Repeater antenna separation

[wqzw301]

I'm planning a new antenna system and mast for my repeater.

Got it in my head, that I want to try separate tx / rx antennas. Vertically 

So, I've looked up the charts and used the CommScope antenna separation calculator.

Vertical separation would be 20' - (70db).  Which is ok... My rx antenna would be 45' and my tx antenna would be 25'. 

But does that take into account the isolation I have at the transmitter? 

I have 3 1db wacom  cans on the rx side 

2 wacom 1db cans on the tx side,  plus a circulator.

I will lose 80db without my duplexer. But I can make that up with some more band pass / band reject cavities.

So, can I move the tx antenna a little higher up on the mast and make up iso db's at the transmitter,

Also my tx antenna will be 6dbd and my rx antenna will be 1/2 wave stacked completely vertical. 

Please and thank you for any help

 

 

 

 

[gortex2]

Thats an awful lot of equipment and feedline for a UHF repeater at 45' off the ground. Are you on a 5000' mountain ? If not I dont see why a decent duplexer would't work better than trying to be separate antennas. Normally when separate antenna's are used its adding multiple TX and RX channels to a system. For a single GMRS/ UHF repeater I'd just use a duplexer and a single antenna. 

What is the reasoning of using 2 antenna's vs one ?