In addition to what CK said, if Ham radios had better filtering; then Hams wouldn't be complaining en masse about some CB operators 'spurious signals' getting into the Ham bands.
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CB Channel 6 Bleedover
- Thread starter Galaxy 959
- Start date
I have to disagree with this a little bit too. A lot of the times a CB is operated with a dirty amp or with the audio limiter disabled causing lots of IMD and no amount of receiver filtering will help when a spurious byproduct happens to fall within a receiver's passband. If a radio is producing a signal on 28.564 then no filter in the world will prevent it from being heard on 28.564.
As a side note to my other post above, upon second teading I wonder if KM3F was talking about frontend overload and not selectivity. A wide frontend could subject a receiver to out of band signals or even strong in band signals which may be strong enough to overload the RF preamp in the receivers first RF amp and cause issues that appear like extremely poor selectivity.Again however it is different than selectivity which can be enhanced by the use of narrower filters with steeper skirts.
Your amateur radio was several hundred to several thousand dollars, not a hundred bucks. For a hundred bucks you don't get good IF filter skirts. In fact for several hundred bucks you don't get much narrower than 15kHz and you're typically looking at 20kHz spacing to see 90dB or so of selectivity without optional filters.
You can't filter out harmonics. If you're on 28.300 and the unsuppressed harmonic of a transmitter at a lower frequency is at is 28.300 then you're going to hear it. Thats why 40m transmitters have bandpass filtering because if they don't then the poor buggers on 15m get to hear everything they're TXing.
CB's Gone Wild
In the case of CB radios,if they were properly tuned for a minimum spurious signal generation and the modulation not allowed above 100%(90% ideal IMO),we'd all be sitting happy eating creme pie.
Maybe the FCC is going after the worst offenders on 11 meters. I don't think an overly amount of CB operators will take the time to contact the FCC about a bleed over /co-channel issue. A lot of CB operators have lost their privilege to transmit on their CB radios because they're out of spec. Not to mention all the 10 meter export converted radios they run on 11 meters.
Would the FCC ever be funded to reign in the 11 meter band? Only if it interferes with HF emergency backup systems police,fire,and rescue may have now or in the future. The present administration has begun pushing again towards that utopian pipe dream. Will that include spectrum enforcement ?
P.S. I'd be interested in a narrower filter but only if I have the ability to tune the other guy in or just get a FT-897D
P.S. Here's some literature.
http://rf.harris.com/media/Radio Comms in the Digital Age - 1_tcm26-12947.pdf
In the case of CB radios,if they were properly tuned for a minimum spurious signal generation and the modulation not allowed above 100%(90% ideal IMO),we'd all be sitting happy eating creme pie.
Maybe the FCC is going after the worst offenders on 11 meters. I don't think an overly amount of CB operators will take the time to contact the FCC about a bleed over /co-channel issue. A lot of CB operators have lost their privilege to transmit on their CB radios because they're out of spec. Not to mention all the 10 meter export converted radios they run on 11 meters.
Would the FCC ever be funded to reign in the 11 meter band? Only if it interferes with HF emergency backup systems police,fire,and rescue may have now or in the future. The present administration has begun pushing again towards that utopian pipe dream. Will that include spectrum enforcement ?
P.S. I'd be interested in a narrower filter but only if I have the ability to tune the other guy in or just get a FT-897D
P.S. Here's some literature.
http://rf.harris.com/media/Radio Comms in the Digital Age - 1_tcm26-12947.pdf
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The typical off the shelf CB radio or most so-called export radios including all the Ranger series use a Murata CFW455HT as the IF filter. This is the same as the CFW455H but with steeper skirts. Apparently the "T" stands for "Tight". Attenuation is -50dB at +/- 9 KHz. Sure not thegreatest however I contend it is better than most CB bashers want to admit. I myself have no horse in this race as I am not and have not been on 11m in over 25 years however I have worked on some and stick by my assertion that the bandwidths, while not great, are not as bad as some would have people believe.
