Maybe my answer was not clear enough - anytime you make or break a connection between the coax and the shield and a connector - some loss occurs.

When you start stacking one adapter on top of another adapter and when you use a more lossy coax - the losses multiplies.

As a example - lets say you spent $6000.00 to put up a 100' tower, a SteppIR DB antenna and a cheap Ham IV rotor and then you skimped on the coax and used some cheap Radio Shack RG 8 - open braid wire

Lets say the beam antenna produced 12 db of gain on 20 meters and the coax threw away 3 Db in 100'. Lets also assume you used a good Amphenol PL connector and one connector on each end, had one half of one Db of loss.

You just threw away 4 Db of signal.
Knowing that 3 Db / actually 2.85 is equal to a loss of 1/2 the signal - its like substituting the SteppIR DB antenna for a cheaper model.

Now - we are not just throwing away receive power, we are also throwing away transmit power / and i'm not even going to get into the costs associated with that.

To take it one step further, lets say we put up a 440 MHz repeater and we use the same Radio Shack RG 8 coax and the same PL connector @100'...

What was only 3 Db of loss at 14 MHz is now 16 Db of loss at 440 MHz.
So we go to a better grade of coax / probably hard line, and we use $150.00 connectors on each end.

We still need to concern ourselves with loss.

If we throw away even 1/2 of 1 Db with every connector and we have one connector at the top of the tower, another connector at the ground plate, another connector at the bottom of the tower, another connector on the wire going to the transmitter building, another connector at the transmitter building - before the coax enters the building, another on the other side of the ground, another at the duplexer, another at the transmitter - it isn't very long before all those connectors adds up.

When you get into Microwave frequencies it gets even worse.

Look at the cost of a 1000 watt amplifier for 14 MHz and compare that cost to a 100 watt amplifier at 2.4 GHz and then tell me which is cheaper...