Henry can you please explain gain balancing an antenna system
Radio techs do this all the time without sophisticated equipment. Often a transmitter will be made up of an exciter that makes a few watts, an intermediate PA and then the final amplifier.
Gain staging these hybrid tube/transistor beasts was not as hard as it may seem. You would hook your wattmeter (almost always a Bird) between the stages and peak the matching circuit for max output. This guaranteed a good impedance match between the stages.
Then you backed off the power control until you saw a loss of power on the next stage. This was important, you only wanted to drive each stage as much as was needed to provided full output. FM transmitters produce full power all the time as the carrier is deviated so headroom was not an issue. If you drove a stage too hard the output would get "nasty" without a significant rise in output power. You would, if you paid attention see the input current rise as the amplifier was producing a broader signal.
Later, when service monitors had spectrum analyzers as standard equipment you would see the noise floor rise as input power was increased.
This is the exact same principal. With an RX multicoupler you only want to makeup losses in the distribution network. You can't suck signal out of a line that doesn't exist. You can however bring up the noise floor and compromise S/N ratio.
There is a serious analog here to AF gain staging. Concepts are similar and the goal is the same.
Lastly, staging a combiner is also a similar exercise. Increase transmitter output only to compensate for the loss of the combining network.