If that RV had a solar panel on top, that could also be the source of the noise. Solar charge controllers are kinda like a variable switching power supply. Mine? causes interference all the way to 60 Mhz ! They are nasty. I would have thought that when the sun went down the noise would stop, but it doesn't change. I have to completely disconnect the controller to stop the noise.
Max
On Sunday, August 14, 2022, 03:04:00 AM CDT, Alan Cooper <cqw7aln@...> wrote:
my hope is that everyone is aware that there are active ham operational bands at 137khz and at 472khz - 479khz as well as comercial cw stations still using 500khz ?
I have often heard horrendous noise from RV users who have filthy spurs from their switcher power supplies/battery chargers from 100khz clear up through 14mhz!?!!
?but maybe i am the only one who has had these Reciever problems with "switcher" power supplies blanking out the radio.?
if I am out of line for mentioning these types of problems with switchers please ignore me...I am not wanting to cause trouble.
On Wed, Aug 10, 2022, 6:17 AM Ashhar Farhan <farhanbox@...> wrote:
Neils,
Many of these switching regulators have a 50 KHz switching frequency. This has images inside the passband of the audio codec.
I arrived at LM338 only after experimenting with various switching systems (including building one from discrete components). These new generation of switchers move the frequency to 500 KHz. That's what makes them useful.
- f
On Wed, Aug 10, 2022, 6:27 PM John Terrell <N6LN@...> wrote:
The smallest ones have a small cheap potentiometer which I would not trust in the long run to maintain a stable output voltage. Some have a secondary means of choosing between four or five fixed voltage levels and bypassing the fickle potentiometer by cutting a pcb trace with a hobby knife. Loupes help. But in any case a buffer capacitor ought to reduce a noisy output p.
