[Amps] Caddock power resistors

[Rod Elliott]

At 19:14 11/13/2007, you wrote:
>[snip]
>I used some Caddock power resistors in the grid circuit of the
>"Sunnyvale/Saint Petersburg Kilowatt Plus" that appears in the 1999-
>2004 ARRL handbooks.  They are mounted on a pretty big heat sink, and
>have their own fan.  This setup has been very satisfactory, and
>capacitance hasn't been a problem.

I did a ballpark calculation of the capacitance of one Caddock MP9100 
unit, and came up with 5pf. Using that value with their specified 
inductance of 20nH gives a self-resonant frequency in the order of 500 MHz.

Wiring four of these units in series/parallel would produce a 400 
watt power rating. If mounted taking great care to minimize lead 
lengths, the self resonant frequency of that array would not be much 
lower than that of a single unit. Should be able to use these at HF 
without compensation.

Interesting!  Anybody know what these units cost? ... couldn't find 
them in my DigiKey catalog

Cheers
Rod VE3UW