"What's in those attenutators, exactly, besides a potentiometer? "
Mine is soldered shut all around the box, so I have not looked inside... but here is how it acts:
At "min", input to gnd =200 ohms, input to output= 2 ohms, output to ground=200 ohms.
"centered", input to gnd =180 ohms, input to output= 220 ohms, output to ground=380 ohms.
At "max", input to gnd =48ohms, input to output= 510 ohms, output to ground=560ohms.
Any guesses as to whats inside? perhaps 2 pots and a couple of resistors?
A nice switched rf attenuator can be constructed using this guide:
http://www.merseyworld.com/wadarc/Te...Attenuator.htm
The values given are for a 50 ohm environment... for 75 ohm, recalculate the resistor values... 3db r1&r2=440 ohm r3=27 ohm; 6db r1&r2=220 ohm r3=56ohm; 10db r1&r2=140 ohm r3=106ohm; 20db r1&r2=91ohm r3=370ohm.
jr