Coax size between repeater and duplexer

[Defender92]

I’m thinking I’m going to build a repeater. I’m making a shopping list. I want to use two Kenwood tk-8180 radios and a mobile Celwave 633-6a-2 duplexer. 
 

I keep seeing images of people using what looks like rg400 coax from the radios to the duplexer. I used lmr400uf ultra flex from DX Engineering to connect my base station and I have some left over. But the lmr400uf is still stiff for such a small distance from radio to duplexer. 
 

If I use a smaller coax like the rg400 vs the lmr400uf will it make that much of a difference?

 

thank you!

[SteveShannon]

47 minutes ago, Defender92 said:

I’m thinking I’m going to build a repeater. I’m making a shopping list. I want to use two Kenwood tk-8180 radios and a mobile Celwave 633-6a-2 duplexer. 
 

I keep seeing images of people using what looks like rg400 coax from the radios to the duplexer. I used lmr400uf ultra flex from DX Engineering to connect my base station and I have some left over. But the lmr400uf is still stiff for such a small distance from radio to duplexer. 
 

If I use a smaller coax like the rg400 vs the lmr400uf will it make that much of a difference?

 

thank you!

Use one of the many coax loss calculators to see if the loss for that length is acceptable to you.