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Author Topic: Mobile antenna question  (Read 574 times)
N4NOO
Member

Posts: 106




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« on: April 09, 2013, 08:02:26 AM »

I have a screwdriver type HF antenna on my car and I have a matching coil at the base which works very well on some bands.  I need to add a coil which I will use on other bands.  I will switch these coils into or out of the system with a relay on each coil.  My question is weather the relay should switch the antenna end or the ground end, in or out of the system.
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M6GOM
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Posts: 874




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« Reply #1 on: April 10, 2013, 02:43:47 AM »

Alter your existing matching coil. It should provide an acceptable <1.5:1 SWR on all the bands. Don't get hung up on trying to get a 1:1 SWR operating mobile.

If you can't get an acceptable SWR below 1.5:1 on all bands, look at your mounting and bonding.
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W5WSS
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Posts: 1631




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« Reply #2 on: April 10, 2013, 07:45:12 AM »

The screw driver should tune the bands designed for when mounted reasonably on a vehicle.

I presume the tap and coil, door knob capacitor is for a lower band?

Base loading? The hot lead at the tap should be switched to bypass for normal operation of the screwdriver design bands. Are you Not sure how to do this?

The question remains have you already determined that the installation is adequate for the service utility of the system without the need for a matching network?

If you can't get an acceptable swr below 1.5:1 on all bands, look at your mounting and bonding.

73
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