Today Tom OE2ATN and me Wolf OE2WNL where on Sota tour with our snowshoes. We headed for 3 summits - as the weather forecast said rain/snow at noontime we started early.
When we reached the 2nd summit it started snowing (Graupel). There we recognised a cracking noise coming out of the buddypole coil and out of my skiing pole!! - awesome and scary - holding my skiing pole horizontal the cracking noise got louder - moving the pole lower the noise got more silent.
We have never experienced such an effect - but it was scary as we got electro shock when touching the coax plug - I mean I know that on the antennas there can be electric shock - but once you touched it it’s gone - but today every time we touched it made an electric shock - we immediatly unpluged it from the rig and brought the antenna down.
Then we made our 4 QSO’s with the handheld VX-7 but again within just the 30cm of antenna the cracking noise there again!!
We tried to make a video out of this which is available here:
You can find the complete blog post here:
Have you ever experienced such an effect? Interested in your comments.
In reply to OE2WNL:
I was on OE/VB-354 (Fellhorn) today and also heard this crackling noise in my antenna wire and near some metallic poles near the summit. There were sparks from the antenna wire to ground. Fortunately there is a safe shelter not far from the summit - one hour later it seemed safe to resume operation.
Das war eine ziemlich erschreckende Erfahrung … I did not expect such conditions during winter.
Greetings - Martin df3mc
Snow and associated electrical charge are well know. It is often heard on an in-car radio with an external telescoping metal whip aerial, when driving through snow, sleet (wet snow) and indeed rain/hail showers. The effect manifests itself in a frying or screeching sound - specifically on AM though I have heard it on FM.
Just before Christmas last year I was activating my local summit GM/SS-064 on 20M using a raised INSULATED wire ground plane (both radials (3) and wire radiator were mounted on my fibreglass SOTA pole - no mechanism to discharge). A blizzard swept in and covered the summit for over 30 minutes. I could hear the charge build up on the aerial as the QRN increased steadily to 9++++. I tried to get some cover behind a boundery fence. On disconnecting the BNC feed (1M of RG174 - thin coax) I got a nasty shock off the FT817.
So even using insulated wire there is enough capacitive effect to build up a healthy charge on this aerial configuration.
In future if I suspect the possiblity of stactic build up I will earth the rig with a short ‘croc-clip’ lead, which I carry, to a series of earthed tent pegs. Or alternatively drop the aerial. Though this is sometimes difficult when the mast is snowed/iced up.
Richard G3CWI also has an interesting video on you tube about this problem.
Sunday, June 12, 2011
Dangers of static
With summer approaching and the increased likelihood of thunderstorms all hilltop activators need to be aware of the risks from lightning and static. At best it might just blow the front end of your radio receiver. At worst you could receive a painful shock or even be struck by lightning (after all, an antenna on a summit may well be the highest lightning conductor in the area.)
This video by Richard G3CWI shows sparks jumping from the connector of the feeder from a 2m beam during a rain shower.
Many mountain activators have similar tales to tell - even of receiving a shock from the case of a hand held 2m radio using just a telescopic whip.
Static can be experienced even when there is no sign of thunderstorms. If the receiver starts sounding noisy, that could be static in the area. Whether you have made all your contacts or not it is probably a good time to beat a retreat for both your own safety and that of the radio.
Yes, I experienced this on The Begwns (GW/MW-025) on 11 June 2011.
I had only just set up with my FT-817 and a 28 MHz wire dipole supported by my fishing pole. I became aware of a frying/whining noise on RX, which I recognized as “thunderstorm static”. I have previously experienced this at my home station during showers of electrically charged rain.
On this occasion there was no rain falling at my location, but the whining sound was becoming ever louder. I decided to unplug the antenna to avoid damage to the front-end of the rig. Whilst unscrewing the PL-259, I received several sharp electric shocks from the metal case of the rig and from the PL-259 plug itself!
With the disconnected plug lying on the grass, bright blue sparks were jumping between the centre conductor of the PL-259 and the shell of the plug. The sparks only stopped when I dropped the fishing pole on to the ground.
Quite scary! I abandoned the activation and descended in some haste to the car. The rain started just as I reached the car, some 10 - 15 minutes later.
I was surprised that such a short wire antenna had picked up enough static to cause sparking across the plug … but G3CWI reports similar experiences with a 2m yagi!
I also experienced the same with only a 2m Yagi while activating Pendle Hill a couple of years ago. I didn’t notice the dramatic blue sparks but the noise was very obvious & caused by cloud making contact with the hill.
This video doesn’t show the noise, or sparks, but does show the conditions that produced them.
In reply to OE2WNL:
Yes, on more than one occasion.
In 2002 while activating G/NP-002. I use a four section carbon mast which screws together. The sections are held together by bungies in the rucksack but still stick up in the air. Nothing happened whilst climbing the lee side out of the wind. The moment of walking over the summit lip into the airstream caused a crackling sound from the top end of the carbon mast sections. Sparks were jumping between them. I erected the tent, HF & VHF stations and stayed a few hours intending to stay overnight but was scared from the summit very quickly when lightning and thunder became less that one second apart.
Another time, I lost the squelch circuit on my ICOM ICT-7E H/H due to static on G/LD-004. A grounding lead enabled me to carry on working stations for a while but the rig was already permanently damaged and has never squelched since. That wasn’t surprising judging by the fat blue sparks issuing from the BNC plug to ground at the rate on one per second, after the rig was disconnected. ICOM later told me that the rig was beyond economic repair.