Topband: bias tee

[Tom W8JI]

>I am using my coax to feed 12 VDC to my remote RX antenna locations, using 
>a traditional bias tee, but am having some trouble with performance.  I'm 
>using 100 uH Radio Shack chokes in my bias tee, and am wondering if perhaps 
>that is insufficient inductance for 160 meter operation.  If so, what would 
>be an appropriate value?

100 uH should be more than enough inductance if bypassing is good and the 
choke has proper current rating headroom, and also have a properly 
constructed box for the bias T that allows good bypassing.

Of course we should remember chokes have more than an inductance. They have 
a series resistance that varies with frequency, and a current rating for 
heat, and a flux density characteristic that changes inductance or clips 
waveforms if they have an iron core.  The flux density is a function of dc 
and ac currents through the choke, or you could look at it RF voltage across 
the choke and DC or low frequency AC currents through the choke.

Any answer is meaningless unless we know:

The type of issues you have
The application in detail
The type of bypassing in the bias T
The physical layout, especially for ground paths
The bias current

73 Tom