Propagation through this session in North America was bizarre and continued into daylight this morning. Before I continue I should report that WSPRnet seemed to be experiencing a significant amount of downtime through this session so it makes accurate analysis quite difficult. Its possible that the band was more open than has been reported but with missing data due to upload and server problems, we may never know.
Early in the evening I noted in the ON4KST chat/logger that the band didn’t “feel” right. Local noise was extremely low, literally S0 – S1, but incoming signals appeared to be subject to deep fades on the longer paths while the short hops were stronger than normal. WD2XSH/15 in Little Rock, Arkansas was reported here at -6 db S/N during the observation period and these CW-level reports continued through the evening while many other signals that are normally strong struggled to maintain JT9 or even detection limit levels. I should also note that this short hop behavior was seen this morning in the reports from Jim, W5EST, also in Little Rock, who continued to report my signal well after local sunrise here in Texas.
From another perspective, Doug, K4LY / WH2XZO, in South Carolina, reported very quiet conditions and record or near record reports of -5 db S/N from WH2XXP in Arizona (89 total reports), with no reports from Larry, W7IUV / WH2XGP, in Washington state (Larry notes that he used reduced power due to overnight weather conditions). Larry reported generally mediocre conditions with no east coast stations. Doug also noted that signals along the east coast struggled, as did reports on the trans-Atlantic and transcontinental path to Hawaii from South Carolina. What makes all of this so curious, which Doug points out, is that there have been no solar flares and solar wind has remained in the low category.
From yet another perspective, John, WA3ETD / WG2XKA, indicates that activity seemed to be down but the high latitude transcontinental path to the Pacific Northwest appeared to be open to some degree with reports from Steve, VE7SL.
Neil, W0YSE/7 / WG2XSV, notes 14 unique reporting stations with KL7L representing his best DX. He had no reports for Merv, K9FD/KH6 / WH2XCR. Neil also notes that he decoded WE2XPQ seven times during the session, with best report at -26 db S/N.
So the band was all over the place and with the WSPRnet difficulties its probably not likely that we can really make a valid assessment.
The geomagnetic field was very quiet during the evening in North America, increasing slightly on the approach to sunrise but still remaining quiet. Solar wind continues to be very low, in the 200 – 300 km/s range. The Bz has remained southerly through the session. Its possible the lack of a “spark” due to low solar activity coupled with the south-pointing magnetic field is shutting down or degrading propagation. That’s about all we can grab on to at the moment.
WSPR activity levels are difficult to assess due to WSPRnet outages through the session. At one point during the evening in North America, 74 MF WSPR stations were observed but I do not trust that count. New or newer (or returning) stations include N8WAC and W7CSD. Welcome aboard and thanks for your reports. There were two stations in North American that contributed to map pollution, making operator distribution analysis difficult. One station was located in W4 and the other in W5. Please use care when switching bands! If you need help, contact me and I can explain how to properly change bands so that stations from other bands don’t show on the MF map. Thanks!
Regional and continental WSPR breakdowns follow:
There were no trans-Atlantic or trans-African reports during this session.
In the Caribbean, Eden, ZF1EJ, provided reports to southern stations as well as both stations in Vermont, where the path is mostly salt water.
In Alaska, Laurence, KL7L / WE2XPQ, did not see a repeat of the path to JA1NQI-1 but had a number of solid reports at JT9 levels with Hawaii and the Pacific Northwest / western Canada. KL7L was designed as receive-only.
In the Pacific, Merv K9FD/KH6 / WH2XCR, was reported by KL7L, JA1NQI-2 and VK2XGJ on the Pacific paths with good coverage of western North America. As noted earlier, the path to the eastern mainland US was degraded through this session.
Additional anecdotes, statistics, information, and comments:
Jim, W5EST, provided the following commentary:
“VIEWPOINT: SAFETY COLLAR ON FIRST SEVERAL FEET OF 630M VERTICAL
A reader wanted details about an antenna safety collar concept mentioned in the Jan. 15 blog post. While Part 5 ops know how to operate a TX vertical safely, hams new to MF should be informed about the safety dimension of MF/LF if and when such bands do finally come to hams from the FCC.
At a given TX power output TPO, radiated RF on 630m is much less than on HF–but the antenna voltage is far higher than on HF. A 630m TX can run full power for minutes at a stretch with QRSS and some digital modes like WSPR and JT9. People and animals may intrude if fencing is ignored or insufficient. Can an antenna safety collar help?
Just tape-wrapping or lacquering the first several feet of vertical probably wouldn’t make it safe enough to touch, due to capacitive RF current through thin insulation. Since the KVs of voltage are at radio frequency, a capacitive current calculation helps supplement the usual insulation assessment you’d do for a high-voltage conductor at DC or 60 Hertz.
Accordingly, a PVC tube with top and bottom seals would safety-collar the vertical for the first several feet of its reachable height. The seals on the PVC tube would hold its inside diameter firmly, to leave a concentric air gap around the vertical antenna conductor diameter. The seals would bear wind loading the PVC outside diameter.
OK, so what estimate do you get for the capacitive RF current that would flow if somebody barefoot accidentally put their hand on the PVC with full TX power on?
First of all, PVC with air gap to metal would interpose a higher, safer capacitive reactance than PVC itself on metal. (PVC has ~2.3 dielectric constant.) The capacitive peak RF current is the RF peak voltage divided by the capacitive reactance 1/(2π f C) of the capacitor C formed by part of a person’s hand touching the PVC tube.
That all works out to: RF current ~= 4 milliamperes x KV x C(pF) at 630 meters.
I don’t know the RF voltage and the PVC and vertical outside diameters you might use. But I can make up an example.
Capacitance roughly equals εA/d, where ε is about 9pF/meter with PVC-airgap construction. Capacitor area A of a hand-touch may be roughly 0.001m^2. Picture a 0.01 meter PVC air gap to the vertical inside, carrying 13 KV at 5 watts EIRP on 630m. Then:
RF current = 4mA x 13 KV x 9pF/m x 0.001 m^2 / 0.01 m =~ 50 mA.
This all presumes that nobody barefoot might touch the antenna PVC in any weather but dry air while TX was running. Even in dry air, that 50 mA figure provides a back-of-the-envelope value that warns us that we could conceivably get an RF burn or memorable “Ouch!” experience even using a PVC collar on the vertical. But that’s good news compared to some worse alternative, right? 73!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page!