The diode problem can happen on any band.
At one time I had the Midland Repeater (W8KEA) located here in my basement.
The antenna was a commercial vertical located on top of my old 90' tower.
The tower was guyed with EHS broken up with insulators. I don't remember the
dimensions now, but the guys started with short sections at the top and
increased in length as you went down.
The system worked well for some years, but we started having desense
problems, and tuning the cans was a night mare even with a spectrum analyzer
and sweep generator.
One day I discovered that sliding an 8" screwdriver along one of the
metallic guy lines with would create enough noise to completely wipe out a
50 watt mobile using a colinear on top of an SUV less than 5 miles distant.
That was at the bottom of the guy which was grounded at the bottom and had 4
insulators between it and the tower. IIRC that piece of the guy was
*somewhere* around 30 feet long.
73
Roger (K8RI)
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