Enclosure

Here is this week’s space weather and geophysical report, issued 2018 Feb 26 0308 UTC.

Highlights of Solar and Geomagnetic Activity 19 – 25 February 2018

Solar activity was very low throughout the summary period. No active regions were observed on the visible disk. No Earth-directed CMEs were observed in available coronagraph imagery.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached high levels from 19-26 Feb. A peak flux of 13,500 pfu was observed on 19/2030 UTC.

Geomagnetic field activity ranged from quiet to G1 (Minor) storm levels due to multiple negative coronal hole onsets. Quiet to G1 (Minor) storm levels on 19 Feb were associated with peak wind speeds of just about 550 km/s from a negative polarity CH HSS. The geomagnetic response declined along with solar wind speeds with quiet to unsettled conditions observed on 20 Feb and quiet levels on 21 Feb . A subsequent enhancement in solar wind speeds from another negative polarity CH HSS increased geomagnetic field activity to quiet to active levels on 22 Feb, and further to quiet to G1 (minor) storm levels on 23 Feb, which were also associated with peak wind speeds around 550 km/s. Activity dropped to quiet to unsettled on 24 Feb and completely quiet by 25 Feb as effects from the CH HSS waned.

Forecast of Solar and Geomagnetic Activity 26 February – 24 March 2018

Solar activity is expected to be very low throughout the forecast period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at high levels on 26-28 Feb and 18-24 Mar due to elevated wind speeds from multiple coronal holes. Moderate levels are anticipated on 15 Mar and the remainder of the forecast period is expected to be at normal levels.

Geomagnetic field activity is expected to reach G1 (Minor) geomagnetic storm levels on 26 Feb and 18 Mar. Active levels are expected on 14 Mar, 16-17 Mar, 21 Mar and 22 Mar. Unsettled levels are expected on 27 Feb, 15 Mar, and 23-24 Mar. Quiet conditions are expected for the remainder of the forecast period. All elevations in geomagnetic activity are anticipated due to multiple, recurrent CH HSSs.

Don’t forget to visit our live space weather and radio propagation web site, at: http://SunSpotWatch.com/

Live Aurora mapping is at http://aurora.sunspotwatch.com/

If you are on Twitter, please follow these two users: 1. https://Twitter.com/NW7US 2. https://Twitter.com/hfradiospacewx

Check out the stunning view of our Sun in action, as seen during the last five years with the Solar Dynamics Observatory (SDO): https://www.youtube.com/watch?v=zXN-MdoGM9g

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In Episode #212 of Linux in the Ham Shack, the hosts take an in-depth look at the origins and operation of Slow-Scan Television (SSTV) and the Linux-native application QSSTV which allows radio amateurs to enjoy the wonder of sending and receiving still images via radio waves. Thank you for listening and stay tuned for a special episode on the use of the QSSTV picture editor which aids in the generation of SSTV images.

73 de The LHS Crew

Ham College episode 38 is now available for download.

General Amateur Radio Exam questions part 9. Digital Modes pt 1, Grounding.
54:03

Download
YouTube

High voltage indeed

The Meter on my Heathkit HW 101 stopped displaying ALC (dropped down to the negative stop).  So, I opened up the old rig to have a look. I found that the B+ voltage was reading 33 volts higher at one of the test points than it should. Ultimately that voltage didn't turn out to be the problem with the alc meter instead the meter switch had become dirty and needed to be cleaned. But in the process it got me to studying the way voltage is regulated in the Heathkit and I learned a bit about voltage regulation tubes like the OA2 used by Heathkit.

OA2 tube

OA2 in action at the right rear of the Audio board, notice the glowing gas inside

More Glow...

Look at the pretty violet glowing gas in the OA2

The OA 2 is actually not a vacuum tube it contains a gas that ionizes and in the process of ionization acts as a voltage regulator.  In a vacuum tube, if you see glowing gas inside the tube that means it's leaking and has become "gassy", that's a bad thing.  In the case of a gas filled tube like an OA2 you expect to see glowing gas and if you do not, then there's a problem.

In this case The OA2 regulates voltage to 150 volts and current is limited by the two high-wattage resistors connected in circuit to that tube (seen beside the OA2 in the photo above). Those resistors are dissipating a lot of heat.  I measured over 300F degrees with my IR temperature gauge (ouch).

Tube Testing without a tube tester?

I emailed one of the members of my local club, Joe WA4GIR to ask about tube testing and he sent me the following,  which he gave me permission to post:

The lack of a tube tester is not a limitation.  You can tell a lot about a tube test by looking at the voltages in the circuit.  If the filament goes out, the tube is dark and does not conduct.  That one is pretty obvious.  If the tube cathode loses it's ability to emit electrons, the voltages dropped across the cathode resistor and any resistors in the plate or screen grid circuits will change (the voltage drops across those resistances will drop).  A good tube tester will measure the ability of the tube to vary the plate current for changes in grid voltage, and you can see this with a scope by looking at the AC voltages on those elements, at least for the audio circuitry.  Probably not so much for the RF circuits as you are affecting the circuit when you probe it.  The best way to check for a suspect tube is to replace it with another.  I have 0A2's new in the box.  I may have the other tubes pulled from radios but it takes longer to look through those as sometimes the numbers are hard to read.  Hint. to bring out a faded number, rub it on the hair on the back of your neck-- better if it's oily.

A lot of resistors in old tube-type radios were 20% tolerance so don't expect the voltages to be that precise.  Tube rigs had much more variability than modern solid state circuits.  For the unregulated voltages, the precise voltage will depend component tolerances, tube health, and line voltage.  The line voltage here is about 125 when where I lived in Raleigh it was around 110.  You can do the percentages but that alone will account for some of the variation you might see.  I don't think that any of your tubes were damaged by overvoltage.  If they are drawing too much current, they will get hot, and in severe cases, the plates will glow red.  That's a concern.  Much less than that, the life might be reduced but I don't think you will see any short term effect.  When I've run tubes too hot, you might see signs of the tube going gassy, which is indicated by a blue low in the space inside the tube that is supposed to be a vacuum.

If you want to see the plates of a tube glow red, operate the final mistuned so it is drawing too much current.  They will glow red, haha.

The voltages out of the 0A2 are different -- they should be held pretty closely to 150V. I don't know the exact tolerance.  It might be a few percent.  So in your radio, 150V supply and any that are derived from it are the only ones that would have a  tighter tolerance.  The 0A2 has an operating current range of 5 to 30ma, and an operating voltage of 150V.  The supply voltage should be at least 185V to get the tube to "fire" but once "on", the voltage feeding will drop to the 150V level and be regulated there by the action of the tube which causes the voltage drop across to change (like zener diode regulators).  The regulation comes from the fact that a very small increase in the voltage across the tube results in a significant increase in the current so the resistor values are chosen so that the current through the tube remain in the 5 to 30ma range as the input voltage and the current draw of the regulated circuits varies for whatever reason.  Remember the current draw when you first turn on the rig will be low because the tubes don't conduct until the cathode gets heated so the designer must account for that in the selection of the input resistors to that circuit.

More to learn about hollow state

Welcome to the fourth edition of The Weekender version of Linux in the Ham Shack. In this episode, the hosts discuss the best cheese in the world, how "terrific" the podcast is, a young and complex single-malt Scotch, Hamvention 2018, W5MOO upgrading to General Class and much more. They even threw in a great old(ish) song by Paul and Storm. Hope you enjoy and have a great weekend!

73 de The LHS Crew