OK, what's a pulse transformer?
It that what I refer to as a balun? In either case, you still lose at least 50% of the signal to each leg.
And, I dispute that 6 db loss figure. Assuming 100% efficiency, each leg of the split will be down only three db (or half the original signal) , not six (which would be one quarter the original signal).
spin it as you will, each split results in at least a 3 decibel loss.
Quote:
Originally Posted by hermanv
Using a resistive splitter each leg will be down to 1/2 the voltage. Since impedance is constant at 75 Ohms each leg will also have 1/2 the current (E over R is 1/2 of what it used to be). So 1/2 the voltage times 1/2 the current equals 1/4th the power or 6 dB.
dB for voltage = 20 * (log of ratio) for power it's 10 * (log of ratio). For a resistive splitter the voltage ratio is 1/2 so the dB equation is equal to 20 times (log of ratio). So, log of 2 is 0.3010299 times 20 equals 6.02 dB. You get an identical answer if you use 1/2 for the ratio instead of 2 (log of 0.5 is -0.3010299 times 20 equals -6.02 dB. Using the power equation it's the log of 1/4th or .602. 0.602 times 10 gives again 6 dB, in other words both voltage and power equations result in the same answer (as they should).
Using a transformer the ratio of each secondary to maintain a 75 Ohm input Z will be 1.414 to 1. On a transformer the impedance is the square of the turns ratio times the secondary load or 1.414^2 times 75 equals 150 Ohms. With two secondaries in parallel the Z returns to 75 Ohms (1/2 of 150). This means the voltage at each secondary is .707 times the input voltage not .5 times the input voltage. In a resistive splitter power is dissipated in the resistors, in the transformer design no power is lost (except for that power that is lost to imperfections which luckily are small in comparison) that's why the transformer solution results in less lost power, none of the power is converted to heat in any resistors. It is not practical to make a wide band transformer at home.
"The loss in a good splitter is around 4.0 dB per split. An average splitter has around 4.5 dB loss per split. (A two way splitter has one split, a four-way has 2, an eight way has 3.) Thus an average eight-way splitter should have about 12 to 13.5 dB insertion loss."
http://www.hometech.com/video/splitters.html
Here's one that has less loss, but it's still over 3 db.
http://www.smarthomeusa.com/Shop/cvc...s/Item/C-0202/
Unless you've come up with a passive way to get more out than you put in to begin with, we're stuck with the fact that we're faces with that loss.
I really can't understand why you have to obfuscate this matter rather than simply state the facts. That tends to be a common trait with this hobby.