Late breaking update 12/14/2014:
With the help of some folks on the SKCC sked page, the Mighty Mite completed not one, but two QSOs this evening! Both with stations in Tennessee, KC9W and KT4TN, both operators coincidently having the first name Randy. Thanks Randy’s! Reports were 229 and 449 respectively, and we made complete exchanges.
This is an update on the progress of the MMM.
Encouraged by successful oscillation, I have added the bits necessary to put the MMM on the air. These include
- A low pass filter on the output.
- A simple RX – TX switching arrangement
- A coaxial connector for power in, and an LED indicator showing when power is available to oscillator
- A 1/8 inch stereo jack for plugging in a key, and…
- little rubber feet.
Of all of these, I cannot sufficiently emphasize the importance of little rubber feet. A project just cannot be considered complete without them. The rig now looks like this:
Second only to rubber feet in importance is the low pass filter. The oscillator in the MMM is rich in harmonics that absolutely should not be put on the air, even at the very low power level of the mite. Fortunately, there are excellent Internet resources available for designing and building them. The best one I have found is A Short Guide to Harmonic Filters for QRP Transmitter Output.Revd. George Dobbs G3RJV
Not only does George explain how to design your own, he supplies calculators on the site, and even gives component values for common filters. I chose to build one of the pre-calculated filters, you can see it in the photo at the back of the board.
All tricked out, my MMM is delivering a solid, non-chirpy 300mw. Saturday there was a RTTY contest running full bore on 40 meters, so I didn’t have much luck being heard. This morning however, everything was nice and quiet, and I tried a few CQs. No answers, but I did turn up on RBN
Actually, not bad, it’s getting out there. I’ll keep trying on 7.050 and see if I can raise a QSO.
Now really, I have to get back to building my regen.