Thursday, November 24, 2011

An Early Winter Thanksgiving

Victoria and I had a tranquil and happy Thanksgiving. We began the day with a long walk through a winter landscape; courtesy of yesterday's 25cm snowfall. As usual, much of our organically grown Thanksgiving dinner came from our garden. The items that we grew ourselves are italicized below.   

  • Acorn squash stuffed with brown/wild rice, French lentils, mushrooms, onions, cranberries, bread crumbs and sage
  • Green beans with tahini sauce
  • Cranberry-apple relish
  • Roasted red and yellow beets, carrots and almond slivers
  • Pumpkin pie for desert (not shown)
For some, Thanksgiving wouldn't be the same without the turkey. As such, I'm including a photo of a wild turkey in flight. Victoria discovered a gathering of more than a dozen turkey just outside our front door some weeks ago. Of course when she stepped out with the camera they were airborne before she could depress the shutter.

A photo of this year's kitchen garden. 

We harvested ten pounds of shelled hazelnuts from our mini-orchard of nineteen trees in September. The hazelnuts shown in the left-hand basket are still in the cob. The ones on the right have been shucked but not yet shelled.

We picked 140 pounds of apples this year. Filling for one apple pie per month for the next year is in the freezer and we've a half-dozen large bags of dried apple rings in the pantry.

We made a total of three gallons of apple sauce. The rest of the apples are down in our root cellar, along with the potatoes, carrots and other miscellaneous root vegetables.

“If you look the right way, you can see that the whole world is a garden.”
 Frances Hodgson Burnett

Lavender 2011

Saturday, November 19, 2011

The Tao of QRPp

I sometimes imagine that milliwatting on the high-frequency bands must be a bit like sailing a dinghy across a busy ocean shipping lane. For long spells it's as though you are alone, bobbing upon a vast sea. Suddenly a huge ship appears from nowhere. Judging from it's course and speed there's little doubt that it hasn't seen you, and it likely never will. Your only option is to get out of the way. Only when it has passed can you return to your intended heading. It's not only the traffic, but weather as well that can upset your hopes for a successful voyage. 

If a man is crossing a river
And an empty boat collides with his own skiff,
Even though he be a bad-tempered man
He will not become very angry.
But if he sees a man in the boat,
He will shout at him to steer clear.
If the shout is not heard, he will shout again,
And yet again, and begin cursing.
And all because there is somebody in the boat.
Yet if the boat were empty.
He would not be shouting, and not be angry.

The challenge of milliwatting involves navigating through both QRN and QRM. The operator knows before he sets out what he's getting himself into. One moment you're sailing on an empty frequency and the next you find yourself 40dB beneath the hull of a leviathan.

Nature made QRN and QRM alike. And whether QRN or QRM, every difficulty that we face adds another line of bumpers to the pin-ball table. One of life's little joys is reflecting on where all the bumpers were when you did something worth remembering.       

Two winters back, while calling a DX station on 80m, another station turned up on frequency with the comment, "PISS WEAK" at the end of several of my transmissions. In a "just so" story the DX station would have picked up my call, allowing me to clench my jaw and send for all to hear, "RIG ONE TRANSISTOR ES 85MW." Of course the DX station didn't hear me that night. In retrospect I'm glad that he didn't. At least not then. 

     Who can free himself from achievement
     And from fame, descend and be lost
Amid the masses of men?
He will flow like Tao, unseen,
His steps leave no trace. He has no power.
He achieves nothing, has no reputation.
Since he judges no one
No one judges him.

Such is the perfect man:
His boat is empty.

Chuang Tzu

Friday, November 18, 2011

My First QRPp Contact

My "Elmer" KØYTI (now AAØA) handed me a stack of 73 Magazine back-issues back in 1971. I was fourteen years-old at the time and already becoming bored with my store-bought radio equipment. I responded to an advertisement in one of the 73 Magazine issues (shown below) by sending off an order for $3 worth of MPF102 JFETs. I chose the MPF102 because it was the least expensive device offered!

Having received my field-effect transistors I set about trying to build a crystal-controlled oscillator for the 40m band. I mounted the components on several bakelite tie-strips, which were themselves screwed down onto a wooden base.

After several days of trial and error I finally heard the oscillator's signal on my shortwave receiver. I used my only piece of test equipment - a VOM that I had purchased from a nearby Radio Shack outlet store - to measure the total DC input power to the oscillator. With a fresh pair of 9Vdc "transistor radio" batteries in series, I calcuated the input DC power was just over 50mW.    

Soon afterwards I had the idea of coupling this oscillator to my 40m dipole antenna. Having no idea how to calculate the optimum number of coupling turns at the tank inductor, I tested various windings by measuring the relative output at the antenna with my VOM, set to read "volts," in series with a germanium diode.

Having placed my straight-key in the circuit I began calling CQ. I didn't know if I could be heard outside my neighborhood, much less outside of my city. 

I was still at it some days later with not so much as a nibble. I must have sent out five-hundred calls to no avail when, at last, I heard a station returning my call sign. It was W3EGL/Ø in Rochester, Minnesota; a distance of 388miles or 624km. We easily exchanged reports. Obviously, I was ecstatic over the contact.

Alas, both his QSL card and my old log book are long gone, so I can not tell you what the signal reports were. However, I recall from his QSL that he'd been using a pair of military surplus "Command" radios..."BC" something or other. I remember thinking it was pretty neat that he'd heard my tiny signal on such old and basic equipment. 

I called for some time, off and on, in the following weeks, but this was to be my only QSO made with a handful of milliwatts in those days. What with school, dating and jobs, I eventually left amateur radio for what turned out to be a period of over twenty-five years.

