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-   -   want circuit/schematic for CB "jammer" (https://www.radiobanter.com/homebrew/21141-re-want-circuit-schematic-cb-%22jammer%22.html)

Troglodite September 5th 03 07:41 PM


One of my neighbors uses rather 'salty' language and the local kids use some
walkie talkies around the house - I fugured that jamming the outside signals
would still allow the kids to talk due to their close proximity.


Get FRS radios for the kids. They are cheap, reliable, and will NOT receive
standard CB transmissions.


Troglodite September 5th 03 07:41 PM


One of my neighbors uses rather 'salty' language and the local kids use some
walkie talkies around the house - I fugured that jamming the outside signals
would still allow the kids to talk due to their close proximity.


Get FRS radios for the kids. They are cheap, reliable, and will NOT receive
standard CB transmissions.


Limitedselection September 5th 03 07:54 PM

From: "Caveat Lector"

Further should you radiate a very low level signal -- when the 29MHz band
has good nproagation -- you will send even a low level milliwatt signal for
hundreds of miles via "skywave" (skip if you will)


Caveat Lector,

Someone else posted about skywave - I was unaware.

I wouldn't be worried about thelegal issues if skywave was not an issue. But
unfortunately it looks like with skywave any signal no matter how small can be
heard world-wide.

Thanks.


Limitedselection September 5th 03 07:54 PM

From: "Caveat Lector"

Further should you radiate a very low level signal -- when the 29MHz band
has good nproagation -- you will send even a low level milliwatt signal for
hundreds of miles via "skywave" (skip if you will)


Caveat Lector,

Someone else posted about skywave - I was unaware.

I wouldn't be worried about thelegal issues if skywave was not an issue. But
unfortunately it looks like with skywave any signal no matter how small can be
heard world-wide.

Thanks.


Roy Lewallen September 5th 03 09:16 PM

Hm, that is an interesting problem. The trick would be to have a signal
that's always considerably stronger at the walkie-talkies than the
CBer's, regardless of where they might be in the house or on the
property, but always considerably weaker than the signal from the other
walkie-talkie. That won't be easy, if it's possible at all. Your best
shot would be to use another walkie-talkie, because it would be directly
radiating on the right frequency. It'd also be legal, for what that's
worth to you. You'd need to reduce its signal output by shielding,
cutting down the antenna, reducing the battery voltage, or some other
means like stringing ferrite cores over the antenna. But I wouldn't bet
on its accomplishing what you're trying to do, unless the CB
interference is pretty weak. Reducing the walkie-talkie receiver
sensitivity is another option, if the receiver is separately accessible
internally and you know enough about such things to do it. But I think
the best idea, suggested by another poster, is to contact the FCC. The
law can, occasionally, be used to your advantage.

Roy Lewallen, W7EL

Limitedselection wrote:
Roy,
Thanks - Mike posted about sky waves (I was unaware of), so even a very low
power device centrally located in my property would apparently be heard
world-wide - which is NOT what I want.

Actually, I did want to jam the reception of the existing CB signals on my
property (at least in and around the house).

One of my neighbors uses rather 'salty' language and the local kids use some
walkie talkies around the house - I fugured that jamming the outside signals
would still allow the kids to talk due to their close proximity.

Thanks again.


From: Roy Lewallen



There's no way to make a signal stop at your property line, short of
putting a perfect shield around your property. And if you did that, you
wouldn't be bothered by your neighbor's CB anyway.






Roy Lewallen September 5th 03 09:16 PM

Hm, that is an interesting problem. The trick would be to have a signal
that's always considerably stronger at the walkie-talkies than the
CBer's, regardless of where they might be in the house or on the
property, but always considerably weaker than the signal from the other
walkie-talkie. That won't be easy, if it's possible at all. Your best
shot would be to use another walkie-talkie, because it would be directly
radiating on the right frequency. It'd also be legal, for what that's
worth to you. You'd need to reduce its signal output by shielding,
cutting down the antenna, reducing the battery voltage, or some other
means like stringing ferrite cores over the antenna. But I wouldn't bet
on its accomplishing what you're trying to do, unless the CB
interference is pretty weak. Reducing the walkie-talkie receiver
sensitivity is another option, if the receiver is separately accessible
internally and you know enough about such things to do it. But I think
the best idea, suggested by another poster, is to contact the FCC. The
law can, occasionally, be used to your advantage.

