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2015 October 28-31
A dim view of M33, but you can see NGC 604
This is admittedly not a great picture of the spiral galaxy M33; I took it in
town, in a sky that had too much city light and some haze. But it shows clearly
the nebula NGC 604 (a compact bright spot toward the upper left), which is a great
nebula in the galaxy M33. As with other recent astrophotos, this was taken with
the 8-inch telescope at f/7. It's a stack of twelve 58-second exposures.
The Interstellarum Atlas, which indicates the relative visibility
of every object, brought to my attention this neglected galaxy, NGC 6946,
which is on the Cepheus-Cygnus border. (Yes, the constellations have official
borders, adopted by international agreement back in the 1920s.)
As you can see, NGC 6946 is a fine sight. It's neglected because so many
other interesting objects are in the same area of the sky, and also because
dust in our own galaxy dims our view of it. (Indeed, one of the thickest
parts of our galaxy runs right in front of it — the Cygnus Milky Way.)
If not for the dust, this would be
one of the four or five brightest galaxies in our sky.
Stack of fifteen 58-second exposures, same setup as the other astrophotos
on this page.
This is one of the many nearer objects
in Cygnus that draw attention away from NGC 6946.
This nebula is, of course, in our own galaxy.
It is a shell of gas emitted by a star. Some say it looks like an Euro symbol
upside down and tilted. Stack of nine 58-second exposures.
Tapping or knocking noises from Celestron AVX mount
During last week's astrophotography marathon, a mechanical problem with my
AVX mount appeared and gradually worsened. It was a tapping noise, about
0.5 to 2 seconds between taps, with the interval somewhat varying, and was
present only during RA tracking, and, initially, only with the telescope aimed
in certain directions.
It progressed until it was almost constantly present, correlated with visible
jumps in the tracking (maybe 2 arc-seconds in amplitude, which is not a lot, but
visible at high power and very disturbing to an autoguider), and able to be felt
as vibration. It also correlated with a fluctuation in the brightness of the display
on the handheld controller, indicating DC power consumption was varying with it.
I removed a cover (after someone at Celestron told me to; not before, or it might
have voided the warranty), and, feeling for the source of the vibration,
found that it seemed to be coming from
the gearbox marked X or maybe λ
in this picture:
My contact at Celestron says it's an infrequent but known mechanical problem with that gearbox, and
they've had me return the mount under warranty. I'll let you know how the story unfolds.
[Update, 2017:] I have been told that in many cases the mechanical problem can be corrected
by just pushing the brass gears toward the gearbox a bit. I've heard from someone who
does this to his AVX every year or two. I haven't tested this theory myself.
Further, everyone should note that
tapping or knocking sounds from equatorial mounts are not necessarily a problem.
Many mounts make them all the time and track perfectly.
There are several sources of tapping sounds, one of which is thermal expansion and
contraction of the plastic housing; you've probably heard similar sounds from
heaters when they were first turned on.
Don't assume you have a problem unless you can link it to a problem with performance.
How do you like that bright-orange brake knob?
Celestron brake knobs are normally black. The paint on mine got scratched, and I decided to
repaint them with something more visible.
This hasn't changed much, if at all, since the last time I posted pictures,
but here is what my telescope-camera setup looks like.
The main telescope is a Celestron 8 EdgeHD. On the back of it is a Celestron 0.7x (f/7) reducer
and behind that, a Canon 60Da camera. The upper telescope is an Orion Shorttube refractor
(80mm f/5) used as a guidescope, and at the back of it, an SBIG STV autoguider camera.
All this sits on a Celestron AVX mount, which has the ability to aim it at any part of the
sky and track the earth's rotation so that the object being photographed will hold still in
the picture.
How much did all this cost?
I built it up over years, but let me just say it costs less than a year's membership at an
average country club, and certainly much less than a car
or boat.
Oh, yes, about those cords: Obviously there's a power cord to the telescope mount,
and a cord connecting it to its handheld control box (which you see in its holder),
and a cord to the autoguider camera. What are the rest of the cords? Well, both the main
telescope and the guidescope have Kendrick dew removers, which are heating elements that
slightly warm up the front lens to keep dew from forming on it. And the camera is connected
to an interval timer which tells it when to open and close the shutter.
How it all works: Naturally, the main telescope takes the picture. The guidescope and
autoguider deal with the fact that, by itself, the motor in the mount does not track the sky
perfectly. The two main reasons for this are: (1) the axis of the mount is not perfectly parallel
to the axis of the earth (although I can get it to within about 1/20 degree); (2) the motor and
gears are not perfectly even. So the autoguider camera watches a star through the guidescope
and sends signals to a computer which, in turn, tells the telescope to nudge itself a tiny fraction
of a degree (typically 0.5 arc-second) in the desired direction.
The mount contains a computer, too. Contrary to what many people think, the mount doesn't
need a computer to track the sky. All it needs it a motor running at the right speed and an
axis aligned with that of the earth. Then it only has to do one motion. Telescopes did this
in the 1890s with wind-up clockwork-driven motors.