I returned to the hobby in 2008 with the aim of making "homebrew milliwatting" my primary focus. In early 2010 I rebuilt the MPF102 one-stage transmitter from memory. Using the same drain supply voltage as before, I noticed the output power varied considerably from one MPF102 to another (the Idss and Vp values lie in a broad band of values from one device to the next), but it generally fell within the range of 10 to 20mW. 

However, by 2010 I had developed an interest in early semiconductors. Accordingly, I replaced the MPF102 with one of the earliest modern silicon JFET's.

The first commerical field effect transistor appeared in France in 1958. This was the Technitron; brainchild of Stanislaus Teszner. Unfortunately, this germanium alloy device suffered from very low gain and high reverse-leakage.

Crystalonics of Cambridge, Massachusetts produced the first commercially available silicon JFET in 1960. Although the reverse-leakage was vastly lower than in the Technitron, and the transconductance was an order of magnitude higher, it was a poor perfomer in comparison with modern silicon JFETs. In fact I have four of these devices in my collection. Only one of the four - type C632 - is barely capable of producing sustained oscillation at 4MHz. The listed transconductance for the three type C631 devices in my possession is only 125uMhos with a pinch-off of 30V and up to 50pF of interelectrode capacitance!

It was the advent of Jean Hoerni's planar technology in 1959 that paved the way for modern, high-performance silicon JFET's. The first of these to be produced was a line of P-channel devices made by Texas Instruments, beginning in 1962: the 2N2386, 2N2497, 2N2498, 2N2499 and 2N2500.

I replaced the MPF102 in the QRPp transmitter of my youth with a 2N2499. My sample bears a date-code of September 1962; a very early device indeed. Given the May 1966 Texas Instruments price guide lists the 2N2499 for $12.90 (equivalent to $86 in 2010), I shudder to think what it must have cost in 1962 (the first JFET project to appear in QST Magazine debuted in 1966).   

The RF power output was actually a bit higher using the 2N2499; at 28mW vs. 10 to 20mW with the MPF102s. I paired this transmitter with a regenerative receiver built from an early 2N2386 JFET (regenerative detector), direct-coupled at the source resistor to a 1957-vintage 2N107 PNP germanium transistor (AF amplifier stage).

On 6 May 2010, K1GOW in Providence, RI answered my CQ on 40m. Joe was running 3 watts to an end-fed wire only 15 feet off the ground. The distance between us was 167miles or 270km. The reports were 569/439. 

On the next day I worked KA2PQY in Milmay, NJ (338mi/544km) with 569/339 reports.

On 10 May I worked two stations: N2AYI in Carney's Point, NJ (332mi/535km) with 579/539 reports, and, KA2KGP in Forestville, NY (340mi/547km) with 569/339 reports. BTW, Tom's QRZ page notes that he is a deaf CW operator.  

Thursday, November 10, 2011

Something Crazy's Going On

I've been out of the saddle for some weeks now due to family issues. At last, this afternoon I lowered myself down into the Hobbit Hole with the aim to have some much-needed fun. Well, I did that plus some; only, I'm a little confused right now.

Once in my shack I quickly threw together a 40m, crystal-controlled, Pierce oscillator using a germanium grown-junction alloy transistor. This one was made by General Electric back in September of 1956; type 2N78. As the maximum data-book 3db-down cutoff frequency is only 6MHz, I'm pushing it a bit. With 12V on the collector the RF output power is 5.6mW. Not much, on the other hand the worst harmonic is -45dBc with just a simple LC tank in the extra LPF required.

1957 Radio Shack Catalog

Next I built a one-transistor regenerative receiver using the same type 2N78 transistor. It even has the same date-code. For simplicity I placed my 1950's Czech military surplus "4k Ohm" headphones directly in the collector return to the +6V supply line.

Likewise, I plumbed my Czech mil-surplus straight key to the transmitter. The antenna was my usual 135' end-fed wire erected at 35' on the ends.

The band was busy so I ended up calling CQ at 7041.6MHz; smack between some "letter" stations. I called for about an hour with no luck. Having only three 40m quartz crystals, I kept checking the lower two frequencies for a clear spot. Eventually there was a lull on 7014.7kHz so I began calling there. It didn't last long. In less than five minutes I found myself buried in a resurgence of DX activity. But now I noticed my third quartz crystal frequency was open so I QSY'd up to 7029.7kHz, where I took up calling CQ again.

At 2134z a strong station answered my call. It was K8CIT calling from Michigan (554m/891km). Art was 589 to 599 here with his 100w and 80m loop at 60'. He gave me a 429. We ended up having a great QSO lasting until 2150z. Art copied everything I sent: details about my rig, the transistor type, my receiver, etc..

When I came up to the house for dinner I decided to check the RBN to see if any of my calls had been captured. Indeed, I was logged a number of times by RBN receivers in NH and PA, with SNRs from 1 to 5dB. But right at the top of the list was a RBN capture at a SNR of 14dB. The RBN station that logged me was DL8LAS near Kiel (3599m/5792km)! Everything about the logging seems correct: frequency, sending speed, etc.. It appears that my antique transistor was heard in Germany this evening on 40m...all 5.6 milliwatts.

15 December 2011 Update: Peter, DL3PB, may have solved the mystery!  There appears to be a bug in the RBN software that occasionally prompts it to capture your call sign as sent by another station, and present it as though it had heard you calling CQ. This would make sense as the DL8LAS listing of my call is approximately the time that K8CIT would have been signing-off with me. It very well may have gotten my call sign from K8CIT. Thanks Peter!

K2LP answered my CQ on 15 November 2011. The reports were 599/559. Bud's strong signal blocked my little regenerative receiver so badly that I resorted to copying the "thumps" tone heard whatsoever! ;o)