency for DW was selected to achieve good propagation with low power in a frequency band that is little used for maritime comms.  Crystals are cheap and 4mhz is a popular frequency range for a number of beacons.

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