Topband: Trap for 160m/80m inverted L
ford at cmgate.com
Fri Dec 9 15:30:31 EST 2005
> When you need to share a single radial system and a single high support on
> both bands, it is possible to feed two inverted-L's at a common feedpoint,
> as long as the vertical wires of the two antennas are separated by enough
> distance to reduce coupling to manageable level -- 24 inches works fine.
> The top wires should be pulled out in different directions.
I use such a system but with a grounded shunt fed tower and two separate shunts. However, I had to incorporate a vaccuum relay on the 160M hat wire. My two 'hats' are 180 degrees apart (one north and one south). The 160M hat wire worked fine right out of the gate. But on 80M, that wire caused all sorts of matching problems. The relay eliminated the problem. I run up to about 1KW using an RJ1 relay with no problems. However, as a summer storm approaches, I hear the unconnected hat wire arching--the repeated snapping increases in frequency with the longer wire floating. Perhaps a choke would be in order to pass the static DC back to the grounded tower.
ford at cmgat.com
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