Dmans,
you will find many references to "white noise" when it comes to RCI/galaxy style radios. (remember when we used to just call them all 'exports'!?)
the problem with all of these references is that many of the threads will tell you to de-tune a certain coil to reduce the white noise, but since this is done in so many chassis with different part numbers, you can read the wrong thread and end up de-tuning the wrong coil in your radio.
for your 2970DX, the coil in question is L5. its the tuning can before the RF front end amp transistor.
after peaking the receive (using a SINAD meter! it's super important in these type radios) go back and unplug everything from the antenna socket on the radio.
set the radio volume to allow you to easily hear all the noise with nothing connected to the antenna jack.
now de-tune L5 just a bit to quiet the noise down. you'll notice that it drops off pretty quickly.
now go back and re-test your S9 setting using your sig gen. you should not have lost more than about 1/2 an S-unit. if you did lose more than that, you might have to readjust L5 up a bit.
now just reset the S meter adjustment to S9.
yes, you have desensitized the radio a bit, but its really not noticeable in real world operation. usually atmospheric noise is stronger on an empty channel than any levels you'll be dealing with here.
LC
you will find many references to "white noise" when it comes to RCI/galaxy style radios. (remember when we used to just call them all 'exports'!?)
the problem with all of these references is that many of the threads will tell you to de-tune a certain coil to reduce the white noise, but since this is done in so many chassis with different part numbers, you can read the wrong thread and end up de-tuning the wrong coil in your radio.
for your 2970DX, the coil in question is L5. its the tuning can before the RF front end amp transistor.
after peaking the receive (using a SINAD meter! it's super important in these type radios) go back and unplug everything from the antenna socket on the radio.
set the radio volume to allow you to easily hear all the noise with nothing connected to the antenna jack.
now de-tune L5 just a bit to quiet the noise down. you'll notice that it drops off pretty quickly.
now go back and re-test your S9 setting using your sig gen. you should not have lost more than about 1/2 an S-unit. if you did lose more than that, you might have to readjust L5 up a bit.
now just reset the S meter adjustment to S9.
yes, you have desensitized the radio a bit, but its really not noticeable in real world operation. usually atmospheric noise is stronger on an empty channel than any levels you'll be dealing with here.
LC