The computer provides
various kinds of remote control (such as autoguiding)
and, most importantly, contains a library of celestial objects and
can find them by position (once I show it 4 known stars at the beginning of the session, so that it
can get oriented and measure its own error).
That's what the computer accomplishes.
As you might imagine, it is vitally important for the guidescope not to bend relative to the
main telescope. It doesn't have to be aimed in exactly the same direction, but the difference
between the two, whatever it is, must not change during the exposure, because only the guidescope
is actually tracking the star. The main telescope is just assumed to be tightly coupled
to the guidescope. Astronomers call this the problem of differential flexure.
My solution includes an extra metal support for the autoguider camera (so it's not just held
in place by the eyepiece holder into which it fits) and zip-ties so that nothing can tug on its
cable (or rather, so that if anything does, it will move the whole system, not just the guidescope).
To come: I've already started experimenting with using a much lighter-weight camera for
autoguiding, connected by USB to a laptop running PHD2,
in place of the STV Deluxe autoguider and control box.
I am also going to experiment with a smaller guidescope.
The tiny "piggyback autoguider" that I built a while back is not
quite precise enough — apparently — but the 80×400-mm guidescope
that I use now is so heavy that it introduces its own risk of flexure.
Regardless of the size of the main telescope, experts now agree that a guidescope with a
focal length of about 200 to 400 mm is sufficient to track the stars as accurately as
the steadiness of the air normally allows.
The secret? Sub-pixel accuracy. The autoguider measures how the light from a star is
spread across four or more pixels. It then calculates its position to an accuracy anywhere
from 1/5 to 1/20 pixel.
Latest on the vintage Hallicrafters radio: I've replaced all the electrolytic capacitors
and all the wax paper capacitors that have a wax exterior. Those that are plastic-encased are
slated for replacement but haven't been done yet. I keep finding signs of kluged repairs done
by someone in the late 1950s and have even encountered a couple of broken wires, or at least
broken solder joints, as well as one capacitor that was the wrong value.
(Now the tone control goes high-medium-low instead of high-low-lower.)
But I've only replaced two tubes and will not replace more unless they turn out to be weak.
The reason? Tubes wear out with use, but capacitors deteriorate with age. In rarely-used old radios,
capacitors are more failure-prone than tubes. The other failure-prone parts are the power cord,
various connectors, and potentiometers (controls such as the volume control).
It seems to work a little better every time I work on it.
Tonight I listened to Radio Romania International, in Bucharest, on 7.3 MHz
using an antenna that was just six feet of wire, indoors, in my foil-insulated house.
Neither of these nebulae is actually shaped like a dumbbell; each is actually
more like a semitransparent doughnut seen edge-on.
Each is a planetary nebula, meaning it consists of gas thrown off by a dying star,
which continues to shine in the middle and illuminates it.
(The Ring Nebula is the same kind of thing seen face-on.)
This is M27, the Dumbbell Nebula,
a stack of 16 58-second exposures with the same equipment as in several recent entries:
And here is the "Little Dumbbell," M76 in Perseus, appreciably farther away and
harder to see. This is a stack of 10 58-second exposures.
More pictures with the 8-inch telescope in my driveway.
Here you see the great globular star cluster M2,
which I don't think I've photographed before and still
haven't photographed really well. This was taken on October 19,
and a problem with my telescope drive was starting to
manifest itself; more about that later. This is a stack of
ten 58-second exposures, Canon 60Da, ISO 3200, f/7.
And here is M71, a relatively small and sparse globular cluster
that was once thought to be an open cluster.
Stack of eight 58-second exposures.
The Double Cluster is a pair of star clusters in the constellation Perseus.
In the past I've photographed both
of them in a single wide-field view with a telephoto lens.
Here, however, are separate views, taken with an 8-inch telescope (Celestron EdgeHD
with f/7 compressor) and Canon 60Da. These pictures were taken in town, with the moon in the
sky, so it's surprising they look as good as they do.
First, NGC 869, a stack of 16 58-second exposures:
And then NGC 884 (with some prominent red stars), a stack of 12 58-second exposures
in bright moonlight:
I have a backlog of astrophotos to show you, but let's start with two of the sharpest
moon pictures I've ever taken. These were taken on consecutive evenings, October 20 and 21,
with a Celestron 8 EdgeHD telescope, f/7 compressor, and Canon 60Da camera body.
Each is a single 1/320-second exposure at ISO 500 or 400 respectively.
They were slightly sharpened digitally, and color saturation was raised.
As you can see, the wide, flat field of this optical system produces a picture of the moon
that is sharp from edge to edge; most astronomical telescopes are sharp only in the center.
Sadly, the full face of the moon does not fit on the camera's APS-C sensor.
I am experimenting with autoguiding the modern way, using my monochrome planetary camera
connected a laptop connected to the telescope.
