On Apr 7, 9:41 pm, james wrote:
On Fri, 6 Apr 2007 20:10:23 -0400, "Radiosrfun"



wrote:
+++"james" wrote in message
m...
+++ On Thu, 05 Apr 2007 19:57:47 +0200, Giulia
+++ wrote:
+++
++++++Hi ,
++++++i have a problem with a president jackson cb ,
++++++in tx there is about 100hz noise (i tx with car battery no PSU),
++++++the noise there is even if carrier is unmodulted (fm and am mode)....
++++++Can someone halp me ?
++++++Schemtics are aviable and i can use an oscilloscope.........
++++++
++++++Giulia
+++ *************
+++
+++ 100Hz?????
+++
+++ That is a subaudible frequency.
+++ How could anyone detect it without a scope?
+++
+++ james
+++
+++The range of "normal" human hearing is 20-20,000 Hz. How is 100 Hz
+++"subaudible"?
+++

****************

That maybe true but the Human ear does not perceive sounds with a flat
response for that frequency range. Instead as frequency goes very low
and also very high the power density for a given frequency may have to
increase or decrease. The human ear does not have a flat range of
sensitivity.

and this has nothing to do with the guys problem with his radio.

Also in communications the Human voice has very little power below
300Hz. Therefore most communications equiptment considered below 300
Hz as subaudible. A well designed receiver for voice communications
should reject frequencies below 300Hz. In fact they should also reject
frequencies above about 3KHz also.

and this still has nothing to do with his problem. The radio is
malfunctioning.



The range of 300 to 3000 Hz is where the ear is most sensitive to
frequencies. Also the Human voice contains most of its power between
this range.

james
more nonsense, the radio is not functioning correctly. you spouted out
some statement that was incorrect and instead of just saying you made
an error. or that you misunderstood you posted this useless garbage.
if you get a 60HZ hum coming from a bad transformer in a power supply
you don't need a scope to detect it. and I certainly have never had
any troubles hearing one before.