(Brad) hath wroth:

I wish to make a 25 watt (short duty) 50 ohm dummy load for UHF 440Mhz
band. I have a UHF SWR meter and I have made dummy loads before, but they are
of little use at UHF frequencies due to internal capacitances in the
resistors.

Nope, not cazapitance. It's the lead inductance that usually causes
problems at high frequencies. That's why you normally see dummy loads
consisting of parallel combinations of resistors, not series. Look at
the photos in the ARRL publications (I'm too lazy to reach over to the
shelf and find the book and page number). The common method is to
take an SO-239 (yech) or a panel mount N connector receptacle, and
attach 4ea 220 ohm resistors from the center pin to each corner.

The only good dummy load I made that works very well at UHF is a
2 W 50 ohm straight carbon resistor solder on the inside of a PL259 connector.
I can use this as a 10W (short duty) dummy load as long as I make a brief
transmission.

A 2 watt carbon composition will sorta fit into a PL-259. No easy way
to add additional heat sinking, so that's about all it will do.
However, if you're sneaky, install the same 2 watt resistor, or the
coax connector previous described, on the end of a coax pigtail. Then,
shove the pigtail into any type of heat dissipating oil in a metal
can. Suspend the load so that it doesn't touch the sides. Think if it
as an updated Heathkit Cantenna. Choice of oil is a bit problematic.
Real xformer oil stinks. PCB's are still out there so be careful.
I've used peanut oil, canola oil, olive oil, engine oil, and hydraulic
fluid. Basically, avoid anything that turns rancid, is caustic,
smells bad, or conducts electricity.

A small 2 watt carbon composition resistor cannot move enough heat to
the case fast enought to handle much power. If you submerge such a
resitor in a very large bucket of oil, it will still blow up. My
guess is about 15 watts continuous duty and no more.

I thought about putting five 2 watt 10 ohm straight carbon resistors in
series inside a copper tube which is soldered to the back of a PL259
connector. What are your thoughts about this idea?

Not series. Think parallel. Take an RG-8/u or better yet, LMR-400
pigtail with a connector on only one end. The other end gets as many
resistors as you can ring around the coax end, connected in parallel,
between the center pin and the exposed shield. I figure you can get
about 9ea 470 ohm 2watt resistors around the cable.

Before you type your password, credit card number, etc.,
be sure there is no active key logger (spyware) in your PC.

I just use a camcorder, or digital camera in video mode, to record
someone typing in their password. I can then play it back and recover
the keystrokes. Beware of friends bearing cameras.

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