There are two very good free software packages for the purpose,
Stark Labs' PHD Guiding
and its new, more full-featured open-source derivative,
PHD2.
For either one, you have to have an ASCOM driver for your
telescope. I'm using "Celestron Telescope Driver," which is
newer and better than "Celestron Scope Driver."
(Download the ASCOM platform and also the telescope driver; install both.)
I had no problem at all getting the original PHD up and running.
It supports my
ImagingSource DMK 21AU04.AS camera natively.
(Ignore the word "Firewire" in the menu item; it works just as well with a USB camera.)
PHD2 doesn't. I was able to get it working in the following way:
(1) Choose "OpenCV webcam" and connect to it. (I got better results than with "Windows WDM.")
(2) Curiously, I had to open the camera dialog, change a few settings (like auto exposure),
and then change them back to what they had been and click OK. Until I did this, in loop mode
I got alternating
frames with very different exposures (under- and overexposed).
This problem was even worse with "Windows WDM."
(3) Click on the "brain" icon and tell PHD2 that the camera has 5.6 micron pixels and needs
a calibration step of about 500 milliseconds. Until you do this, it thinks your camera has
incredibly tiny pixels and will not calibrate successfully.
I would still like to see native support of the ImagingSource cameras in PHD2.
Hallicrafters update: Fixing another 50-year-old problem
I've done a few more repairs to the vintage Hallicrafters radio, and, to my
surprise cured a long-standing problem.
Until just now, whenever it was set to "Standby" the radio would emit occasional
static-like noise through its speaker. I thought that was normal.
The "Standby" switch uses the AVC system to bias all the RF and IF amplifier tubes
to very low gain. I figured some noise was still getting through.
Presumably, the static-like noise was also present while listening to the radio,
just not noticeable because of the other static that is genuine.
Two nights ago (Oct. 18) I replaced the 5Y3GT power rectifier tube with a new
Russian-made elektronnaya lampa...
...and replaced the 6SK7 IF amplifier tube whose locator pin was missing with a new
English-made one with the pin intact. (In case you're not familiar with octal sockets,
the round prong in the middle of the base has a ridge on one side that fits into a slot
in the socket, to ensure that the tube goes in the right way.)
I also finished reworking the AC power inlet, adding capacitors to bypass the power
line to ground, and I replaced the cathode resistor of the aformentioned ill-fated
6SK7.
And the radio works better than ever, and the static-like noise on "Standby" is gone.
I don't know which component was responsible for it. Quite possibly the 6SK7 itself.
Still to come: Replace one remaining electrolytic capacitor (in the audio section) with
a modern one; replace all wax-paper capacitors with modern ones; replace volume control
(which is very noisy); clean contacts; and, assuming I find nothing else needing
attention, do a full alignment.
Merope (pronounced Mer-o-pee) is one of the stars in the Pleiades cluster,
and next to it is the first part of the Pleiades nebulosity to have been
discovered. In a long-exposure photograph, all of the nebulosity has a strangely
streaky texture, caused by magnetic fields acting upon the dust particles that
constitute the nebula.
This is a stack of ten 58-second exposures through a Celestron 8 EdgeHD telescope
and f/7 converter (0.2 meter aperture, 1.4 meters focal length), taken with a Canon
60Da at ISO 3200 under rather poor conditions, with the Pleiades low in the sky
and lots of small-town light reflecting in the sky. A much more striking picture
could be taken out in the country.
Here is the star cluster M34, photographed with the same setup, a stack of nine 58-second
exposures. This cluster is a fine sight in binoculars or a small telescope, but it almost
needs a smaller telescope than what I photographed it with.
How do you like the guiding in this wide-field picture of the Cygnus Milky Way?
There wasn't any guiding. This is a stack of one hundred 2-second exposures from
a fixed tripod, with a Sigma 50-mm f/2.8 lens wide open and a Canon 60Da at ISO 3200,
calibrated with dark frames, flats, and flat darks, and stacked with Deep Sky Stacker,
taken under a moderately bright in-town sky where the Milky Way was barely visible.
After processing, it was adjusted with PixInsight, but GIMP or any other picture editing
package would have done the job.
To do this kind of astrophotography, all you need is the camera. The software is free.
Here's a field in Aquila, done the same way, a stack of 106, count 'em, 106 exposures.
You can see Barnard's E, an E-shaped dark nebula to the right of center that I have several
times photographed at higher magnification.
Prepare for the floodgates to be opened — I have plenty of material for the
Daily Notebook, including a flurry of astrophotos.
First item: the Peach State Star Gaze. This year I attended only one afternoon of
the week-long amateur astronomy convention, but I had heard two good talks
(which would have been better without secondhand smoke in the lecture tent;
I don't know where it was coming from).
Rod Mollise spoke on
"Amateur Astronomy the Old-Fashioned Way," by which he meant visual observing
with a non-computerized telescope.
He advised would-be visual observers to adopt projects, develop lists of objects
to look at, learn to sketch, and avoid the "M13 syndrome," which is what happens
when you get your telescope out, look at half a dozen very familiar objects that are
the same each time, and put it away again, slightly bored.
