Hi all,

I haven't read every message in this thread, but I think there's a variant of the D controller which has audio output. I think it's version C, but stand to be corrected on that.

Cheers,

Terry

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Terry Robinson B.Sc
82 Albert Rd.
Crosshill
Glasgow
G42 8DR
Mobile: 07771 610002
Web: www.describe-online.com

  ----- Original Message ----- 
  From: Mike Duke, K5XU 
  To: [log in to unmask] 
  Sent: Sunday, April 19, 2015 10:40 PM
  Subject: Audible Direction Indicator


  Instructions for building one were in a QST Hints and Kinks in either 
  1979, or maybe 1980.

  I think this is the same circuit that HandiHams built.

  To connect the circuit, all you have to do is determine which terminals 
  on the back of the control box receive the voltage change caused by the 
  changing value of a pot in the rotor which turns along with the 
  antenna. For my HD73, I believe that is terminals #2 and #5, but don't 
  quote me on that.

  The circuit is basically a wheatstone bridge that is connected across 
  the two control box terminals that receive the voltage change from the 
  pot in the rotor to drive the meter in the control box. The wheatstone 
  bridge in turn drives an audio osilator. When the voltage on the meter 
  is equal to that of the reference circuit in the bridge, the tone is 
  nulled out.

  By having a scale, or at least a few tactile marks in key places around 
  the knob of the pot in the reference circuit, you can set the pot so 
  that you get a nul when the antenna is pointed in the direction you want.

  Of course, the scale must be set up with the help of someone who can 
  read the meter on the control box. But once this is done, you are in business.

  I may have the schematic somewhere. If I can find it, I will put it 
  where folks who want it can get it, and post that information here.

  -- 
  Mike Duke, K5XU