Is the Desert Whooper OK?

[stendec]

For the past two weeks, DW signals have been considerably weaker than usual. Just me, or has anyone else noticed it?

In the past, DW was often a couple of S-units stronger than the Coast Slider, but now the situation is reversed. DW was typically S4-5 on the KFS and KPH SDRs, except for afternoon fades. But lately it is only S1-2, if I hear it at all.

[Dave Richards]

Yes, I have noticed it too.

[Desert Whooper]

Thanks for noticing the drop in signal strength!

We visited DW in late February and even though it was operating well we noticed deliberate damage to the stake that guided the coax up to the antenna. The stake was snapped off at ground level. This caused us to recognize that a number of other things that had happened over the years were neither random or caused by animals or even absentmindedness. It's now recognized that someone has repeatedly attacked our temperature beacon. Motivation is unknown.

Roughly in order:

The shielded cable that connects the temperature sensor was torn off and pulled away as far as it could go. We thought some crazed animal was The Culprit.

The plastic shield covering the temperature sensor was smashed into a million pieces that were scattered all over the ground. Maybe some local raptor ran into it in high speed pursuit of a rabbit?

Although the pelican case has padlocks the latches were loose and the cover was open about a quarter of an inch. The case is anchored in place by a buried cable. I thought we had somehow locked it up without snapping the latches first?

The lightweight steel post that held up the temperature sensor assembly was bent over flat against the ground. The winds there can be fierce but the post and sensor have little surface area for that kind of wind loading. Deliberate attack?

As mentioned, the antenna cable guy stake was broken off at ground level. Maybe some enraged beacon hater kicked it?

As you observed, DW's strength dropped off precipitously. Our worry now is that the longwire antenna has been vandalized. Hopefully it was simply a failure of the wire breaking apart so a Dacron guy line will be added to support the center  balun feed and allow lower tension on the active elements.

We will schedule a trip to the site with materials to rebuild the antenna, or coax or possibly replace the transmitter's output transistor in case the antenna is okay.

We'll report again after repairs are effected.

[syfr]

That sucks, as it's a wonderful beacon that has provided a lot of fun for a lot of people.

Perhaps a relocation might be useful to evade the two legged vermin?

[mark-n-nut]

pssst!   hearing DW at 0230 this evening not very strong here only S-4 to 5.  Nice work!

73, Mark

[Desert Whooper]

Thanks for the signal reports! Here is what we found:

The broken coax anchor allowed the antenna to sway with the wind. Due to a flaw of our balun mounting arrangement the balun could be rotated a few degrees as the antenna swayed. This caused one of the two antenna connecting wires to break.

DW may have kept running for a while but eventually the transmitter's output Mosfet failed. Possibly high VSWR damaged it

We replaced the Mosfet, added a coax cable anchor and reconnected the antenna wire to the balun. If we visit again we will bring out a balun with better mounting/suspension points. 

Relocating DW would be a hard decision to make. It is along a path where the bighorn sheep migrate and why we are collecting temperature data

[Dave Richards]

DW currently coming through on the KFS SDR at a 539, at 1515z. The bands have been in the doldrums recently, so this is an encouraging result. It's good to have this robust signal back. The telemetry makes it more appealing than the average beacon; to me, at least. The connection with data collection in connection with the migration of bighorn sheep is interesting too.