On a technical level, he points out that the standard for eyepiece apparent field of view keeps
increasing. It used to be 40 degrees. My eyepieces today have 60-degree fields, but
good eyepieces with 100-degree fields are available from Explore Scientific and others
(as well as superb ones, at higher prices, from Tele Vue). They are a boon with
non-computerized telescopes because it is much easier to get the object in the field
of view if the field of view is wide.
Dan Llewellyn spoke about the Sony A7 series of mirrorless ILCs (interchangeable-lens
cameras), especially the A7S.
A while back I opined that it might be the up-and-coming astrophotography
camera, and it up and came!
The price has fallen, and meanwhile,
test results have confirmed that its performance in dim light is head and
shoulders above other cameras (note the 9 stops of dynamic range at ISO 12,800,
and see also this).
The price of the A7S has been cut, and a successor, the A7S II with image stabilization,
has been announced.
More amusingly, how do you build a good astrocamera these days? Not from scratch, but by
taking apart a Sony A7S, moving the sensor forward, adding a cooling system, and adding
a Canon lens mount (!).
I'm not kidding. CentralDS,
in Korea, is doing it.
The A7S isn't perfect. According to these
notes and the link from them, it has rather poor hydrogen-alpha response if unmodified, and it has a
"star-eating" noise removal algorithm (less heavy-handed than Nikon's infamous early one).
In sum, the A7S is 4 times as sensitive to light as the Canon 60Da. That is accounted for by doubling
the quantum efficiency (about 65% vs. 35%; perfect would be 100%) and doubling the area of the pixels.
What's extraordinary is its lack of noise, especially read noise, and its high dynamic range.
I hope the whole digital camera industry moves in this direction.
Dan is of the opinion that innovation at Canon has slowed down or stopped and Sony has moved to the head
of the pack as a developer of CMOS image sensors. He may be right.
My understanding is that Sony also makes the sensors for Nikon and several other brands.
Before we catch up with astronomy, here's something about politics that has been rattling around
in my head for several days.
This CNN editorial
makes some observations about how special-interest groups can suddenly lose political power.
Never mind that the author thinks this is about to happen to opponents of gun control;
let's look at the process and the examples.
His examples are the Cuban expatriate lobby, which opposed normalization of relations with Cuba
for years; the Anti-Saloon League, long defunct, which gave us Prohibition and nothing else;
and especially the tobacco industry, whose political power collapsed rather suddenly in the 1990s
after a long preliminary decline.
Going beyond the author's observations, we can extract a generalization:
Special-interest groups lose power when the public begins to feel that they are denying
reality.
The crashing moment for the tobacco industry was when executives testified before Congress
that they did not believe cigarettes were addictive. Cue cuckoo sound effects — the whole
audience, their supporters as well as opponents, must have seen this as a desperate attempt
to deny reality.
Another force acting against Big Tobacco was the increasing frustration of people of my generation
and younger who were tired of breathing secondhand smoke.
Respecting nonsmokers' airspace was basic etiquette in 1930 (hence the long tradition of
smoke-free railway cars), but it was dead by 1955, and the etiquette books were asserting
that even nonsmokers must provide ashtrays and welcome people to smoke everywhere.
Cough, cough. A lot of us saw that as denial of reality and of common courtesy.
For the Anti-Saloon League, the crash came with the Great Depression. The League's premise
was that, for a while, we could ignore all political problems except alcohol. That rang thin
even as a temporary platform, and the Great Depression made it completely unrealistic.
The League was seen as denying reality.
For the Cuban expatriates, it was the fond hope that Castro's revolution might yet fail,
even after half a century of stability. It became harder and harder for anyone outside a small
community to believe this. We're normalizing relations with Cuba in spite of them.
That doesn't mean supporting Cuba, only admitting that they have a stable regime.
What about the "gun lobby," which the editorialist, mistakenly I think, equates with the NRA?
My advice to advocates of responsible gun ownership would be: Don't stick together quite so
closely. Don't rush to support every pro-gun voice, even the nutty ones.
Weed out the gun advocacy that is tied to bad citizenship, and above all, never sound as if you
are taking up for the perpetrators of a crime, even indirectly.
Dividing everyone into "antis" and "pros," as
two monolithic sides in a battle, won't do. Admit, clearly and loudly, that some people like guns for
the wrong reasons and can't be trusted with them. Otherwise, you're denying reality.
Fixing a 50-year-old wiring error
(Hallicrafters S-40B AC power inlet)
[Revised.]
Latest news on the Hallicrafters:
Ever since my father bought this radio secondhand in 1965, it had had a "hot chassis" problem:
touching the switches would occasionally give you a tingle of electric shock,
even though the radio has a power transformer and should be fully isolated from the AC line.
In the 1980s I installed a polarized power cord, but it recently came to my attention that the
tingle problem wasn't solved. Some careful testing revealed that it would drive as much as
2 mA of alternating current through whatever came between itself and true ground.
