Which omnidirectional base antenna will put out the least TV
and telephone interference in the neighborhood?

"Glenn S." wrote in message
...

Which omnidirectional base antenna will put out the least TV
and telephone interference in the neighborhood?

It doesn't depend on the antenna almost at all. The main cause of
interference is from three sources. One a dirty transmitter, the second is
from receiver front end over load, and the third is from RF getting in to
the electronics directly.

The first one you can do something about by using a clean transmitter. In
other words one that hasn't been messed around with such as peaking etc.
Peaking a CB radio requires messing around with the tuned output circuits
which are responsible for presenting the proper load to the output
transistor. These circuits are also responsible for filtering out the
harmonic signals that cause interference to TV signals. The people who peak
radios rarely if ever check the radio output for spectral purity and the now
peaked radio may have a much dirtier output that it had before it was
touched.

Receiver front end over load you can do little to prevent except by keeping
your antenna as far away from your neighbor's TV/radio antenna as you can
get.

As far as RF getting in to the electronics directly you can suggest they try
using some RFI suppression chokes they can buy at the local Radio Shack.
Other than that the fault lies with the manufacture of the malfunctioning
electronic device.

The use of a amplifier is not recommended since one it isn't legal to use on
the CB band, and second it makes all of the above problems much worse.

As long as you operate using legal and unmodified equipment you will be in
the clear even if one or more of your neighbors complains to the FCC. The
was a case here in the Detroit area 3 to 4 years ago where a local CBer was
coming in over his neighbor's TV's, radios and cordless phones. The FCC
investigated his station and found everything in order, no illegal or
modified equipment. The FCC told the city there was nothing they could do
since his station meet all FCC specifications and suggested the people
having problems either complain to the manufacture of the affected device,
or buy some RFI suppression devices and try them out.

--
Leland C. Scott
KC8LDO

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On Mon, 20 Sep 2004 00:33:28 -0400, "Leland C. Scott"
wrote:


"Glenn S." wrote in message
.. .

Which omnidirectional base antenna will put out the least TV
and telephone interference in the neighborhood?

It doesn't depend on the antenna almost at all. The main cause of
interference is from three sources. One a dirty transmitter, the second is
from receiver front end over load, and the third is from RF getting in to
the electronics directly.

That's not entirely true. The antenna DOES have a part to play in the
whole mess. Some of the "stick"-type antennas, such as the A-99, have
poor decoupling and this allows for significant coaxial shield
radiation. Some of these antennas also concentrate a good portion of
their near field radiation in places where it would exacerbate front
end overload or couple R.F. into house wiring.

An otherwise clean transmitter coupled to an antenna with the above
characteristics can cross the line between no RFI and significant RFI.
In some cases, this can be mitigated somewhat by moving the antenna
(usually raising it) to another area, where it's radiation will not
couple as much R.F. into neighboring premises. A better solution would
be to run an antenna with ground plane radials, such as a Sigma 5/8
wave or similar.

Dave
"Sandbagger"
http://home.ptd.net/~n3cvj

An otherwise clean transmitter coupled to an antenna with the above
characteristics can cross the line between no RFI and significant RFI.
In some cases, this can be mitigated somewhat by moving the antenna
(usually raising it) to another area, where it's radiation will not
couple as much R.F. into neighboring premises. A better solution would
be to run an antenna with ground plane radials, such as a Sigma 5/8 wave
or similar.
Dave
"Sandbagger"
http://home.ptd.net/~n3cvj
_
And the running of certain amplifiers will NOT compound or add
additional RFI in such cases. A perfect linear for cbers is a palomar,
as it is not class C, which certain long-time hammie posters in
rec.radio.cb consider to be some kind of devil-spawned conspiratorial
gadget to reek havoc and cause misery in their radio lives.

(Twistedhed) wrote in message ...
An otherwise clean transmitter coupled to an antenna with the above
characteristics can cross the line between no RFI and significant RFI.
In some cases, this can be mitigated somewhat by moving the antenna
(usually raising it) to another area, where it's radiation will not
couple as much R.F. into neighboring premises. A better solution would
be to run an antenna with ground plane radials, such as a Sigma 5/8 wave
or similar.
Dave
"Sandbagger"
http://home.ptd.net/~n3cvj
_
And the running of certain amplifiers will NOT compound or add
additional RFI in such cases. A perfect linear for cbers is a palomar,

there you go again encouraging lawbreaking

as it is not class C, which certain long-time hammie posters in
rec.radio.cb consider to be some kind of devil-spawned conspiratorial
gadget to reek havoc and cause misery in their radio lives.

