Walter Salmaniw wrote: > This is fascinating, Rick. You're absolutely right. In your > preferred method, watching the meter is of no use, and it's simple by > ear alone. In fact this may indeed be the preferred method of using > a phaser effectively. I'm experimenting now nulling 1200 CJRJ to > hear a Gospel program underneath without any difficulty. > Thanks!........Walt.
I'm glad to be of help Walt. One other thing about DXing with the AGC off and the receiver set up as I described is that the receiver will no longer adjust the AGC to follow the level one of the stations on the channel, causing the others to decrease in volume as one of the stations rises and lowers in signal level. This makes for easier listening to stations on the channel. Additionally, sub-audible heterodynes on a channel can also cause this effect, and at times when these are present the AGC will sometimes try to follow these hets and add an additional layer of volume variations or fluttery sound to the audio. Sometimes the effects of turning off the AGC on a channel with or without sub-audible hets can be startling. You do naturally have to adjust the RF gain control up and down occasionally to keep the volume where you want it and to compensate for slow signal variations over long periods of time, but usually this does not require much attention. The band can be surprisingly stable lots of times. One other thing I have found effective at times, is to have the ability to reverse the phase of one of the earpieces in a pair of headphones. Adding a switch to reverse the phase of one earpiece is the easiest, but there is also a way to place the two earpieces in series and effect the same phase shift. The audible effect of putting the phase of one earpiece 180 degrees out of phase from the other is to cause the audio to sound like it originates inside the head rather than in front of it. Sometimes this causes a jumble on a channel to seem to be easier to understand. Other times it either makes no difference or makes things worse. It is handy to have the ability to flip a switch and see if flipping the phase makes a difference on a particular channel. I've managed to get some IDs this way that I would never have been able to pull out normally. You can disassemble one of the earpieces on a pair of headphones and add a miniature double-pole double-throw switch to do the phase reversal. Alternately, or to try this out, if you use a pair of jumper clips and a bare plug into the radio, you can connect the sleeve and tip of the radio plug to the tip and ring of a set of stereo phones, thus placing the two sides of the phones in series and out of phase with each other. The sleeve is not connected in this way of reversing phase. I built a switchable box to do this a few years ago and it works nicely, though there is a slight decrease in volume level when series connecting the phones to achieve the out of phase condition. It's better to add the switch to the headphones, if possible. I may build a phase reversal box using a pair of transformers to do the job someday, and reverse one of the secondary windings to reverse audio phase to one side of the headphones. I believe that Heil or one of the other headphone makers offers a pair of headphones already fitted with a phase reversal switch. Any tool you can use to make intelligibility better is worth experimenting with. Rick Kunath _______________________________________________ IRCA mailing list [email protected] http://arizona.hard-core-dx.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