("Whatever" in this case wasn't me, it was a multimeter!
The hazard to humans was much less because a human would rarely be in contact with a
good ground separate from the radio.)
OK, time to analyze the circuit. This is the AC power inlet — that is, the circuitry from
the power cord to the primary of the power transformer — as Hallicrafters claimed to
have built it:
(This isn't the whole radio, only a small part of it. I've had one puzzled inquiry...)
By the standards of 1954, the design is not bad. The capacitor provides RF coupling from the
power line to the chassis, helping to improve the effectiveness of the chassis as a shield.
My 1980s-vintage polarized cord ensured that the switch was in the "live" side of the line,
and the capacitor should have been on the "neutral" side, at most a couple of volts away from
ground. So where did the 120-volt tingle come from?
Well... one thing I've been noticing is that some capacitors in this radio must have
been replaced before we got it in 1965. Capacitor technology was advancing rapidly during
those years, as wax gave way to plastic, and some of the capacitors look like they date from
the 1960s rather than the 1950s. Some of them even have spliced wires.
But I didn't replace them, and if my father had had the radio repaired, I think I would
have known about it. Someone must have replaced them before 1965.
In fact, the capacitor in the diagram above had been replaced. I could see wax from the
old wax capacitor that had been in its place. And the new one was not only a different
capacitance, but also installed in the wrong place! Here's what I found:
The "live" side of the line is connected to the chassis — through a capacitor,
thank goodness, but connected — when the switch is on. Ouch!
Well, then, let's fix it. I thought about going back to Hallicrafters' original circuit,
but no, one thing I always do with older equipment is bring the AC inlet up to modern
standards. This is a piece of equipment designed to be connected to others (if only
through the headphone jack). It therefore deserves a 3-wire power cord with a truly
grounded chassis. Here's what I'm building:
I will use capacitors that are rated to be safe to use across the AC line (Y2 rated).
Those aren't there yet. The rest of this has been built and I'm listening to
Radio Havana on it right now.
Today is Columbus Day in the United States, on which we close our banks and
post offices in honor of Christopher Columbus' 1492 discovery of America.
Columbus was not the first European to land in America — that was a Viking,
if not someone even earlier — but Columbus was the first to establish
permanent contact. Obviously, his place in history is important.
But there are two blemishes on his record.
(1) Christopher Columbus never realized he had discovered a new continent.
All his life long, he thought he had found islands near India.
That's why America isn't named after him.
We use the name "Columbia" here and there, but America is named after Amerigo Vespucci,
the geographer who figured out what it is!
(2) Columbus did so badly as colonial governor that he was put in jail in Spain
for brutality. Until recently, historians thought this was mainly a political dispute,
but a newly
discovered document substantiates the accusations.
Then there is Columbus' character. He considered himself a Christian missionary who
deserved to be rich — an odd combination — and engaged in slave trade.
For reasons like these, a number of people are in favor of re-designating Columbus Day as
Heritage Day or something like that. I see considerable merit in that.
Columbus was in the right place at the right time to change history, but there are limits
to how much we can revere him as founder of the New World.
By the end of his life, it was obvious to all his contemporaries that he was an
odd character with a mixed record.
Readers with long memories will recall that my Hallicrafters shortwave radio
failed back in 2008.
My mills grind slowly, but they do grind, and today, October 11, 2015, nearly eight years later,
I got around to starting the repair. I had ordered parts a few months ago.
If that radio looks half naked, it's because my mother mistakenly threw away its outer
enclosure around 1979. Someone on eBay wants $50 for the missing enclosure. I offered
him half of that and was turned down...
But the obvious problem with fixing this radio is that if you turn it upside down, it
would rest on its tubes, not a good idea.
A couple of bar clamps take care of that:
The symptom back in 2008 was that one of the resistors feeding power into
the main electrolytic filter capacitor had burned up rather dramatically.
(Picture here.)
I diagnosed a shorted filter capacitor and, after confirming that it had not
taken out the power transformer during its demise, proceeded to replace the
capacitor and the resistors in its circuit.
The original capacitor was a tall can containing three electrolytic elements with
a shared cathode. To avoid leaving an awkward hole in the chassis, I left it in place
but disconnected it. In its place are three modern capacitors on a terminal strip,
together with modern resistors:
And then, with Melody watching (I always want someone with me when doing high-voltage
work), I applied power. The pilot lamps lit up, but there was no sound in the speaker.
The B+ voltage measured zero.
I guessed that the rectifier tube (a 5Y3GT) had failed, and sure enough it had; when I took
it out, there was a broken heater filament flopping around in it.
Fortunately, I had a replacement on hand, a big imposing 5U4GB.
Next try — and here's where it becomes worthy of The Twilight Zone.
I applied power again, and this time the cathode resistor of an IF amplifier started
to burn up, quite visibly!
Cathode resistors don't normally carry heavy current.
