Samuel Hunt wrote:
Do these things actually work?

I have a 2m 5/8 wave that I use mobile, and am told that a 7/8 wave will
give more gain. Can anyone confirm?

Well, the 7/8 wave vertical has about 1-1/2 dB more gain than a 5/8
wave, if you measure that gain at the angle at which each antenna's
radiation is greatest. The problem is that while the 5/8 wave antenna
radiates most strongly toward the horizon (assuming a large ground
plane), the 7/8 wave radiates almost nothing at the horizon. Its
radiation is maximum at about 40 degrees above the horizon. Great for
contacting aircraft at a particular distance, but very poor for general
line-of-sight and repeater use. At the horizon, the gain of the 7/8 wave
is about 20 dB less than that of the 5/8 wave. This assumes a large
ground plane, and relative performance will vary depending on the
frequency and installation. But you can count on the 5/8 being much
better than the 7/8.

I'm told also that I can just take the 5/8 wave out and stick the 7/8 wave
in and it will load up. I doubt this personally - can anyone tell me if it
needs more or less inductance?

Considering the lousy radiation pattern, I can't see why anyone would
want to use a 7/8 wave vertical.

Roy Lewallen, W7EL