Ed,
No personal experience, but here are a pair of current sources.
Both Cubex and Gem quad have been in business for decades, but both are
under new ownership in the past few years.
Cubex is now in Michigan bought by the same guy who bought the Tennadyne
log periodic line
http://cubex.com/.
The Gem quad line from Canada had gone QRT for a while but seems to be
back in operation:
http://www.ve5si.sasktelwebsite.net/
There may be others, but these 2 spring to mind.
73 and good luck, Steve KW3A