Source of 150kHz spur?

[Dummy]

When I was testing the transmit power of a radio,
a spur with Fc-150kHz was observed in spectrum analyzer. It appears
across the frequency band 403MHz to 470MHz while transmitting.
Spurs amplitude was about -70dBm, might be significant enough to cause
interference to adjacent channel frequencies.
Could the 150kHz be the harmonics of clock freq or something else...

 

[Mac]

On Mon, 13 Dec 2004 21:56:09 -0800, Dummy wrote:

When I was testing the transmit power of a radio,
a spur with Fc-150kHz was observed in spectrum analyzer. It appears
across the frequency band 403MHz to 470MHz while transmitting.
Spurs amplitude was about -70dBm, might be significant enough to cause
interference to adjacent channel frequencies.
Could the 150kHz be the harmonics of clock freq or something else...

Switching power supply?

--Mac

 

[Tam/WB2TT]

"Dummy" <ahkit1021@yahoo.com> wrote in message
news:74bb84c0.0412132156.5f89589@posting.google.com...

When I was testing the transmit power of a radio,
a spur with Fc-150kHz was observed in spectrum analyzer. It appears
across the frequency band 403MHz to 470MHz while transmitting.
Spurs amplitude was about -70dBm, might be significant enough to cause
interference to adjacent channel frequencies.
Could the 150kHz be the harmonics of clock freq or something else...

Check the FCC spec, but I think -70 db is OK. The fact thay you are getting
f -150, and not f +/- 150 would indicate that it is a mixer product
somewhere. I would start looking back from the output stage until you find
it.

Tam

 

[Lawrence Oravetz]

Mac brought next idea :

On Mon, 13 Dec 2004 21:56:09 -0800, Dummy wrote:

When I was testing the transmit power of a radio,
a spur with Fc-150kHz was observed in spectrum analyzer. It appears
across the frequency band 403MHz to 470MHz while transmitting.
Spurs amplitude was about -70dBm, might be significant enough to cause
interference to adjacent channel frequencies.
Could the 150kHz be the harmonics of clock freq or something else...


Switching power supply?

--Mac

might be a harmonic of the Lo in the radio... Could be a wireless
microphone too.

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