All indications are that the band was OK last night but many transmitting stations continue to be stuck in dry dock as unpredictable and inaccurate forecasts rule the night. For the stations that continue to receive and transmit through this difficult period, thank you.
Geomagnetic conditions have been a little more active but the storm levels that were expected have not yet manifested beyond elevated solar wind velocities with persistent speeds above 500 km/s. The North-pointing Bz appears to be contributing to the inability to reach storm levels.
Phil, VE3CIQ, reports that he decoded four stations and was decoded by eleven unique stations during this session. Transcontinental reports from WH2XGP in Washington state were also noted.
Ken, SWL/EN61, in Indiana was a victim of the low activity during this session, reporting only 80 decodes for the overnight session.
Neil, W0YSE/7 / WG2XSV, reports that he made it to Alaska over night in spite of recent, interesting band conditions:
John, WG2XKA / WA3ETD, reports good two-way transcontinental reports with Larry, W7IUV / WH2XGP, have returned after a hiatus:
With Field Day 2016 approaching rapidly, I asked the question on the 600-meter research group about whether any others in the group wanted to participate in another Field Day activity this year. Here is an except of that post:
I heard from Frank, K3DZ / WH2XHA, who indicates he will operate QRSS3 on 476.7 kHz during field day if the weather cooperates and can be trusted over night. If there are other interested parties, please let me know. I will be putting together a press release on or near June 1 and will post an updated page on this website with any additional participating operators.
Jim, K9JWV, of Utah, filed his Part-5 application yesterday and has been issued the call sign WI2XJG as of this morning in record time. Hopefully his time-to-grant will also be short. This may also be a clear sign that we are making progress with ET15-99.
Vinny, DL0IL, posted details and pictures of his portable operation from his team’s field day site:
Vinny notes that Wolf, DF2PY, was the last QSO for the event and every one returned home safely after packing up the site. Additional pictures of the event can be seen at https://www.facebook.com/media/set/?set=a.1071290752918939.1073741837.181587651889258&type=3
Wolf, DF2PY, reminds operators worldwide that the ON4KST chat/logger is a great place to make schedules for QSO’s when the band is in the summer doldrums. All are welcome! Thanks to Alain, ON4KST, for making this tool available.
Regional and continental WSPR breakdowns follow:
There were no WSPR reports from the trans-Atlantic or trans-African paths. UA0SNV and ZF1EJ were present but no reports were found in the WSPRnet database.
Laurence, KL7L / WE2XPQ, had a reasonable session for this time of year under the current propagation conditions. It wont be long until it won’t actually get dark at his QTH. In years past the path between Texas and Alaska has found some consistency during the North American summer.
Under the circumstances, Merv, K9FD/KH6 / WH2XCR, had a pretty good session, with continued two-way reports with VK4YB. John, VK2XGJ, wrote early this morning to say that the path was not looking good but managed to achieve a near-detection limit reception during the session. The path to the Pacific Northwest and southwestern Canada in addition to Alaska remain in tact. Given the recent return of the transcontinental path on the mainland I am curious to see if the path between Hawaii and the central US has returned.
Jim, W5EST, presents a topic that is of particular interest to me as a fanboy of the GW3UEP amplifier design, with this offering on the topic of non-linear amplifiers entitled, “630M CLASS C/D/E AMPLIFIERS”:
“On HF, hams often use a linear amplifier because nonlinear amplification would distort single sideband (SSB). Then digital modes are handled by supplying them in audio form as if they were audio input for transmission as SSB. Unfortunately, linear amplifiers inefficiently dissipate power.
By contrast on 630m, especially in the 7 KHz 472-479 KHz band awaiting FCC approval for Part 97 hams, the 2-3 KHz bandwidth of SSB occupies too much space and demands about +0 dB SNR in a 2.5KHz noise bandwidth.
Consequently, digital modes and CW are likely to rule 630m. Most of these modes can be generated by efficient nonlinear amplifiers without distorting the modulation. Practical 630m antenna systems are necessarily less efficient than HF antennas, so why sacrifice 630m transmitter efficiency in the shack?
Instead, says this train of thought, drive a good 630m transmitting antenna system with a nonlinear amplifier. Get more transmitter power output (TPO) from the power supply’s input to the final. Put up the best 630m receiving antenna system you can, too.
What types of nonlinear amplifiers are there, in terms of the principle of operation? Several! Their efficiency is high at two levels. First, when a power amplifier (PA) device is off (current I =~0), dissipation P = V I = (V x 0) = 0. When a power amplifier (PA) device is on, it’s full on so the voltage across it is near zero (voltage V=~0). P = (0 x I) = 0 when the PA is on.
Class C amplification feeds a 630m sine wave to a power amplifier that is sufficiently biased that it delivers a pulse once per 630m cycle. Since a pulse contains lots of harmonic content, a tank circuit or filter tunes the output to keep unwanted frequencies away from your antenna system. Your outdoor 630m antenna tuning unit (ATU) further rejects them.
Class D (see endnote*) switches the analog input signal to create pulse width modulation (PWM) or pulse density modulation that’s more fully at work than Class C throughout each 475KHz 2 microsecond cycle. Then a PA-LPF (PA low pass filter) passes signal and rejects switching frequency and harmonics.
Class D uses a smaller heatsink because its PA is even more nearly full off or full on. Unlike Class C that effectively switches on once per cycle, Class D switching frequency is much higher (like 10x the 475 KHz signal frequency). That makes output filtering simpler and smaller.
Class E ** amplifier design even more fully confronts the challenge of getting PA voltage down to zero by each time the PA conducts. Class E artisans determine the right drive circuit and PA circuit inductances and capacitances so that economical FETs devices achieve remarkably low power dissipation in class E throughout the start, middle and end of transmission.
Do you have experiences you’d like to add, beyond what’s said in the cited web sites? Let us know!”
*https://en.wikipedia.org/wiki/Amplifier#Class_E (Scroll down 60%.)
http://www.gw3uep.ukfsn.org/100W_QTX/100WTX/100WTX_2july11.htm (Scroll halfway.)
VK1SV class-E design class for beginners. http://people.physics.anu.edu.au/~dxt103/class-e/
Sokal, N.O. WA1HQC. (2001) Class-E RF Power Amplifiers. QEX, Jan/Feb 2001:9-20.
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!