Two sources for HF to VHF upconverters for SDR experiments.
At Reddit /r/RTLSDR
http://www.reddit.com/r/RTLSDR/comments/12ebes/informal_upconverter_comparison_janielectronics/
Remote SDR using Raspberry Pi & RTL_TCP
AR.Drone RC mod
Extends flight range to 1.5 – 2.5 kilometers
By Albert at Dronehacks
http://dronehacks.com/2011/08/21/ar-drone-rc-mod-extends-flight-range-to-1-5-2-5-kilometers/
Python and GPS Tracking Tutorial
Bricktronics
Lego meets Arduino
Arduino motor shield
1 MHz crystal oscillator
A low powered radio transmitter.
Jameco part number: 27861
Linking an Arduino to a Radiometrix NTX2 Transmitter
http://ukhas.org.uk/guides:linkingarduinotontx2#where_to_buy_the_ntx2
For high altitude telemetry using RTTY.
Raspberry Pi Sends Live Images from Near Space
The crystal set of AM transmitters
audio transformer + crystal oscillator + battery = AM radio
At scitoys.com
http://scitoys.com/scitoys/scitoys/radio/am_transmitter.html
source of radio parts for this type of project:
http://www.scitoyscatalog.com/category/R.html
Radio Shack has audio transformers…
http://www.radioshack.com/product/index.jsp?productId=2103254