when receiving on channel 14 i have a high pitch tone coming in while someone is talking. this only happens on 14 .i have tried different mikes, checked swr ,soldering joints, grounds.this radio has never been worked on and still looks news.I could live with this high pitch tone but channel 14 is our call channel and its no getting rid of this unless you turn back the squelch or the rf gain to the point you can not hear.I hope someone may have dealt with this problem and have a solution to this. i forgot to mention this it happens on my base antenna as well as my wilson mobile antenna.
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galaxy dx 44v high pitch or ringing sound
- Thread starter lost bandit
- Start date
it is heterodyning.
just like when two stations key up on the same channel at the same time, you get that whistle sound.
channel 14 just so happens to be harmonically related to many wireless devices in use these days.
most likely, there is already a weak constant signal in your receive on channel 14 from a wireless keyboard, wireless mouse, or any number of wireless devices in your immediate area.
when someone keys up, they are competing with this "signal" and you hear the heterodyne.
if it's coming from your house, then you can simply turn off the offending device.
however, if it's coming from a neighbor or close by business, then it's going to be tougher to abate.
channel 14 is a pretty unfortunate channel to have as a call channel these days.
hope this helps,
LC
just like when two stations key up on the same channel at the same time, you get that whistle sound.
channel 14 just so happens to be harmonically related to many wireless devices in use these days.
most likely, there is already a weak constant signal in your receive on channel 14 from a wireless keyboard, wireless mouse, or any number of wireless devices in your immediate area.
when someone keys up, they are competing with this "signal" and you hear the heterodyne.
if it's coming from your house, then you can simply turn off the offending device.
however, if it's coming from a neighbor or close by business, then it's going to be tougher to abate.
channel 14 is a pretty unfortunate channel to have as a call channel these days.
hope this helps,
LC
What you are hearing is a built-in "feature" of all 8-band Galaxy/Connex/Superstar radios that use a 13.560 MHz crystal in the radio's PLL circuit. This is the crystal that's connected to the clarifier in models that provide that knob.
All quartz crystals produce some harmonic energy, in addition to the main frequency marked on the crystal. The second harmonic of 13.560 is 27.120, halfway between channel 13 and 14.
It will "leak" out of the PLL circuit into the receiver and be heard as a carrier. The common textbook name for this fault in a receiver is a "birdie", because of the whistling heterodyne sound it usually causes.
If you really need to use those two channels, changing the crystal will move that birdie to a frequency you don't use. The next "step" up in crystal frequency that will line up the channels properly is 14.01 MHz. You will lose the lowest band "A", because each band will now be moved upwards. Your "F" band will now be higher in the 10-meter ham band. This simply moves all 8 bands up by one. The birdie will now be heard at twice this frequency, or 28.020 MHz. You probably won't care about it located there.
Using a 14.460 crystal will move all eight bands up by two.
A 14.910 crystal will now leave the radio with only one band below channel 1, but with coverage well up into the 10-meter ham band on "C" through "F".
And a 15.360 crystal will eliminate all your lowers, making the legal 40-channel CB frequencies band "A".
RF Parts stocks some or all of those crystal frequencies.
73
All quartz crystals produce some harmonic energy, in addition to the main frequency marked on the crystal. The second harmonic of 13.560 is 27.120, halfway between channel 13 and 14.
It will "leak" out of the PLL circuit into the receiver and be heard as a carrier. The common textbook name for this fault in a receiver is a "birdie", because of the whistling heterodyne sound it usually causes.
If you really need to use those two channels, changing the crystal will move that birdie to a frequency you don't use. The next "step" up in crystal frequency that will line up the channels properly is 14.01 MHz. You will lose the lowest band "A", because each band will now be moved upwards. Your "F" band will now be higher in the 10-meter ham band. This simply moves all 8 bands up by one. The birdie will now be heard at twice this frequency, or 28.020 MHz. You probably won't care about it located there.
Using a 14.460 crystal will move all eight bands up by two.
A 14.910 crystal will now leave the radio with only one band below channel 1, but with coverage well up into the 10-meter ham band on "C" through "F".
And a 15.360 crystal will eliminate all your lowers, making the legal 40-channel CB frequencies band "A".
RF Parts stocks some or all of those crystal frequencies.
73
thanks for so much great information from two wonderful techs .its amazing the skill you all have.thanks again.