Monday, May 23, 2011

D-Cell DX

In two week's time Victoria and I hope to begin our walk across Austria along a new footpath, Der Donausteig. The trail follows the river Danube from the village of Grein, to the confluence of the Inn, the Ilz and the Danube, at Passau, Germany; a hiking distance of some 280km (170 miles).

From Passau we'll travel by train to Friedrichshafen, where we're meeting friends at Europe's equally famed confluence of radio amateurs. Following the hamfest we'll spend a week with Vic's family near Lago Maggiore in Italy.

I'll be carrying a "minimalist" 20m CW homebrew QRPp transceiver in my backpack. This radio was designed to be powered by a candle-heated thermoelectric generator (TEG). I call this radio, "Candela." Although I had my heart set on working "DX by Candlelight," alas, it appears as though I won't finish the TEG before we depart. "Plan B" is to operate this radio using a single D-cell flashlight battery. My antenna will consist of an end-fed, half-wave wire held aloft by a convenient tree branch.

The transceiver circuitry is mostly old-hat. For example, the exciter consists of a VXO'd 14.058MHz quartz crystal covering ~14.040 to 14.059MHz. The push-pull final amplifier was "cook booked" from a low supply-voltage design by DL4ALJ and DL2AVH. I also drew inspiration for my transmitter from Pekka, OH1WX's, low-voltage, 80m transceiver, which may be seen here.

The receiver amounts to a single-balanced diode mixer followed by a single-stage transistor AF amplifier. This transistor drives a pair of ultra-cheap piezoelectric earphones. 

The entire setup, minus the antenna and battery, is shown in this photograph (please "click-on" the pix to enlarge). My friends will be surprised to see my new Palm PPK, hand key. That's right guys, I've actually bought something that wasn't made before 1964!

The transceiver dimensions are 130 x 66 x 40mm. It weighs in at 227grams. The tuner, phones and key add 255grams, and the D-cell battery another 150grams to the carrying weight. 

The tuning dial is an aluminum disk with a paper scale over which I applied a clear "contact" plastic film. The "antique" finish was obtained by over-spraying the adhesive on the back of the dial paper (I'm not good with glue). 

The odd-shaped plastic box shown in the upper right corner is the tuner for an end-fed half-wave (EFHW) wire. It's simply a tapped-LC resonator. A high Qu ferrite core taken from my junk box was wound with 17 turns, producing an inductance of 3.6uH. The variable capacitor used is a lovely, miniature air-trimmer made by Johnson; a fine old name in American electronic components.

The inductor is tapped at both the 2nd and 3rd turns above ground. These tapping points are brought out to individual BNC connectors. The lower tap matches 50 Ohms to 4640 Ohms. The higher tap matches 50 Ohms to 2106 Ohms. The EFHW wire attaches to one of the bolts protruding from the top of the plastic case. A counterpoise wire attaches to the other bolt.

The tiny meter located at the upper right-hand corner of the transceiver is the null indicator for a resistive impedance bridge. The toggle switch below the meter is used to either insert or bypass the bridge between the transmitter output and the BNC antenna connector (located on the left box end). R/T switching is accomplished using the DPDT toggle located in the lower right-hand corner (R/T antenna switching and receiver muting).

Sidetone monitoring is provided by a vintage GE, 2N2646 unijunction.

A photo of the transceiver circuitry is shown below. The board located at the bottom is a triple-resonator bandpass filter having a rather tight-bandpass. This was necessary due to a 100kW SW station located in Nashville, Tennessee which throws a beam directly at New England on 13.845MHz (I also copy their bible sermons on the gold crown located on my upper molar). 

With an input supply of 1.0Vdc the transmitter RF output power is 28mW. At 1.2Vdc the output power rises to 50mW, and at 1.5Vdc the output is 84mW.  Although the transmitter will produce a stable RF output of ~10mW with a supply voltage just over 800mVdc, the receiver does not operate below 1.2Vdc.

Here's a shot of the transmitter output spectrum. The second harmonic is the worst offender at -51dBc.

