On 3/1/21 12:31 PM, john@kk9a.com wrote:
I have never seen anyone put two SteppIRs on the same mast but the 7 ft
separation is more than adequate for operating on two bands simultaneously.
One of my homebrew 20m beams also has a commercial 40m beam mounted on the
same boom and there is no interference except on the harmonic.
One potential threat I'll mention..
Say you're transmitting on antenna 1 on, say, 15 m, and using antenna 2
on 20 m.
You then command antenna 2 to 10 m because of a band change. During the
time that the antenna is changing the element lengths, there will be a
short(TBD) time when the element lengths on antenna 2 are close to the
element lengths on antenna 1, and the antenna to antenna coupling will
greatly increase, especially if they're pointed the same direction.
(the pattern on antenna 1 will probably go wonky too, because of the new
"parasitic elements" on the antenna)
If I did the analysis, and the levels looked scary from a receiver burn
out standpoint, I'd arrange the switching logic so that Rigs don't
connect to their antenna until they are in their final configuration.
(and, also, that you have a lockout to prevent you from setting two
antennas to the same band)
7 feet is a pretty small fraction of a wavelength (about 1/5th) , even
on 10 meters.
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