You flip the transmit switch, your fingers tremble slightly as they adjust to the firmness of the cold straight key. A voice inside mumbles "a couple hundred milliwatts?..yea I dunno," with guarded hope you begin to tap out CQ. Soon you send on autopilot and your mind wanders to some distant place you only hope the little signal might reach. Then, with senses peaked, a flip of the switch and the receiver snaps to life. Two seconds of noise then, is it?..come on...calling me?..yes..confirmation! Your call has been heard and the QSO is underway! You've just experienced what seemed impossible, the magic and awe of the Tuna Tin 2!
You've heard of QRP right? Five watts of power on CW or ten watts PEP on SSB. Well, how about QRPp? The little extra "p" tacked on to the end means you're "Milliwatting" man! We're talking power in the area of a half-watt or less! Enter the mighty Tuna Tin 2 QRPp transmitter!
The late Doug DeMaw - W1FB, designed this classic QRPp transmitter. Of the many homebrew projects designed by Doug, the Tuna Tin 2 is undoubtedly his most famous. The little fella pictured above produces 250 Milliwatts of mighty QRPp power on the 40-meter band!Preview the Tuna Tin 2 Schematic...
The keying of my Tuna Tin 2 is chirp free. I added an extra 2N3906 as a keying transistor, found hiding under the circuit board along with a couple of associated resistors and a cap, as it helped improve keying performance. The extra transistor also makes the rig ultra safe to use with my surface mount Tick 3 microprocessor electronic keyer. I also added, at the suggestion of the ARRL's QRP and Tuna Tin 2 fanatic Ed Hare - W1RFI, a simple band pass filter that insures compliance with today's spectral purity regulations.
I found that the TT 2 operates great using either the old FT 243 or the newer HC 18 crystals. The newer ones are those that come in a small metal can and feature wire leads. But I thought mine looked "way cooler" outfitted with an FT 243 socket with the old style crystal magnificently displayed right on top of the PCB! And why not? I was lucky enough to find a bunch of the old style rocks in the junk box. Lucky is right! Those old style FT 243 crystals, at least ones cut on decent frequencies, are now nearly impossible to obtain. (Like any good ham I kept all those old crystals from my novice and early days as a general.) But hey, like I said, the newer crystals work great too.And the Tuna Tin Rocks!
Does it really work, just 250 milliwatts? Yup, it sure does! My best DX to date was a QSO with F6IPA in Moirax, France, made November 3, 2001 at 07:10 UTC. I had an old 7.015 MHZ rock plugged in and he was workin' a contest right on frequency! I fired off my call and he came back with a 559 report! With 250 Milliwatts power, that's a whopping 26,000 kilometers per watt! And hey, we're not talking enhanced F2 skip on 10 meters at the peak of the sunspot cycle. This is 40 meters here! I gotta admit though, the antenna is a pretty decent 40-meter radiator, being a 200-foot long, off-center-fed Windom, connected to the shack with 450-ohm low loss ladder line. So far I've completed 172 QSOs with this little rig, which includes 38 states and 4 DXCC entities. Hey, that's not bad for a little rig sporting barely enough power to light a dim flashlight!K0KP's Tuna Tin 2 Log : WAS QRPp Contacts
So, what are you waiting for? Now! So you don't forget, build yourself a Tuna Tin 2 and get in on the action! I'll be lookin' for your Tuna Tin 2 on 7.040 MHZ!Download plans to build yours from this link to the ARRL website (PDF Document)
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