"MC" wrote in
t:
I've just replaced my old cable with some nice shiney new 50ohm coax
attached directly to my 100+ feet of longwire. As I still want to suck
that little extra out of my antenna, I want to add a balun but I am
confused with this transformer ratio stuff. I realise that a long
wire has quite a high impedance. However, should I go for a 1:4 or a
1:10 ratio balun. If I went for the 1:10 would it be overkill and
will it make any difference over the RF if I only had a 1:4. I ask
because I can get a 1:10 a lot cheaper than a 1:4.
Confused? I am 
MC
1:9 is ideal for a longwire (ideal impedence is 450 ohms, matched to 50 ohm
coax, so 50:450 = 1:9), so go for the 1:10. The 1:4 is for something with
lower impedence than a longwire.
Not all baluns are created equal, however. What frequencies are they rated
for? This will depend on the turns count of the windings and also on the
ferrite material.