[Milsurplus] Improving RU Selectivity.

[arc5@ix.netcom.com]

    Was listening to a 75-meter AM QSO with the RU-15 receiver this morning. There were the usual SS-SOBs needlessly crowding the AM Window.  Made a short video of how easily one can improve the selectivity of the receiver with just a piece of wire and a few minutes spent fiddling with it.
Ran a wire from the antenna post to near the third tube from the rear.  Adjust how much wire, how near the tube.  Fine-tune with the ANT TUNE knob.  It's touchy- too much coupling will motor-boat.  Regen will also pull the tuning some so you'll need to zero-best.  When you find the "sweet spot," you can easily hear the "rushing noise" as you tune across each sideband of the AM signal.  In fact, you can get it TOO narrow, distorting the audio.  The improvement can be dramatic.  Here's the video:
https://goo.gl/photos/wBK2dKmkFukYjR3A9

73 Dave AB5S
P.S. Once you get it narrowed on a carrier, it's much easier to zero-beat the BFO correctly.
    Sent from my Ain't Smart Phone.



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20170522/0568284f/attachment.html>