On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann
wrote:

This looks very interesting:
http://www.qrpproject.de/UK/dipit.htm
No clue how to purchase one and it's only 1 to 42 MHz.

May 2003 QST article on building a "modern" GDO:
http://www.qsl.net/k8mcr/downloads/Modern_GDO.pdf

Feb 2013 Circuit Cellar article on building a GDO:
http://circuitcellar.com/wp-content/uploads/2013/01/CC25_ProjCard_Pres_Ball-CC271.pdf

Goes to 1GHz by changing both the oscillator and the coil with
frequency range. See "Plug in Oscillators" section:
http://elm-chan.org/works/ddm/report_e.html

July 2014 QST. Using an MFJ-259/269 as a GDO:
http://www.ka6wke.net/finished-projects/grid-dip-meter-coils
MFJ sells these as MFJ-66C:
http://www.mfjenterprises.com/Product.php?productid=MFJ-66C

Mo
http://w5dor.com/W5DOR-GridDip.html

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558