"Easy Ten" - A simple 80 Meter CW Transmitter Using A 2N3904 by K7NS
I call this very simple transmitter the "Easy Ten" because it can be easily heard at a distance of 10 miles. Transmitter antenna is a random length wire run through a hole in the wall and thrown into a tree.
http://www.sparkbangbuzz.com/easy-ten/easy-ten.htm

3.5MHz ARDF Transmitter by ON7YD
This transmitter is designed as a classic 3 stage TX.
http://www.qsl.net/on7yd/atx80.htm
 

3.5MHz Low PowercARDF Transmitter by ON7YD
This low power transmitter is developed for ARDF exercising purposes but of course can be used as super QRP transmitter either.
http://www.qsl.net/on7yd/minitx80.htm

80 Meter Tube Transmitter by SM5GNN
This is a variation of the triode/pentode family of glowbug transmitters. It features a Pierce oscillator which runs continously during transmit to avoid chirp.
http://www.tuberadio.com/80.html

80 Metre DSB Transmitter by VK3YE
This circuit is probably the simplest practical 'bare-bones' voice transmitter for the 3.5 MHz amateur band.
http://home.alphalink.com.au/~parkerp/projects/proj80ds.htm
 

80m 0.5w Mini Transmitter by G3ZOI
This 80m ARDF transmitter was designed to be multi purpose, suitable for Classic, Sprint and FoxOring formats. Compact and lightweight and easy to deploy. Low component count. Multipurpose socket for charging/syncro/tune-up. Internal ATU for matching to a short wire antenna.
http://open-circuit.co.uk/wp/transmitters/mtx80/

80m 3W Transmitter ATX-80 by G3ZOI
The 80m TX described here is the well known ON7YD ATX-80 and timer, combined in a standard aluminium enclosure.
http://open-circuit.co.uk/wp/transmitters/mtx80/

80-meter CW Transmitter by K9PPW
This is a schematic of Bob's homebrew QRP transmitter. It's CW on 80 meters, about 1 watt output, VFO ... and only uses TWO rf transistors and one more for keying. It was built as an experiment to see what you could get out of ONE transistor (about 250 mw with no chirp) and the "shoes" were added later to get a whopping one watt of rf out.
http://my.core.com/~jematz/qrp/k9ppw-s1.htm

Fox transmitter for 80m by PA3HCM
One of the members at the club pointed me at the so-called “OXO transmitter”. I looked it up at the internet, and immediately liked its simplicity. So I started to build it.
http://www.pa3hcm.nl/?p=294#more-294

Frequency agile 80 metre CW QRP transmitter by VK3YE
http://home.alphalink.com.au/~parkerp/projects/pro80cw.htm
 
 

Fuchsjagdsender - Der kleine Fox durch DL1DMW
Wer schon einmal an einer Fuchsjagd teilgenommen hat, weiß, wie viel Spaß sie bereiten kann. Für die Fuchsjagden des Ortsvereins Soest, wurde dieser wenig aufwendige 80-m-Fuchs aus zwei vorhandenen Lösungen kombiniert.
http://www.amateurfunkbasteln.de/fox/fox.html

OARC-80 by WAØITP
This is a fun little QRP transmitter that was developed for a club project. I had wanted to try an oscillator on a chip, but had heard the Epson chips had phase shift problems.
http://www.wa0itp.com/oarc80.html

Simple 80m TX by EI9GQ
This simple circuit will give about 1.2 Watts of output when powered from a 13.8VDC supply. If you don't have a 2SC1237, try any other 12V CB radio output transistor 2SC1969, 2SC1307 etc.
http://homepage.eircom.net/~ei9gq/tx.html

TAG 80 Transmitter by G4RAW
Original Circuit in SPRAT Summer 1994 Iss Nr 79
The original version was built on tag strip, hence the name.
http://www.qsl.net/g3pto/g4raw.html

Ten Minute Transmitter by G4RAW
Steve, G4RAW described this simple transmitter for 80 metres in Sprat 82 and describes how the World record for building a rig , actually a Oner, and having a QSO, is under 15 minutes.
http://www.zerobeat.net/g3ycc/tenmin.htm

The Nipper 3.5MHz Transmitter
I think that this circuit was developed by G3ROO but my notes are lacking in this information.
http://www.qsl.net/g3pto/nipper.html
 

Your first transmitter by PA3HCM
With just a few components, you can make your own morse code transmitter. The output is only a few miliwatts, but this is enough to receive on any radio in your home.
http://www.pa3hcm.nl/?m=200208