[Milsurplus] DF and ADF nulls

[Michael A. Bittner]

I remember the ADF needle "hunting" phenomenon on distant stations when flying the PBM-5 over the Gulf of Mexico out of Corpus Christie, TX back in 1956.  Not sure exactly which ADF was installed in that aircraft - ARN-6 or -7?.  Mike W6MAB
  ----- Original Message ----- 
  From: Mark 
  To: Milsurplus at mailman.qth.net 
  Sent: Sunday, April 14, 2013 7:58 PM
  Subject: [Milsurplus] DF and ADF nulls


  "The MN-22 and MN-40 are really beautiful. I wonder if the loop null is
  really as good as the indicator."

  Depends on signal strength. Weak signal broad null. Strong signal sharp null. 

  I spent years using an ARN 7 for nav on a commercial fishing boat. If the loop compensator was set up properly (to compensate for bearing distortion caused by boat rigging) it was amazingly accurate and stable on strong station ground wave bearings. I'd see +/-one degree on the old Farallon Island NDB on 318 KHz when within a few miles. 80 miles out it could be +/- ten degrees and swinging side to side even when my heading was steady. 

  When in heavy seas a manual DF was not very useful due to heading yaw. Trying to get a reliable manual bearing was very hard under those conditions. An ADF made it a LOT easier. 

  Mark
  AF6IM
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