if it's a short run I would just use rg8x (mini)
Make that a very, very short run. Six meters is about the point where things start to take a turn as to what to use for feedlines. Without a doubt, use the very best and lowest loss feedline you can afford. On 6m RG-58 has almost 4 dB loss per 100 feet while Belden 9913 has just 1 db per 100 feet. I use Andrew LDF4-50 which has a bit less than 0.5 dB loss per 100 feet. It's not cheap but I need about 160 feet to reach the antenna so loss is a factor due to length for me.
Maybe 75 feet. Less than 100 feet.How long will your run be?
Nothing yet for the 6 meter antenna.Or from the other end of that sort of question... what kind of coax do you have?
- 'Doc
I would go with LMR 600 or half inch Heliax if the run is 100' or more. It is desirable to keep line losses below 1 db on 6 meters and above, if possible.