Roy Lewallen, W7EL

Limitedselection wrote:
Roy,
Thanks - Mike posted about sky waves (I was unaware of), so even a very low
power device centrally located in my property would apparently be heard
world-wide - which is NOT what I want.

Actually, I did want to jam the reception of the existing CB signals on my
property (at least in and around the house).

One of my neighbors uses rather 'salty' language and the local kids use some
walkie talkies around the house - I fugured that jamming the outside signals
would still allow the kids to talk due to their close proximity.

Thanks again.


From: Roy Lewallen



There's no way to make a signal stop at your property line, short of
putting a perfect shield around your property. And if you did that, you
wouldn't be bothered by your neighbor's CB anyway.






Bob Lewis \(AA4PB\) September 5th 03 09:18 PM

I do NOT want to interfere with any reception (other than my own).

How about just turning your CB receiver off?



Bob Lewis \(AA4PB\) September 5th 03 09:18 PM

I do NOT want to interfere with any reception (other than my own).

How about just turning your CB receiver off?



Limitedselection September 5th 03 09:50 PM

From: Roy Lewallen


Hm, that is an interesting problem. The trick would be to have a signal
that's always considerably stronger at the walkie-talkies than the
CBer's, regardless of where they might be in the house or on the
property, but always considerably weaker than the signal from the other
walkie-talkie.


Roy,
Originally I was thinking build a small low-power jamming device and locate it
in the center of the house. Then the field area being jammed would hopefully
surround the house - but not extend out too far. Being as it was located
inside I was assuming that the signal would not be as strong as the walkie to
walkie signals outside.

Someone else suggested jamming the tranmitter's receiver (I like that idea!).
They were talking about using a mobile with a car battery and a magnet antenna
inside a garbage bag. Any CB jamming device schematics around (I would hate to
lose a real radio).

Someone suggested via email that if the walkie talkies were crystal rather than
PLL you could swap the two crystals and the radio would be below channel 1 on a
'funny' channel. I tried swapping crystals on one and it was definately on a
different channel - I then swapped them in another one and the two could talk
again - but I couldn't hear them on one I hadn't swapped the crystals on. I
found them on my shortwave receiver down below channel 1. This may work out.

The FCC was not interested in the situation. It might be different if a bunch
of people complained about the same person, I don't know - but apparently one
person complaining means very little to them.

So far the crystal swapping may be the best way out - they get to keep the CB
walkie talkies which are better than the FRS radios I have (range/reception) -
but it is very quiet on the new channel!

I would still be interested in any schematics for jamming circuits though.

Thanks again.


Limitedselection September 5th 03 09:50 PM

From: Roy Lewallen


Hm, that is an interesting problem. The trick would be to have a signal
that's always considerably stronger at the walkie-talkies than the
CBer's, regardless of where they might be in the house or on the
property, but always considerably weaker than the signal from the other
walkie-talkie.


Roy,
Originally I was thinking build a small low-power jamming device and locate it
in the center of the house. Then the field area being jammed would hopefully
surround the house - but not extend out too far. Being as it was located
inside I was assuming that the signal would not be as strong as the walkie to
walkie signals outside.

Someone else suggested jamming the tranmitter's receiver (I like that idea!).
They were talking about using a mobile with a car battery and a magnet antenna
inside a garbage bag. Any CB jamming device schematics around (I would hate to
lose a real radio).

Someone suggested via email that if the walkie talkies were crystal rather than
PLL you could swap the two crystals and the radio would be below channel 1 on a
'funny' channel. I tried swapping crystals on one and it was definately on a
different channel - I then swapped them in another one and the two could talk
again - but I couldn't hear them on one I hadn't swapped the crystals on. I
found them on my shortwave receiver down below channel 1. This may work out.

The FCC was not interested in the situation. It might be different if a bunch
of people complained about the same person, I don't know - but apparently one
person complaining means very little to them.

So far the crystal swapping may be the best way out - they get to keep the CB
walkie talkies which are better than the FRS radios I have (range/reception) -
but it is very quiet on the new channel!

I would still be interested in any schematics for jamming circuits though.

Thanks again.



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