There Ought To Be A Law - Radio, Dirty Transmitter... commentary on spurious 75M TX emissions

Note: The interfering signal is on the right side of the screen ... 50 kHz up from where we are listening ...

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FCC Rules and Regulations, Part 97

http://www.arrl.org/FandES/field/regulations/news/part97/d-305.html#307

Applicable excerpt:

§97.307 Emission standards.

(a) No amateur station transmission shall occupy more bandwidth than necessary for the information rate and emission type being transmitted, in accordance with good amateur practice.

(b) Emissions resulting from modulation must be confined to the band or segment available to the control operator. Emissions outside the necessary bandwidth must not cause splatter or keyclick interference to operations on adjacent frequencies.

(c) All spurious emissions from a station transmitter must be reduced to the greatest extent practicable. If any spurious emission, including chassis or power line radiation, causes harmful interference to the reception of another radio station, the licensee of the interfering amateur station is required to take steps to eliminate the interference, in accordance with good engineering practice.

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See also the spectrum as displayed on Hewlett Packard (HP, now Agilent) model number 8591E spectrum analyzer:

http://www.youtube.com/watch?v=oH_yOrhGTS4

This video was taken 1-04-2009, almost a year after the op put this interfering transmitter on the air.

Spectrum Analyzer video from Feb. 2008: http://tinypic.com/player.php?v=4tknlx&s=3&hid=14&tag=meter

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Category:

Science & Technology

Tags:

• WW9W
• Splatter
• transmit spurious
• FCC Part 97
• Emission standards
• 3890
• Gates Splatter Master
• AM Operator

[uploadJ]

The interfering station is the one on the far right side of the screen (3890 kHz or so) operating in the AM mode from a modified AM Broadcast Band (a BC-1G, originally 535-1605 kHz) transmitter modified for the 75 Meter (3890 kHz) ham band operation.

The interfering spurious signal coming out of the BC-1G transmitter is affecting 'traffic' over 50 kHz down the band ...

[disgruntldtoad]

There is nothing I despise more than chatting with someone and having another station start splattering all over us from 5 or even 10 Kc's down.

[uploadJ]

This particular case is, well, just a little bit more severe; 'splatter' (actually, a spurious signal from the transmitter on voice peaks due to some internal feedback and oscillation) tears things up 50 kHz (and further) up and down the band.

I continue to let the guy know he's tearing things up, but, well, some heads can be harder than others!

Thanks for the comment.

[F41Driver]

I listen to this group of guys sometimes, lol.

[alanspicertelecom]

It's been amazing me ... recently ... how a ham station transmitting a LSB signal could be tearing up a station UP in frequency ... Until you read a little on why this happens it doesn't make much sense. It sure makes me want to check my speech processor settings ... maybe even do some on-air testing to see if I can be heard up above where I am actually transmitting (by more than my allowed bandwidth.)

[Blaze1024]

Holly Cr@p! When I first looked at the scope I thought so what? Then I realized the bandwidth setting on the spectrum scope was set to +and - 50 Kilohertz !! This means the station on the right side of the scope was causing harmful interference to stations 50 Kc on either side of his center frequency. Which means this inconsiderate Lid was wiping out 100Kc 's of bandwidth on 80 meters . That's the equivalent of completely wiping out the whole 17 meter ham band Once Again Holly Cr@P !!