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Author Topic: Auto versus manual screwdriver control?  (Read 438 times)
KB2PSM
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Posts: 8




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« on: March 02, 2004, 06:27:02 PM »

I've been planning to replace my Outbacker antenna on my Winnebago Eurovan Camper with a screwdriver.

My radio is the Kenwood TS-2000 and it is easy to add an automatic antenna controller such as the AMAC.  The Tarheel antenna seems to do quite well with this setup.

The High Sierra line uses a manual tuner and is another well-received antenna.

On the surface, the automatic control is very desirable, as band-changing with as little distraction as possible is a good thing in the mobile.

HOWEVER...

some friends reported that using a manual tuner is so easy and obvious, that it would require little effort, time and distraction while on the road.

I am curious about the experiences of other screwdriver operators.  Your insight might help me to narrow down my mobile upgrade options.

Thanks,
Rob KB2PSM
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K0BG
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« Reply #1 on: March 03, 2004, 10:52:30 AM »

Driver distraction caused by telematics is the number one cause of crashes according to the NHTSA. Automatic control is always preferred. Incidentally, Hi-Q also offers a model with a built-in magnetic switch; a prerequisite for automatic control. You could also look into an auto coupler like SGC's.

Alan, KØBG
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K5LXP
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« Reply #2 on: March 03, 2004, 10:57:31 AM »

It's all a matter of personal preference, and how much the convenience of touch-free operation is worth to you.  I built my manual interface for about $20, and it does require a glance away from the road to do the last "bump" or two up or down to get the best match.  I've been running my setup for a few years like this and it's secondhand to me.  I don't see a compelling reason to upgrade to an automatic but it would be nice to have.  Others may have input on potential pitfalls of automatic units, I doubt they are without their faults or operational considerations.

Mark K5LXP
Albuquerque, NM
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K0BG
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« Reply #3 on: March 03, 2004, 02:31:03 PM »

Marks comments reminded me of something. Last March I was at the Midland, TX hamfest and a guy there was selling a combination manual screwdriver switch and audible VSWR bridge. I didn't ask what it cost, but it shouldn't be too hard to duplicate it.

Alan, KØBG
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K5LXP
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« Reply #4 on: March 03, 2004, 08:12:11 PM »

The T-hunt guys use audible signal strength meters, would be a simple matter to connect that oscillator circuit to a directional coupler to detect SWR null audibly.

Mark K5LXP
Albuquerque, NM
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W7DJM
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« Reply #5 on: March 07, 2004, 03:02:22 PM »

I don't have the magazine article (CQ, QST) but there was, is, and are projects for the blind envolving audible swr meters.

Another way would be to build a phase detector instead of swr, allowing you to use a zero center meter, and at a glance tell whether to go up or down.

The problem, of course, with a conventional swr meter is if, say you are going UP with the antenna, and have bumped UP past the swr dip, you may still go on up a ways before you realize this.
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