Robb was talking about a CB signal getting into an amateur band not harmonics. He never said anything about harmonics at all. Harmonics are not the reason a 27 MHz signal interferes on the 28-29.7 MHz band.
Hello again
The subject always produces a lot of different interpatation's of what was being referred to.
The attempt was to make the case for poor CB receiver design overall {and} the dirty signals they have to contend with.
Some designs are better than other but at the price/quality level they won't be on par with amateur equipment, level for level.
.
On TX, again overdriven radios stock or modified in this market produce a pile of dirty output. [a huge technical subject] by it'self
Feed a amplifier of usual poor design that pile of dirt and you get a mountain of dirt out the other end. [a huge technical subject again]
The technical reasons for all of it fills a book.
How any CB ops understand any of it, not many.
Those who (insist on doing it are ignorant and many do not care..
As for Ham radio we have the same overall technical issues but on a more limited basis, overall.
Is the equipment better, yes it is but sill cannot separate all undesirable signals despite all the filtering available in the better units.
Here are several examples;
VHF/UHF operation. Distance about 3 miles. Power 1500 watts.
This op swamps me line of sight on nearly any part of the band with splatter.. Can it be helped. NO it has to be accepted, as he is doing nothing 'much' wrong. It's a case of overload and overdrive, internal RX IMD and who know what else. This op is hitting the audio and amplifier pretty hard but only during contest time so it's not worth generating hard feeling over a temporary set of conditions..
.
Next example KW TS 2000 radio.
De-sense from adjacent signals at 5 kHz up or down.
Is it a fault? Maybe yes maybe no. Depends on how you look at it.
This radio has hi and low cut DSP.
Hi cut goes out to 5 kHz. Set there causes de sense from the strong adjacent signal power. It's inherent to the design
Hi cut set back to 2800 or lower stops the de-sense.
Question is is it a fault, a design issue or to be expected with a wide setting?
Depends on how you look at the issue for this particular design which is admittedly somewhat old now as compared to recent day new advanced designs.
For specific example I can cut down a signal as close as 1500 hz if not to much over S9. So the old design still works pretty good.
Then you have beat cancel and notch control to add where it will be effective.
On AM operation most radios are broad in the RX department but can be narrowed by using certain ticks available depending on design of the radio, to clean up QRM from up or down a crowded band.
.
Bottom line is the difference between the two radio services, how they are used, the operating integrity level in each, and the equipment quality.
In amateur service we are allowed 1500 watts peak, have access to more than 15 bands and for the most part it works ok for most everyone as opposed to CB where there is 1 band, equipment is low quality, misused and ops have little knowledge of what there creating with misused and illegal equipment, and cannot be told on top if all of it.
There really is no argument when one looks at the basic uses and differences.
And one wonders why there is splatter over a wide frequency range one or more states away from an illegal operation. That's pretty bad for many reasons!
Good luck..
The subject always produces a lot of different interpatation's of what was being referred to.
The attempt was to make the case for poor CB receiver design overall {and} the dirty signals they have to contend with.
Some designs are better than other but at the price/quality level they won't be on par with amateur equipment, level for level.
.
On TX, again overdriven radios stock or modified in this market produce a pile of dirty output. [a huge technical subject] by it'self
Feed a amplifier of usual poor design that pile of dirt and you get a mountain of dirt out the other end. [a huge technical subject again]
The technical reasons for all of it fills a book.
How any CB ops understand any of it, not many.
Those who (insist on doing it are ignorant and many do not care..
As for Ham radio we have the same overall technical issues but on a more limited basis, overall.
Is the equipment better, yes it is but sill cannot separate all undesirable signals despite all the filtering available in the better units.
Here are several examples;
VHF/UHF operation. Distance about 3 miles. Power 1500 watts.
This op swamps me line of sight on nearly any part of the band with splatter.. Can it be helped. NO it has to be accepted, as he is doing nothing 'much' wrong. It's a case of overload and overdrive, internal RX IMD and who know what else. This op is hitting the audio and amplifier pretty hard but only during contest time so it's not worth generating hard feeling over a temporary set of conditions..
