Topics and links of the broadcast 19-03-2023 11:00 am (CEST)
PROBLEM Service Alert: 5 GHz Backbone PI3ZLB -> PE2KMV/5 GHz QRG is CRITICAL (by PA0FOT)
The radio connection with the remote receivers of the repeater PI3ZLB has been disrupted since tonight, the cause is unknown. The repeater itself seems to function normally, but the remote receivers are not usable when the connection is down. The accessibility will be a bit less for some participants over this repeater.
Notification Type: PROBLEM
Service: 5 GHz QRG
Host: 5 GHz Backbone PI3ZLB -> PE2KMV
Date/Time: Sat Mar 18 21:54:34 CET 2023
Wow! Sun Just Produced a Carrington Like Event, But We Got Super Lucky
Anton Petrov made a video about the recent Carrington event where a G1 possibly a G2 event took place. In this video he talks about similar events in the past and explains what that means for us and how lucky we were. This event has caused hickups in sensitive computer connections in some places.
More information in the video can be found here.
Class-E Power Amplifiers for Radar for Deep-Space Missions
Class-E amplifiers provide high efficiency, low parts-count solutions for RF and microwave power amplifier applications. These amplifiers utilize an output network which allows voltage across or current through the single switching transistor, but not both simultaneously. By avoiding the overlap of voltage and current in the transistor, device dissipation is reduced.
Lower dissipation means higher efficiency, lower heat load, and substantially more output power from a given device. Because the output network can absorb the capacitance of the active device, it is possible to extend the upper frequency limit of a particular transistor. Class-E amplifiers have been built and tested for use at HF, VHF, and UHF. A 50 MHz amplifier for the Europa Orbiter Radar Sounder produces 30 watts with 90% drain efficiency.
A schematic for the Radar Sounder Class-E amplifier with driver stages is shown, along with a system block diagram including a simple transmit-receive switch, and possible telemetry. Where the non-linear nature of a switched-mode amplifier is acceptable, the Class-E amplifier’s savings in power, weight, and heat make it attractive for spacecraft use.
From RSGB news (by PC5D)
The next Tonight@8 live webinar is scheduled for Monday, April 3 with a presentation called "Sheep Worrier: A High Altitude Balloon Flight and Recovery System" by Heather Nickalls M0HMO. Heather will give an introduction to altitude balloon flying, the radio systems involved, some of the science experiments she performed during her flights, the recovery system developed to recover the payload when it lands and, of course, many photos from ' almost' the edge of space.
You can ask live questions during the presentation via the RSGB YouTube channel or the special channel of the British Amateur Television Club (BATC). More information about this and other webinars can be found on the RSGB website at rsgb.org/webinars
Radio propagation and news (by PC5D)
Propagation news is curated by Tom PC5D. In the composition he makes other use of the information relevant to the Netherlands from the weekly Propagation News of the British radio amateur association RSGB, dxinfocentre , darc.de/der-club/referate/hf/ , Make More Miles on VHF and poollicht.be. Propagation news is also part of the radio news of the South Limburg Sunday morning round. The audio recording of this round is back listened on a22.veron.nl
The past week was split in half in terms of HF propagation. The first half of the week was characterized by excellent conditions on the higher HF bands. The Kp index was low, there was a lack of solar flares and the solar flux index was high perfect for HF. There were reports of 10m gaps to Hawaii and Alaska and even into the Pacific at night.
Last Monday, satellites observed a violent coronal mass ejection from the far side of the sun. The special thing about this was that the matter ejected into space reached a speed of 3000 km/s, which corresponds to about one percent of the speed of light. Such events only occur once every ten years. On Wednesday, however, there were two Kp indexes close to 6, as the Earth was hit by a fast solar wind with a Bz pointing to the south. Its impact on the ionosphere was rapid and very damaging, such that iono probes could not detect the F2 layer.
The result was a radiation storm in which the heavy protons in the polar regions of our earth ionized the D region to such an extent that the lower shortwave region could no longer pass through. And also on the higher bands, the propagation over the polar caps was noticeably worse than normal. This so-called polar cap absorption lasted three days, then it was over. The MUF really collapsed Wednesday afternoon, the 10-m band was much shorter and only open in southern directions. Meanwhile, solar activity fell to 134 flux units, as did flare activity, and there were no more M flares for several days. It was not until Friday at 1500 UT that another very weak M flare was recorded. Solar activity showed itself more in filament eruptions, i.e. plasma arcs that can leave the sun as CMEs. So the sun takes a bit of a break, the sunspot groups are reduced to three, and a very small single spot can also be observed.
Expectations for solar flux are around 130, and the 150 mark will not be crossed again until next weekend. Indeed, there are indications that two larger active regions on the eastern edge of the sun will turn in, so that all bands will open reliably again next week, as has been the case in recent weeks.The Kp index will remain low for the time being, but may temporarily increase to 4 in the night from Sunday to Monday when wind speed and geomagnetic activity pick up again.
In the coming days, an offshoot of a low pressure area near Scotland will determine the weather in our region. Moist air is being brought in from the southwest so that stations in the south may benefit from somewhat improved tropo conditions towards France and Spain. During showers there is a chance of rain scatter on the GHz bands. For Aurora, the K index is still too low and we are waiting for more activity on the sun.
For Spoaradic E at 6m and above it is still too early. In April it will again be more relevant to keep an eye on the jet streams. Sporadic-E activity is often geographically related to the position of jet streams. For EME operators, the Moon's declination is low, but rising. She will turn positive again on Wednesday, which means the availability time of the moon is getting longer.
The moon is standing today at perigee, so path losses are minimal. 144MHz sky clutter is low this week, except for all of Tuesday when the sun and moon are nearly eclipsed.