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Antenna rotator AR-300 XL review

Antenna azimuth indicator

Are you using a cheap antenna rotator like AR-300? I have three these rotators and on one I have found a difference between the real antenna azimuth and indication. After few hours was the difference 80 degrees. Rotator, especially rotator with a top bearing is constructed well and could be used also with a larger antenna as a HF monoband yagis for higher bands or smaller tribander.

I have developed simple antenna azimuth indicator – aziumth measurement. It’s a simple Wheatston’s bridge where is used a pot attached to the rotator tube as sensor. Voltmeter is showing directly azimuth in degrees from 0 to 360.
I am using AR-300XL under the roof, so it is easy to join rotator tube with a potenciometer. See the picture below for details. Use a good quality pot. I have used 100 ohms linear Aripot. Used drive transform 360 degrees into the 180 suitable for pot.

The rotator case isn’t fully waterproof but you can still built-in pot if you would like to mount the rotator on the tower. I am recommending to turn the wire from the main gear in the rotator – you got an advantage of the turn more as 360 degrees and avoid the gear breaking.

The Wheatston’s bridge is simple. I have used the Electronic WorkBench software to develop the bridge. The schematic diagram is showed with the 5V power supply and output voltage 3,6mV. Potenciometer is marked R4. Other pots are multiturn types – calibration is much easier with them like with cheap pots. Resistors across the bridge were used as a voltage divider. If you would like to have 36mV output, use 12V power supply and connect the voltmeter on the bridge directly (R2 and R3 slides).

The cable from sensor is wound on the ferrite core in the box (three turns or so) as a prevent for RFI.

Schematic diagram of the antenna azimuth indicator

Schematic diagram of the antenna azimuth indicator

There are several ways how to display the value from the sensor. Very nice circle azimuth indicator is described on the OK2KKW’s website. It can be used also the pointer instrument with new scale in degress. I have intend to use a LED voltemeter but I can’t found it in the local shop. So I bought a cheap LCD voltmeter module for five euro. If your PC skills are high, you can measure azimuth with computer, e.g. through the serial port.

Also I am recommending to block mechanically azimuth measurement in the control box. Bottom is a hole with bearing. I have put there a small wooden block. You can get an advantage of turning more than 360 degrees and preventing the problems with dead point of the rotator.

Calibration is a time-consuming procedure. One suggestion – turn antenna on the north and measure with ohmmeter resistance of pot. Build a resistor with this value (use a pot or combination of resistors). Now turn the antenna to 360 degrees, measure again the resitance and build the second resistor.

Now connect to the bridge first resistor and try to make balance with the pots – voltemeter must show zero. Now change it for second resitor and with R1 set on voltemeter 36mV or full scale on the pointer instrument. Check again zero and turn litlle pots – if needed. All post are affecting the bridge so do the calibration again and again until it is zero and 36mV as needed.

LCD voltemeter showing 99 degrees

See the pictures for construction. I have used a metal box which is also used as stand for control box. In the wind is indicator changing digits frequently, it’s OK. Antenna is really moving right and left in the wind.

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DX World of Ham Radio

DX News / Choice Snippets of Info

CX1F - San Gabriel Island, SA-057

Activity from the San Gabriel Island (SA-057) under the CX1F callsign, postponed the last month because of weather and sea conditions will finally take place on December 13th. QRV 80, 40, 20, 15, 10 and 2 meters, propagation permitting. QSL via CX2FAA

eHam.net News

eHam.net Newsfeed

DX News -- ARRL DX Bulletin #50:

This week's bulletin was made possible with information provided by NC1L, the OPDX Bulletin, DXNL, 425 DX News, The Daily DX, Contest Corral from QST and the ARRL Contest Calendar and WA7BNM web sites. Thanks to all.

KN4LF Propagation Forecast #2008-35:

Ham Operators Connect Plantation to World:

PLYMOUTH - The Whitman Amateur Radio Club conducted a two-day special event at Plimoth Plantation the weekend following Thanksgiving. Twenty-two area amateur radio operators (or HAMs) set up six base stations and portable antennas and exchanged contacts with 216 other amateur radio operators in 32 states, 8 foreign countries and 3 Canadian Provinces, according to club President Paul Burbine (N1VTI). The HAM operators spread the word about Plimoth Plantation over the airways, explaining about the living museum and the amazement of visitors who interact with interpreters trained to explain the realities of early Colonial life, in the language of 17th century without acknowledging life beyond the 1620s.

ARRL Amateur Radio News

The National Association of Amateur Radio

ARRL HQ Welcomes New Membership Manager

The ARRL is pleased to welcome Membership Manager Diane Petrilli, KB1RNF, to the Headquarters staff in Newington. Petrilli's key areas of responsibility include programs and activities that directly affect membership growth, engagement and retention. Petrilli is taking over the position from Katie Breen, W1KRB. Breen left in October.

ARRL Continuing Education Online Course Registration

Registration remains open through Sunday, December 21, 2008, for these online course sessions beginning on Friday, January 2, 2009: Amateur Radio Emergency Communications Level 1, Radio Frequency Interference, Antenna Design and Construction, Technician License Course, Analog Electronics, and Digital Electronics.

ARISS Celebrates International Education Week

With all the educational opportunities the Amateur Radio on the International Space Station program (ARISS) provides, it's no wonder that the organization has captured the attention of the US Department of Education (DOEd). According to ARRL ARISS Program Manager Rosalie White, K1STO, the DOE has been tracking ARISS's activities for a long time: "The Department of Education invited ARISS to help celebrate the ninth annual International Education Week (IEW) by coordinating three contacts with the International Space Station (ISS) during IEW, November 17-21. How could we say no?" International Education Week is a joint initiative of the US Department of Education and US Department of State.

Make More Miles on VHF

Updated: 2008-12-03 at 20:17 UTC

More info at www.MMMonVHF.de

IQ3AZ/p

A group of IV3-operators will be active in MS from JN66 square during Geminids shower, taking part in BCC MS-Contest The group will try as well having a MMMonVHF DXBlog online to spread infos (NO LOG during Contest!).

EI/ON5GS/P

Dirk, ON5GS, will be qrv serveral days from my "berlingo" shack with 4x4el vertical stack and 200W during BCC MS-Contest. He try setup as well a MMMonVHF DXBlog to spread infos (NO LOG during Contest!)...

Southgate Amateur Radio Club RSS Feed

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Amateur Satellite Beginners Slides

The Powerpoint slides used in the satellite beginners session at the Leicester Amateur Radio Show, are now available on the web

CubeSat-sized linear transponder developed

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DX News from the ARRL

The American Radio Relay League's round-up of the forthcoming week's DX activity

MØMCX

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160m SSB Club Calls Contest - November 2008

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Waterproof PL259 connectors for Ecoflex

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Oliver's Blog

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How to configure postfix to reject spams

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GB0SH 2008 is back!

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