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Chuck Rippel

Copyright: 1996, 1997, 1998, 1999, 2000, 2001, 2002 

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The R390A/URR

Ultimate Performance, General Coverage AM & CW Receiver

R390A/URR Receiver Site Pages Accessible from Left Hand Navigation Bar

Audio from the Diode Load Pickoff

Audio from the R390A obtained from either the LOCAL or LINE outputs is good, but nothing to brag about.  Indeed, the receiver is capable of some of the best audio obtainable from any vintage, hollow-state receiver. 

The BEST audio from an R390A can be gotten by sampling it from the rear-panel, ``DIODE LOAD" pickoff point.  The DIODE LOAD jumper is electrically located directly after the receivers detector and has a frequency response  limited only by the selected IF filter and detector circuit.  The simple circuit pictured below is nothing more than a 470K 1/2w resistor in series with an 8ufd, non-polarized capacitor.  One end of this network is connected to the rear panel DIODE LOAD point and the other, to the center conductor of a standard HI-FI phono cable.  In the picture below, the cable shield is grounded to the mounting screw used to hold the barrier strip which mounts the components. The phono cable is then plugged into the AUX or TAPE input of any standard serero or mono amplifier.  The 8 kc (really 11 kc) filter, your choice of speakers and tone setings can provide outstanding audio at room filling volumes.

Since the DIODE LOAD jumper is left in place and the additional circuit does not in any way load the detector, you can still also operate the receiver as normal using either the LOCAL or LINE audio outputs.