So how was it doing that?
Cue Twilight Zone music...
I took a good look at the IF amplifier tube, a 6SK7, and noticed that it was an
octal tube with its central plastic prong broken off, the prong that makes sure it's
inserted in the socket the right way.
On close examination I could see how the prong used to be oriented...
and in fact had observed this some years ago, and made a mark on the base of the tube...
and then I looked at the iPhone photo I had snapped before pulling the tube out.
The tube had been in the socket the wrong way!
It was rotated 1 step from where it should have been.
Specifically, the heater (which is the only low-resistance part of the tube)
was effectively shorting what should have been the anode to what should have
been the suppressor grid and cathode.
How it got that way, I have no idea. I could have sworn that when I turned the radio on
in 2008, it had been left untouched since being put on the shelf in working order
a few years earlier.
I put the tube in the right way, and even without replacing the cathode resistor,
the radio worked.
The cathode resistor must not have changed in resistance too much as it emitted
some smoke.
Naturally, I'm going to replace the resistor and the tube, and several other things;
for instance, this 60-year-old radio needs a new volume control and a proper 3-wire
power cord.
The repair will proceed. As I told Melody, this is a repair, not a "restoration."
I'm not trying to put it into authentic 1954 condition.
Some improvements that I've made over the years, such as conversion to 8-ohm headphones,
will remain in place.
Some battle scars, such as the little piece of the dial plate that was already missing in 1965,
will remain as they are.
I don't actually need this radio (my 1987 Sony ICF-2010 performs far better), but I want to
honor my father's giving it to me (50 years ago) and keep it usable.
Now for some technical afterthoughts.
First: I verified that the twisted tube did not burn out the IF transformer in its plate
circuit. But it did make the cathode resistor emit quite a bit of smoke.
Doing a hurried test with a voltmeter, I found that that 470-ohm resistor was dropping 50 volts,
which means it must have been carrying
about 100 mA and trying to dissipate 5 watts.
OK, that's not a raging inferno, but it's enough to burn up a 1/2-watt resistor.
The resistance of the IF transformer was only 9.3 ohms.
That means it dissipated about 0.1 watt, probably enough to heat it up and do damage
if it had been allowed to continue for a long time, but for now, we're safe.
Second: Was the twisted tube the whole problem?
Was it that, and not a shorted
electrolytic capacitor, that overloaded those resistors?
Maybe so!
I assumed the electrolytic capacitor had burned out and taken all the resistors
with it; but I only saw one resistor that was definitely burned up, not
just discolored with age.
That resistor carries most of the power for the tube circuits and is
rated at 1500 ohms, 10 watts. That tells us it is designed to carry
a maximum of 80 mA.
Adding 100 mA to that would definitely burn it out.
I don't regret replacing the electrolytic capacitors because at 60 years of age,
they're definitely due for it. In fact, I plan to replace all the other electrolytic
and wax capacitors in the radio; they are ticking time bombs.
But I may get to chalk this one up as one of the oddest electronic problems
I've ever fixed. All I can assume is that, when I was moving the radio, the
tube fell out of its socket and I mistakenly replaced it with the wrong orientation,
then happened not to turn the radio on again and discover the problem at the time.
This surprisingly good view of NGC 7331 and other galaxies is the result of an imaging
session that I didn't think was going well.
I set up the C8 EdgeHD on the AVX mount in my driveway last night (Oct. 7) and
took a series of 1-minute, or rather 58-second, exposures using the Canon 60Da at
ISO 3200 and f/7 (0.7×) reducer.
There was a flexure problem.
The autoguider reported excellent tracking, but not one of the images looked first-rate;
some were quite seriously smeared. Something was moving between the autoguider and the camera.
I never figured out what it was.
Nonetheless, a stack of the 24 best images was surprisingly good.
I used kappa-sigma stacking to discard highly deviant pixel values but average
the ones that were close to the mean.
This was taken in town, through a slightly hazy sky; M31 was not visible to the naked eye.
But the picture shows stars beyond 18th magnitude and galaxies beyond 15th magnitude
and has round 3-arc-second-diameter star images. Not too bad, if I may say so.
After four and a half years of hard use, the touchpad on my Lenovo laptop had become
shiny and slightly sticky in the middle. So, to a lesser extent, had several keys
on the keyboard, especially the space bar. It was hard to use the touchpad because
its texture was so different in the middle than near the edges; I couldn't move my
finger across it smoothly.
My first guess was that I needed to use an alcohol-based cleaner to remove grease
deposited by my fingers. That is a good thing to do regularly, but in this case it only
helped a little. The problem was that the surface had been worn very smooth,
so even when clean, the central area was so glassy that my skin would almost stick to it.
What worked? A very brief sanding with a fine-grit sanding sponge.
I thought I might be sanding the letters right off the keys, but no — I was just
roughening up what had been worn smooth. Although not as good as new, the keyboard
and touchpad are much better.
This is something to do just once, after 4 years of wear, not every day.
