Sunday, September 18, 2011

40m EFHW for the Tiny Tornado

Keeping with the theme of ultra compact, I made a 40m end fed halfwave coupler based on the suggestion from http://www.nfarl.org/mart/node/34

Forgive the blurriness of the picture, but it's basically just an 11uH inductor in an L network w/ a 50pF trimmer. RCA plug on the left, euro binding post on the right.

Here it is all cased up in a short piece of 1/2 cpvc. Adjustment hole on top, and binding screw to connect the 1/2 wave wire is on the left.
It's raining today, so I haven't had a chance to take it out and throw up a wire to test it, but on my ft817 it indicates no SWR... So it's a start.

73 and good QRPing
Jim - AB9LM


Tuesday, September 13, 2011

40m Tiny Tornado w/ PTO

I recently completed building a 40m Tiny Tornado with PTO VFO from scrounged parts.

Tiny Tornado details can be found at:
http://www.indianapolis.net/QRPp-I/KA8MAV_VFO-TT-40.html

I wanted a small cw transceiver that was easy to build, super cheap, and that would fit inside my favorite project enclosure.




Although I wanted to fit the 9v battery inside, I felt that it was a waste of precious altoids real estate.
Instead, I soldered some 9v snaps to a piece of PCB and attached it to the side. Doing this, I'm left w/ some extra room to put a key, or maybe an earbud.





The circuitry turned out a bit messier than I would have liked... I'm certainly no master at Manhattan style building. Not to mention, after soldering the board into the tin, I realized I still needed to drill some holes in the chasis. Booo!

Anyway.. The important part is that it works, and works well as far as I'm concerned. I'm able to tune the entire 40m band... From the CW side, all the way to the end of the phone portion. After a couple minutes of warmup, the VFO is quite stable. With a tuned antenna connected, I'm able to copy even weak signals with little trouble. Although this is a direct conversion receiver, and would need a RIT ordinarily, I think that keying down pulls the VFO just enough to give me the proper amount of shift. .. Which is a good thing, because I dunno how to put a RIT into this PTO VFO.

Into a dummy load, I measured about 300mw on a 9v. I've not had a QSO yet, but very close. I heard a station calling CQ, so I replied... He came back with AB9DM? My attempt to correct him failed as my paddle hose up.

I plan to post a video showing the audio, but as of this writing, I have S9 QRN at my location.
I'll also be putting up a pic of the compact EFHW tuner that I'm working on exclusively for this rig.

73 and good QRPing
Jim - AB9LM