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Friday, May 2, 2014

Bert's EMRFD Direct Conversion Receiver



Very nice Bert.  Sounds great.  I like the pill bottle coil core.  Lew McCoy used them in his designs. I do think that air core coils do provide better stability than ferrites or iron powder.   I kind of like the SW broadcast background music.  I also like the internal 9V battery.  Glad to see someone else resurrecting an old DC RX project.  


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2 comments:

  1. Thanks Bill, I thought you might like hearing about it.

    I've since fixed the breakthrough problem (I think?) by improving the filtering. While some might enjoy the background music, it was getting out of control! I also found out I'd put the little 4.7 uF cap for the LM386 onto the NE602 by mistake! So the audio is now up to strong levels. Another mod was to transform the 50 ohms from the antenna to the ~1.5 kohm expected by the NE602. This boosted signal dramatically as well. I'm now left with a little rig that sounds very decent on 40m, has no out of band junk and is fun to have on in the background in the shack.

    A big thanks to the EMRFD guys who inspired me to try this years ago. I think this was a nice starter rig, and as you gain knowledge you learn how to fix some of the minor shortcomings and it's a lot of fun.

    ReplyDelete
  2. I too like the emrfd radio and video! Thanks and 73 de chas ai4ot

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