I've been making QSOs with this radio for the past five or six weeks. Most of these contacts were made with the radio assembled on my usual "lazy man's" plastic proto-board. All of the contacts were made using a 1.4Vdc supply. The RF output power varied from 90mW to 72mW. Here's a list of the DX worked so far.

YV5DTJ     599/559     Venezuela     3919km
DL3JFA      589/559     Germany     6102
DL4KCA     599/559     Germany     5726
DM8YL       599/"599"   Germany     5932
E79D         599/"599"   Bosnia         6877
VP9KF       579/"599"  Bermuda      1479
IK2SND      589/449     Italy            6185
F5NBX       599/?         France         5636
I5TYQ        599/539     Italy            6421
LZ1JRF      599/"599"   Bulgaria         ?
P43E         599/"599"   Aruba           3519
YU7KM       599/429     Serbia         6942
V44KA       599/449    St. Kitts        3124
OM2011IIF  599/"599"  Slovak Rep.  6532

I look forward to working you from the banks of the Danube, the shores of the Bodensee and Lago Maggiore come next month, so please keep an ear cocked for my little "D-cell DX" machine!

One more thing...the contact with DL4KCA turned into the "April Pix of the Month" at the G20 Section of the DARC. My thanks to Joe, DL4KCA and Graeme, DO1KGW

Mike, AA1TJ

Sunday, May 15, 2011

May 16, 1981

It was as the photograph would have you think. She was beautiful, and her heart even moreso. Not only that, she had been my best friend since we literally were children.

As the years flew by I began to notice that love is not simply a case of admiration taken to an extreme. To love someone with all of your Being is also to make yourself worthy of their love. It's a struggle that for me continues to this day. 

The saving grace is that over time we come to resemble what we most love. I thank my lucky stars that she is by now in the marrow of my bones. Come what may, it will remain so until the end of my days.

So far as I'm concerned I hold the winning ticket to the only lottery that matters in life.

Happy 30th, Victoria.

Ti Amo,

Tuesday, May 3, 2011

Death Euphoria

By 1865 the American South hated Abraham Lincoln no less than Americans hated the late, Osama Bin Laden. Several hundred thousands of their sons had perished, their farms had been plundered and their cities razed. They had been starved, humiliated and all but beaten. Lincoln wore the face of their oppressor.

Many Southerners rejoiced when word of President Lincoln's assassination reached them. One of the revelers, John S. Wise, later wrote, "...among the thoughtless, the desperate, and the ignorant, it was hailed as a sort of retributive justice. In maturer years I have been ashamed of what I felt and said of that awful calamity." Beware of People Weeping; Public Opinion and the Assassination of Abraham Lincoln, Thomas Reed Turner, p.97

If a madman were to burn down an orphanage, what sort of person would howl with delight at finding the madman's corpse amid the piles of small, charred bodies? Bin Laden murdered three thousand. Manipulation of the fear and hatred for his misdeed was used to kill upwards of a hundred thousand; and counting. Bin Laden may have struck the match, but a legion of madmen of every stripe rushed in to light their torches from it. Placed head to toe, the resulting line of corpses would extend for one-hundred miles. What possible cheer could come from lengthening that line by six feet - even by six notorious feet - now that the orphanage has been burned to the ground? 

"For Christmas that year, Julian gave Sissy a miniature Tyrolean village. The craftsmanship was remarkable. There was a tiny cathedral whose stained-glass windows made fruit salad of sunlight. There was a plaza and ein Biergarten. The Biergarten got quite noisy on Saturday nights. There was a bakery that smelled always of hot bread and strudel. There was a town hall and a police station, with cutaway sections that revealed standard amounts of red tape and corruption. There were little Tyroleans in leather britches, intricately stitched, and beneath the britches, genitalia of equally fine workmanship. There were ski shops and many other interesting things, including an orphanage. The orphanage was designed to catch fire and burn down every Christmas Eve. Orphans would dash into the snow with their nightgowns blazing. Terrible. Around the second week of January, a fire inspector would come and poke through the ruins, muttering, "If they had only listened to me, those children would be alive today."  Tom Robbins, Even Cowgirls Get the Blues

If it were possible to kill our way to Utopia we should have arrived long ago.