[BC] Ground system

[Mike McCarthy]

On 2/12/2012 4:33 PM, Craig Healy wrote:
>How about this?  A tall tower, maybe 500' commonly used by 50kw FM stations.  To add an AM to it, use a skirt feed.  Rather than at ground level, put the feed up at the lowest guy wire point.  Bond those guy wires to the tower and put a long fiberglass insulator a quarter wave or slightly more out from the tower. Those become the radials.  Insulate all the above guy wires just as at any AM station.

I have asked the same thing and there is a reason it's not done and/or permitted.  I had such an AM of a FM tower situation once and I seem to recall it something to do with the radiator height not changing all that much, but making the rest of the installation more complex and unstable.

The same premise would apply to diplexed operations where the tower is really too tall for a 2nd station ( I have one of those!!!).

You would need to run a MoM study to really nail down the tradeoffs.

MM