It would wear the plastic down if done even a few times.
But in this situation, it was just what was needed.
If you look at my writing, you'll see plenty of short, common words, even when I'm writing about a specialized subject.
I have about as big an English vocabulary as a person can have, but I don't dump it all on everybody all the time. That would be like a cook using all the spices in the rack in every meal. The result would not be pleasant.
More to the point, I want people to be able to read and understand what I write. I'm not trying to impress you by saying things you can't understand. Although I can say "obfuscation" and "intransigence," I seldom do. Rare words are seldom the best way to express an idea. That's why they're rare.
I don't hesitate to use "hard" words when needed. When I'm writing about something specialized, you'll see specialized words that pertain to my subject, but the rest of the language will be as plain and simple as I can make it.
Does this mean I'm "dumbing things down"? Far from it. "Dumbing down" would mean leaving out complex ideas or simplifying them so much that they are no longer accurate. Expressing complex ideas in simple words is the opposite of dumbing down. We all have a certain amount of brain power. I'd rather use it understanding things than decoding badly chosen words.
I don't want to sound sophisticated; I want to be exact. I want to think something clearly and
communicate it clearly to you. Simple words, when they are accurate, are best.
Simple language doesn't just protect you; it also protects me. If I keep things simple, I'll know whether I'm making sense. I've seen too many people get so busy piling up rare and specialized words that they think they're thinking deeply when they're hardly thinking at all.
The opposite of an error is usually another error.
You can fall off the horse on the left or on the right.
The two are very similar, and both are very different from
staying on the horse.
Discussing the events of recent days on Facebook, I've realized that I'm making some
people uneasy. I may not be conservative enough for them.
I've known for my whole life that I'm not liberal enough for certain other people.
I think for myself. If you read what I write, here or on Facebook, you will be
prodded to do the same.
I don't spend my time trying to prove that I am "perfectly conservative"
whatever that might mean, as if God were at the right-wing extreme of human politics.
The terms "conservative" and "liberal" only describe how you are positioned relative to
other movements at the time. They are not names of political philosophies.
The very same position could be considered conservative or liberal at different times
depending on what else is going on.
Reagan's politics was considered very conservative at the time; some of it is
considered liberal now.
I am a doctrinally conservative Christian, but this does not obligate me to follow the
political Right on every issue. Christian values have political consequences, but let's not
be suckered into following uncritically any political movement that pays lip-service to
some of our values.
And I am often mystified by the way positions on different issues are presented to me as
package deals. Do my positions on abortion, gun control, global warming, deficit spending,
the gold standard,
and apokatastasis (in theology) all have to be the same? Sorry, I don't see how these six issues
are tightly linked together. Yet some people don't consider me a good Christian unless
I say "no, no, no, no, no, no" (and others would insist that I say "yes, yes, yes, yes, yes, yes").
One principle I live by is to understand an opposing position before rejecting it.
That means I take a genuine interest in positions with which I completely disagree.
Seeing me do this scares some people. They think everything they disagree with is "enemy"
and when I listen to it I'm consorting with the enemy.
Some people say they have trouble understanding me when I'm weighing two or more
positions against each other, or trying to find a solution that is in between two
extremes, rather than just expounding a position they're already familiar
with. I apologize (not very sincerely) for any headaches that might cause.
Another principle is to pay attention to facts, not just ideologies.
Where both Karl Marx and Ayn Rand went wrong, in my opinion, is that they based their systems
on thought-experiments about imaginary human societies rather than real information.
The real world is full of surprises. And as I've said before, I don't want conservative
facts or liberal facts, I want fact facts.
I know at least a little about politics in countries other than my own.
That gives me a perspective that often goes beyond the American media.
And it really underscores the fact that different issues can be viewed separately —
the U.S. Democratic and Republican platforms are not the only possibilities.
I even reserve the right to change my opinion in the light of new information.
If you are a sheep — if other people do all your thinking for you — then this
is something you are not allowed to do, and it may scare you to see me doing it.
(No, I don't have any big upcoming changes to announce! But small adjustment of my opinions
is going on all the time. It's part of being alive.)
So I'll continue to think for myself, even if it scares people.
Maybe I'll prod some of them to think, too.
Afterthought: It has been pointed out to me that a strand in our popular culture —
something that often turns conservatism into a parody of what it ought to be —
is the notion that if you don't take the most extreme position, you're a coward,
you're "soft on" something that is viewed as the enemy.
Compromise, finding creative win-win solutions, and even trying to understand the other
side are viewed as signs of weakness.
It's as if life were a sport and your only job were to defeat the other team.
Some people are starting to argue that most American deaths don't involve guns at all;
those that do rarely come from mass shootings; so we should stop worrying about mass shootings
and work on public health or road safety. It would save more lives.
That misses the point. What needs saving is not just lives, but civilization.
