When it comes to putting a transmitter together for the BK, there are a lot of choices! My advice for a first-build '29 rig would be either a simple TNT or a Hartley-style oscillator. Both are easy to get operating and, when correctly optimized, are capable of putting out a nice-sounding signal.
For a first-time build, with the main objective being to have something ready in time for the December BK, I would not be concerned about overall appearance or period-appropriate parts. For now, the only thing that must be period-appropriate is the tube...improvements can come later.
As well, I would not be overly-concerned about running the maximum power of 10W input. If you are able to get a type '10' or the equivalent VT-25, or a pair of 45's, then the legal-limit is easily within reach. Utilizing something smaller, at just a few watts output, should not be considered a deterrent, as BK-operators all seem to have very good ears. Just 2 or 3 watts will guarantee plenty of contacts no matter where you are located!
Shown above is a fine little TNT built by Kevin, WB2QMY, in New York. It uses a very affordable UX-201A triode, originally manufactured in 1925 for radio receivers. Although Kevin's TNT puts out barely 2 watts on 80m CW, we had no trouble working each other in a recent BK QSO Party. If you build it, they will come!
If you prefer to tackle a TNT, here is the information you will need. This circuit appeared for several years in the ARRL Handbook's transmitter-section. I suspect that it was probably built by thousands of young hams in the late 20's and early 30's and affordably introduced most of them to the magic of radio. For more building details, including how to keep high-voltage off of the main tank coil, see the information on my website describing the TNT project.
Should you be interested in tackling a Hartley, here is an interesting circuit described by Nick, WA5BDU.
Such a transmitter would readily lend itself to a parallel arrangement of two or more triodes, such as the 27 or the 45 and would develop good power levels inexpensively.
ABØCW has designed a Hartley oscillator using a pair of 27's in parallel and uses them to drive a small amplifier. As described on his website, the oscillator would make a fine stand-alone transmitter with a simple link-coupling antenna circuit.
You can find a list of '29-style related building links, as well as a gallery of transmitters constructed by others, at the bottom of my TNT web page here.
And....circuit ideas, help with parts and lots of BK-chat can always be found at the Yahoo AWAGroup where the focus is mainly on building and operating.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].
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Bill Pasternak, WA6ITF, is the co-founder and producer of Amateur Radio Newsline. Contact him at [email protected].
See http://www.genesisradio.com.au/Q5/ . The website gives detailed schematics so you could always "roll your own".
Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.
The interwebs are abuzz with reports that the latest Windows update is killing counterfeit FTDI chips. Future Technology Devices International (FTDI) — according to Wikipedia — “develops, manufactures, and supports devices and their related software drivers for converting RS-232 or TTL serial transmissions to USB signals, in order to allow support for legacy devices with modern computers.”
The latest Windows update includes a new driver that is apparently “bricking” the knock-off FTDI FT232 chips by programming the USB PID to zero. This causes the device containing the chip to become inaccessible on any operating system. After the PID reset, apparently the programming cable itself will be rendered inoperable even on a non-Windows computer running Mac OS or Linux.
What might you have around the shack that could contain a counterfeit FTDI chip? Well, lots of things including that cheap USB radio programming cable you picked up on eBay. It’s not yet clear whether the affected FTDI chips are in any widely distributed radio programming cables.
While many radio programming cables advertise that they contain genuine FTDI chips, a post earlier this year on Hackaday shows that it’s not always easy to tell a fake from the real thing. One difference, apparently, is that the markings are laser etched on the genuine chip are often just printed onto the fakes.
If you experience a “bricked” cable due to this update, please report your experience in the comments including any details about the cable you were using.
Matt, W1MST, is the editor of AmateurRadio.com.
I have loads of fun in both the 160 tests and usually do quite well running 5 watts QRP. Each year I have done the tests I usually end up with a Certificate, but heck, if no one else enters and sends in their scores I guess that makes it easy to place huh?????I run a sideways “L” antenna , not the typical inverted “L”.
I run out about 125′ to a pole in the backyard, then take the other 60′ and run it to a right angle and down to about 5′ from the ground, the end at the house is on a 15’pole that is grounded, I use a balun at the feed and coil the coax as well into about 10 1′ turns. This antenna tunes very fast on 160 and its actual match at the shack is about 3:1 at the low end of the band. I have a 6′ ground rod at the base and no radials.
What I do find on 160 is that stations have no problem hearing me, however for me if I work the test both nights because of ground-wave propagation the stations I worked the night before are the same stations I hear the next night, my best chance to work stations out of my ground-wave is usually at sunset and sunrise.
This year I will give the KX3 a workout at 5 watts in the test.
Fred Lesnick, VE3FAL, is a special contributor to AmateurRadio.com and writes from Ontario, Canada. Contact him at [email protected].