.
Next example KW TS 2000 radio.
De-sense from adjacent signals at 5 kHz up or down.
Is it a fault? Maybe yes maybe no. Depends on how you look at it.
This radio has hi and low cut DSP.
Hi cut goes out to 5 kHz. Set there causes de sense from the strong adjacent signal power. It's inherent to the design
Hi cut set back to 2800 or lower stops the de-sense.
Question is is it a fault, a design issue or to be expected with a wide setting?
Depends on how you look at the issue for this particular design which is admittedly somewhat old now as compared to recent day new advanced designs.
For specific example I can cut down a signal as close as 1500 hz if not to much over S9. So the old design still works pretty good.
Then you have beat cancel and notch control to add where it will be effective.
On AM operation most radios are broad in the RX department but can be narrowed by using certain ticks available depending on design of the radio, to clean up QRM from up or down a crowded band.
.
Bottom line is the difference between the two radio services, how they are used, the operating integrity level in each, and the equipment quality.
In amateur service we are allowed 1500 watts peak, have access to more than 15 bands and for the most part it works ok for most everyone as opposed to CB where there is 1 band, equipment is low quality, misused and ops have little knowledge of what there creating with misused and illegal equipment, and cannot be told on top if all of it.
There really is no argument when one looks at the basic uses and differences.
And one wonders why there is splatter over a wide frequency range one or more states away from an illegal operation. That's pretty bad for many reasons!
Good luck..
Its not just you they bleed on everyone and they are running upwards of 60,000 w or more
they call it the supper bowl and it is very annoying in georgia also as all my naybors and people they talk to have the same isue ........
It getts to the point to where sometimes cant even talk local with a 1000w ....
some people have shortcommings and they make up for it with a broadcast 60,000w amp....
They are also doing the same thing on ch 28 Motor mouth maul.....
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I kinda like the KFC mashed potato bowl, although I'm not much on the whole fast food thing.Its not just you they bleed on everyone and they are running upwards of 60,000 w or more
they call it the supper bowl and it is very annoying in georgia also as all my naybors and people they talk to have the same isue ........
It getts to the point to where sometimes cant even talk local with a 1000w ....
some people have shortcommings and they make up for it with a broadcast 60,000w amp....
They are also doing the same thing on ch 28 Motor mouth maul.....
BTW, is 1,000 watts more or less legal than 60,000 watts?
Well,I've begun to have an understanding about filtering myself thanks to all the info that's available and to you guys on this forum who take time to explain things. There are many on the CB band who are totally ignorant about radios and radio wave propagation and there's those of us who are learning about the hobby.
Those that splatter usually care about nothing else than making the next DX contact. Then there's others that have fairly clean loud audio who are living for that next DX contact but still co-channel others. It's a dog eat dog world in CB land if you're doing DX.
Most if the time when my home channel gets too crazy with DX I'll just go up on 10 meters and listen to something more sane.
Those that splatter usually care about nothing else than making the next DX contact. Then there's others that have fairly clean loud audio who are living for that next DX contact but still co-channel others. It's a dog eat dog world in CB land if you're doing DX.
Most if the time when my home channel gets too crazy with DX I'll just go up on 10 meters and listen to something more sane.
Its not just you they bleed on everyone and they are running upwards of 60,000 w or more
they call it the supper bowl and it is very annoying in georgia also as all my naybors and people they talk to have the same isue ........
It getts to the point to where sometimes cant even talk local with a 1000w ....
some people have shortcommings and they make up for it with a broadcast 60,000w amp....
They are also doing the same thing on ch 28 Motor mouth maul.....
Yea I hear west coast motor mouth all the time on 28. Is that like some kinda station or something in a tower. Sounds like a commercial.
He's an individual and Fireball's arch nemesis Amtennas and Coax
He's running a 12 element circular polarization beam antenna 35 high.
He's running a 12 element circular polarization beam antenna 35 high.
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