A mass shooting terrorizes far more people than its immediate victims. Tolerating
mass shootings (tolerating mass shootings? Do I really have to say those words?)
sends the message that we don't value human life here, life is cheap,
you and I are expendable, and it's much more important to keep guns in the hands of
anybody who wants them, including madmen.
Besides, mass shootings aren't that rare.
A mass shooting, defined as (not necessarily lethal) shooting of 4 or more people
in one incident, occurs nearly
every day in the United States.
Other countries are aghast.
The rest of the civilized world just doesn't operate this way.
American folklore says that our government might turn evil and take our guns, and the only
way to prevent this is to arm the populace heavily.
Do we have to make it quite so easy for totally untrustworthy people to get so many guns?
There are enemies besides this imaginary evil U.S. government!
I'm talking about our culture, not just our laws.
Mass shooters commonly violate existing gun laws.
I understand that responsible gun owners can make us all safer.
My idea of what constitutes "responsible" would set a rather high standard
(training, refresher courses, etc.).
But our culture right now is far too sympathetic to people who
are enamored of guns for the wrong reasons.
In fact, our gun culture may play into the hands of international terrorism.
In case you haven't noticed, Al-Qaeda and ISIL are at war with us.
How easy would it be for an enemy power to manipulate a mentally unstable American into
carrying out a terrorist act on their behalf, without ever having any direct contact with them?
It is not clear that this has happened yet, but I can assure you that groups like Al-Qaeda would
be glad to make it happen. They communicate with would-be recruits through the Internet and through
the magazines that they publish. They are glad when someone acts violently on their behalf without
having any contact that would leave a trail back to them.
And there are plenty of people out there who want to fight, but are easy to confuse about
who they're fighting for.
Afterthought: One right-wing position, which I have actually
heard expressed, is that the high frequency of mass shootings in
the United States is a good thing because it shows that we are safeguarding people's right to
defend themselves. I am extremely uneasy with this line of argument.
Uneasy to the point of nausea.
Latest reports are that the victims of the Umpqua Community College mass shooting
were singled out because they were Christians.
If so, they were martyrs. Lux aeterna luceat eis.
I am tired of having to mourn massacres regularly in the Daily Notebook.
I am tired of living in a country where anger, hatred, and violence are too easily
passed off as patriotism and virtue.
I am tired of living in a country where too many people love and idolize guns for
the wrong reasons.
I don't object to responsible gun ownership, but too many people have started saying they
"don't feel comfortable" unless they are constantly equipped to kill
others on the spot.
If you don't see anything wrong with that, you are playing dumb.
That is the only way I can describe it —
some of the loudest defenders of guns are pretending to be less intelligent than they are,
pretending not to understand things that any 10-year-old with a normal brain can easily see,
delivering their "cold dead hands" speech with their fingers in their ears and their brains
turned off.
And above all, I don't consider frequent massacres to be an acceptable price
to pay for the abundance of guns and people who misuse them.
This has to change. And I don't mean just laws; I mean the culture that glorifies
the ability to kill one's fellow human beings, and so easily turns angry people into mass
murderers.
[Revised.] Note that I am not against guns altogether. I understand that "good guys with guns"
can protect us. But I have a rather high standard of what constitutes a "good guy." For example, I approve
wholeheartely of a police officer who recently remarked that he carries a gun almost everywhere he can because
he doesn't want to deprive the public of his protection just because he's off duty. He'd feel terrible if
he saw something happen, knew exactly what to do, and couldn't do it because he didn't have his gun.
But an off-duty police officer is not just some guy with a gun. He has training, experience, and
accountability. He is certainly not a random person who loves guns and fantasizes about using them.
Personally, I wish all gun owners were required to undergo extensive training, with
periodic refreshers and some monitoring to make sure nothing happens to make them untrustworthy.
iPhone won't play music via Bluetooth through Ford Sync
(Bluetooth connection and cell phone audio still work)
One of the reasons I have the Daily Notebook is to archive things
like this for other people to find using search engines.
So here's today's technical note...
Symptom: Smartphone (in my case an iPhone 5) will not play music or
audio programs through the car's audio system using a Bluetooth connection
and Ford Sync. Cell phone audio still comes through the car's speakers and
microphone.
Solutions:
(1) Press Aux, Menu, turn the knob to Select Source, and make sure Bluetooth Audio
Stream is selected. But you probably already did this.
What happened to me this evening (after an iOS upgrade) is that Sync would say
"No Bluetooth device" in that situation, even though it was definitely connected
to my iPhone for phone-call purposes.
(2) Remove power from Sync by removing the Sync fuse (#3 in the 2012 Ford Escape)
or by disconnecting the car battery, preferably the former.
Leave Sync unpowered, with the car off, for 2 minutes.
Then reinstall the fuse, start the engine (needed to really get Sync going again),
and give Sync 2 minutes to reboot. You'll find that everything works again.
What did not work: Un-pairing and re-pairing the phone with Sync;
doing a master reset of Sync through its menu system.
Others have reported the same problem and cure, generally after an OS update on
their iOS or Android smartphone.
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