[Milsurplus] BC-AO-229 questions

[Mike Morrow]

BC-Ax-229 receivers through BC-AP-183 had provisions for connecting a loop antenna.  The Direction Findind Indicator plugs into the DFI jack on the front panel.  The DFI jack is normally closed, in series with the cathode path to ground for the first two RF AMP stages.  A 0.0 to 20 mA meter plugged into the DFI jack indicates this cathode current and may be used as a signal strength meter when AGC is turned on.  Minimum current is a strong signal...max current is weak.

Other than this, the AO circuit is almost identical to the more common AR and AS models.

Mike / KK5F


-----Original Message-----
>From: John Franke <jmfranke at cox.net>
>Sent: Jul 9, 2020 1:38 PM
>To: Military Surplus Mail List <milsurplus at mailman.qth.net>
>Subject: [Milsurplus] BC-AO-229 questions
>
>The BC-AO-229 TRF receiver has a few oddities when compared to many of the other BC-229 series receivers. I am looking for schematics and possible descriptions of two. The first is the "DFI" jack on the lower right-hand corner of the front panel. I assume DFI stood for "direction finding indicator" and was possibly used when the the receiver was coupled to a DU-2 loop antenna. Maybe the DFI was just a AGC signal strength meter. The second involves a switch on the left-hand side of the front panel below the single antenna post and is labeled "A-L." I was thinking it was used in conjunction with the DFI. I am guessing the antenna post was connected to the DU-2 when doing direction finding and the switch changed the antenna matching for the receiver frontend. And, in the A position the receive matching network was what one would expect with a normal BC-229 setup. 
>If anyone can provide schematics or other information to help clarify, I would be grateful for the assistance. 
>
>John WA4WDL
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