More info: FM Interference when the sun comes up
 

"Colin" wrote in message ...
From Canada, when trying to tune in a weak signal from the USA to get
National Public Radio I find that at night and on cloudy days the signal
is
clear and fine. I am using a Showgun TV antenna and amplifying it through
a
Trisonic 10db 10-900 MHz box.

On bright sunny days, at about 10 am when the sun is rising higher in the
sky the signal gets
gradually worse until there is so much interference that the signal is as
good as lost. In the evening it comes back and is clear again. It appears
to
affect only weak stations, the local stronger stations have no
interference.

Can anyone tell me what may be triggering this noise? Is there anything I
can do about it?

Thanks

Thank you for the feedback on this issue. Here are some more discoveries:

The power supply for this radio is a 175 watt inverter powered from a 12
volt battery, which in turn is charged by a set of solar panels, the charge
from which is regulated by a Morningstar Sunsaver charge controller. If I
unplug the radio from the inverter and plug into the regular power supply
from the grid, the noisy signal becomes clear. Additionally, after I unplug
from the inverter, for a second or so as the fields in the system die down
the signal becomes clear before the radio stops working.

This seems to indicate that the antenna is ok, and that the interference is
in the solar system somewhere, but not the inverter (otherwise the night
time reception would be bad) but perhaps the charge controller is having an
effect on the Trisonic amplifier?

Colin wrote:

The power supply for this radio is a 175 watt inverter powered from a 12
volt battery, which in turn is charged by a set of solar panels, the charge
from which is regulated by a Morningstar Sunsaver charge controller. If I
unplug the radio from the inverter and plug into the regular power supply
from the grid, the noisy signal becomes clear. Additionally, after I unplug
from the inverter, for a second or so as the fields in the system die down
the signal becomes clear before the radio stops working.

This seems to indicate that the antenna is ok, and that the interference is
in the solar system somewhere, but not the inverter (otherwise the night
time reception would be bad) but perhaps the charge controller is having an
effect on the Trisonic amplifier?

I'm guessing that the inverter or charge controller are throwing out RF noise
that's interfering. Since it's "heliotropic," maybe the latter. Have you
tried unplugging the solar cell from the charge controller during the day and
seeing if it clears up? If not, give it a go and see what you learn...

"Colin" wrote in message ...

Thanks for the thoughts, Eric - I did as you suggest, there was no
difference. As noted, if I switch to grid power the interference is gone.
However the solar array is still sending a charge to the controller at
this
point, so if it was simply RF noise from something in the 'solar chain'
the
noise should persist even when plugged into the grid.

Not necessarily. The current flowing from solar cell to controller is
likely to be nearly zero when not feeding the radio. You won't be
interrupting much current in that case, and would generate little if any
noise.

I'm suspecting
something about the link between the inverter and the radio power supply.

Have you done any common-mode filtering of the leads from the inverter and
the radio? I have an inverter - claimed to be very radio-quiet - that makes
a mess of the FM band. I never bothered to try filtering since I seldom use
the setup. It was powering a laptop computer, but once the battery charged,
I could run for 2 or 3 hours without the inverter.

The radio is an ancient Sony from 1975. Yes, it is time I replaced the
radio...

Why? I don't see that as being part of your problem.

"R J Carpenter" wrote in message
...

"Colin" wrote in message ...

Thanks for the thoughts, Eric - I did as you suggest, there was no
difference. As noted, if I switch to grid power the interference is
gone.
However the solar array is still sending a charge to the controller at
this
point, so if it was simply RF noise from something in the 'solar chain'
the
noise should persist even when plugged into the grid.

Not necessarily. The current flowing from solar cell to controller is
likely to be nearly zero when not feeding the radio. You won't be
interrupting much current in that case, and would generate little if any
noise.

I see your point. I will try to relate the noise to the state of charge of
the battery. I would think that if the state of charge is low then the array
will be firing all kinds of current at the battery through the controller
even if the radio is not trying to draw it down.


I'm suspecting
something about the link between the inverter and the radio power
supply.

Have you done any common-mode filtering of the leads from the inverter and
the radio? I have an inverter - claimed to be very radio-quiet - that
makes
a mess of the FM band. I never bothered to try filtering since I seldom
use
the setup. It was powering a laptop computer, but once the battery
charged,
I could run for 2 or 3 hours without the inverter.

I will investigate this as well, thanks.