Maybe it was the fact that many of us have not seen a good session in almost a week, but last night was a nice improvement. Band noise was extremely low here in Texas and signals were strong. The lightning map indicated very few pockets of lightning on or near the North American mainland. Geomagnetic conditions were also improved but solar wind continues at moderate levels.
Neil, W0YSE/7 / WG2XSV, reported a good night after spending a few nights on 160-meters. He also notes first time reports from WH2XES who is local “microwave guy” Al Ward, W5LUA. Neil’s complete report follows:
Ken, K5DNL / WG2XXM, reported that he decoded by ten unique stations and was decoded by 47, including WE2XPQ. He had 49 reports from WH2XCR and 93 spots from VA7JX. KU4XR was hearing well, providing Ken +16 dB S/N reports.
Doug, K4LY / WH2XZO, continues to have some QRN but judging from the reports, he had an effective session:
WSPR activity worldwide was good, with 85 MF WSPR stations reported on the WSPRnet activity page at 0100z. Activity in North America has been reported to be down a bit and could be caused by the recent noise levels and coincidence of the Spring edition of the Stew Perry Topband DX Challenge, which tends to dilute the operator pool for both transmitting and receiving. Returning to receive duties after a bit of a hiatus is W5KCM, who I think is local to me here in the Dallas-Fort Worth area. He may be a member of the club that I am speaking at on Wednesday night, March 16.
Regional and continental WSPR breakdown’s follow:
There were no trans-Atlantic or trans-African reports during this session. UA0SNV, EA8/LA3JJ, and ZS1JEN were present according to WSPRnet but no WSPR reports were found in the database. A number of stations in Europe have been in contact with ZS1JEN. Andre is apparently working on improving his station so he can report stations while working on a kilowatt transmitter. This path seems more challenging compared to the path to Reunion Island where there is significantly more salt water in the path. The land path to UA0SNV is very long so I suspect with the proper attention to detail a system can be built that can hear and possibly be heard in Europe. It seems that EA5DOM might have a reasonable chance if his signal can get across western Africa. Much of the remaining path appears to be over salt water. Other stations likely have similar probability of being decoded.
In the Caribbean, Eden, ZF1EJ, is joined once again by Roger, ZF1RC, and both provide a number of reports to stations across North America, many reports being very early in the session.
In Alaska, Laurence, KL7L / WE2XPQ, experienced a good session with reports for the central US at WG2XXM and WG2XIQ. Curiously enough this time last year also yielded reports at WE2XPQ for my station. The opening continued for 3 or 4 days before disappearing again. Perhaps another repeat is in order.
In Hawaii, Merv, K9FD/KH6 / WH2XCR, experienced good band conditions with signals in North America but the path to Japan is cut off once again. Phil, VK3ELV, also saw the path to JA closed so its possible that local in JA storms are creating noise. While Merv was reported by John, VK2XGJ, the reciprocity in the path to VK4YB was missing during this session.
In Australia, Phil, VK3ELV, and Roger, VK4YB, received reports from WH2XCR. Phil also had late JA reports from the previous session. As previously reported, the JA path appears to be cut off during this current session, which is rare. Local storm in JA or VK may be preventing long term operation.
Jim, W5EST, provided a discussion on lightning protection yesterday. Today he continues in a similar thread entitled, “STATION LIGHTNING PROTECTION HOW-TO”. As someone who takes lightning strikes fairly regularly, I can’t express how important this stuff is:
“Today I’ll discuss the hardware side of station lightning protection in my own words and also with reference to Part 2 of a QST series on station lightning protection by Ron Block, KB2UYT in June-August, 2002. http://www.arrl.org/lightning-protection Tell us tips from your own experience for a future blogpost!
Recall from yesterday’s blog:
–Make an accurate, up-to-date block diagram of all shack equipment units showing all connections between blocks and indicate which are the top priority TX, RX or transceivers. Include any other electronic devices, showing connections between them, as well as every electrical conductor or conductive object within a few feet of a shack radio unit. Addition of LF/MF equipment has probably complicated your shack equipment unit arrangements, so this diagram is important.
–Draw a closed loop boundary around all the diagram blocks to reveal all of the lines going through the boundary to the edge of the diagram. Lightning-protect all such lines with line protectors grounded together.
Adding LF/MF transmitter equipment and an LF/MF TX antenna can introduce safety considerations (this blog Jan 15-16 & 18). Without attention on your part, 10 KV LF/MF TX antenna voltage could reach the HF side of your antenna farm and back to the shack in ways you didn’t expect.
Lightning. The way lightning sees it, every one of our stations provides an inviting three-dimensional circuit assemblage of relatively-low-impedance frequency-dependent impedances accompanied by a mobile blob of salt water (our human body). All of these are more or less coupled to earth ground directly or by spark gaps.
Suppose 100A– one-thirtieth of a small 3KA lightning strike– travels along 0.01Ω of a conductor or shield braid like coax, AC cord or USB cable in your shack. I2R tells us that’s 100 watts of heat dissipation. Suppose the pulse only lasted 100 microseconds, only 1/10,000 second, so no problem? But remember also that heat conduction away from a heating site would be nil in 1/10,000 second. The considerable RF content of the pulse would also squeeze much heat dissipation into the thin surface or “skin” of the conductor or shield. All of it leaves plenty of opportunity for mischief and damage.
On the potential difference side of the ledger, a lightning strike has plenty of voltage to reach into integrated circuits – even with their built-in electrostatic discharge protection ESD.
Coax cable protection is actually protection for expensive units to which the coaxial cable is connected. Include durable, effective in-line protector devices in the coax run. Bolt all the protector devices to one same plate. The plate connects via a short, straight wide strap to earth ground. Strap width exceeds the total of all coax cable circumferences entering shack. One more wide strap connects all shack TX/RX to the plate. Avoid L-bends in strap, use very gentle curvature to go around corners.
Open-wire/ladder line protection: Use equal-rated in-line gas tubes shunt-connected at the shack entrance. Current rating several tens of kA, and voltage rating ~ 1 KV. Voltage rating should be about double the highest coax voltage at maximum TX power and SWR. Gas tubes may be inadequate to protect a receiver directly connected to such lines.
Rotator control lines with relays can benefit from shunt protection, but non-relay electronic control circuits should have in-line protection.
Use in-line AC power protectors. Choose durable hardware that can protect from a lightning strike, not just mere AC line surges. Combine AC lines from lower power shack units into a single AC line going to one AC line protector. Separately AC protect a high power RF amplifier power supply. Separately protect one AC line to convey all AC from shack to outdoors.
In-line telephone/DSL line protection devices likewise must be sufficiently durable. Typical telephone connectors and phone-related PC boards are likely to be lost in an actual strike regardless.
All the above items share a copper wall panel to maintain all shack units at same voltage in every nanosecond of a strike. Physically ensure that cables on the protected side of the panel can’t get within sparking distance of conductors on the unprotected side. Keep cabling short and direct on the protected side to avoid stray energy pickup from the other side.
More tomorrow. Stay safe!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!