Hi everyone,
I'm trying to build a dummy load using one of those 50 ohms/150 watts used flange mount termination resistors you'll get on the internet. The plan is to mount this resistor (G150N50W4B) on a CPU cooler (w/fan) capable to dispose some 100 watts. The resistor will sit in a small metal enclosure along with a BNC connector.
Now I thought it would be very handy to have an additional output that is 30 dB below the input for monitoring / measurement purposes. I've calculated a PI attenuator and selected resistors from the E96 series. Since I can't use 52 ohms shut resistors, I'll have to be happy with a VSWR of 1.06. I'd like to use the dummy load up to 450 MHz, maybe 1.2 GHz if possible.
tldr; -> and here's the challenge:
Is it possible to build a 30 dB attenuator with only one PI network?
Usually I'd split this into 3 x 10 dB to minimize the stray capacities and crosstalk over the series resistors. Unfortunately I can't build a 10 dB attenuator with a 50 ohms input shunt unless I'd tolerate a VSWR of 1.6.
So how could a 30 dB att mechanically being built? Maybe it would help to to split the series resistor to 3 x 250 ohms and intruduce shielding chambers for each resistor?
Any other ideas would greatly be appreciated...