LOL its 'wreak' havoc not reek, journalism boy

"I Am Not George" wrote in message
m...
(Twistedhed) wrote in message
...
An otherwise clean transmitter coupled to an antenna with the above
characteristics can cross the line between no RFI and significant RFI.
In some cases, this can be mitigated somewhat by moving the antenna
(usually raising it) to another area, where it's radiation will not
couple as much R.F. into neighboring premises. A better solution would
be to run an antenna with ground plane radials, such as a Sigma 5/8 wave
or similar.
Dave
"Sandbagger"
http://home.ptd.net/~n3cvj
_
And the running of certain amplifiers will NOT compound or add
additional RFI in such cases. A perfect linear for cbers is a palomar,

there you go again encouraging lawbreaking

as it is not class C, which certain long-time hammie posters in
rec.radio.cb consider to be some kind of devil-spawned conspiratorial
gadget to reek havoc and cause misery in their radio lives.

LOL its 'wreak' havoc not reek, journalism boy

Are you sure?

"I ain't George either" wrote:
"I Am Not George" wrote in message
om...
(Twistedhed) wrote in message
...
An otherwise clean transmitter coupled to an antenna with the
above
characteristics can cross the line between no RFI and significant
RFI.
In some cases, this can be mitigated somewhat by moving the
antenna
(usually raising it) to another area, where it's radiation will
not
couple as much R.F. into neighboring premises. A better solution
would
be to run an antenna with ground plane radials, such as a Sigma
5/8 wave
or similar.
Dave
"Sandbagger"
http://home.ptd.net/~n3cvj
_
And the running of certain amplifiers will NOT compound or add
additional RFI in such cases. A perfect linear for cbers is a
palomar,

there you go again encouraging lawbreaking

as it is not class C, which certain long-time hammie posters in
rec.radio.cb consider to be some kind of devil-spawned
conspiratorial
gadget to reek havoc and cause misery in their radio lives.

LOL its 'wreak' havoc not reek, journalism boy

Are you sure?


"WREAK" *

Definition: * [v] *cause to happen or to occur as a consequence;
"wreak havoc"

"REEK"

Definition: *

[n] *a distinctive odor that is offensively unpleasant
[v] *have an element suggestive (of something); "Twisty saying he is a
journalist reeks of untruth, especially since he doesn't know the
difference between "reek" and "wreak"."

WA3MOJ wrote:
LOL its 'wreak' havoc not reek, journalism boy
_
Oh ye who live in glass houses,,,,the term was used correctly in many of
my past posts,,,,lack of sleep, coming off the road after a long two
days straight driving and my return has you beside yourself seeking
typo/grammatical errors in my playground. You may now relax.

Steveo wrote:
(Twistedhed) wrote:
WA3MOJ wrote:
LOL its 'wreak' havoc not reek, journalism boy
_
Oh ye who live in glass houses,,,,the term was used correctly in
many
of
my past posts,,,,lack of sleep, coming off the road after a long
two
days straight driving and my return has you beside yourself seeking
typo/grammatical errors in my playground. You may now relax.

Hey Twist, that's N8WWM you're responding to.

hey steveo you assclown I am not N8wwm but thank God you are finally
believing me that I am not George lol

"Twistedhed" wrote in message
...
An otherwise clean transmitter coupled to an antenna with the above
characteristics can cross the line between no RFI and significant RFI.
In some cases, this can be mitigated somewhat by moving the antenna
(usually raising it) to another area, where it's radiation will not
couple as much R.F. into neighboring premises. A better solution would
be to run an antenna with ground plane radials, such as a Sigma 5/8 wave
or similar.
Dave
"Sandbagger"
http://home.ptd.net/~n3cvj
_
And the running of certain amplifiers will NOT compound or add
additional RFI in such cases. A perfect linear for cbers is a palomar,
as it is not class C, which certain long-time hammie posters in
rec.radio.cb consider to be some kind of devil-spawned conspiratorial
gadget to reek havoc and cause misery in their radio lives.

Twist the amp doesn't have to be class "C" to cause problems. Even a class
"B" linear amp is not completely clean. In particular solid state amps are a
problem because many are push-pull designs with no filtering on the output.
A push-pull design has low levels of even harmonic output since the even
order signals cancel out in the output transformer. And that is only for
"well matched" power transistors. The problem with the push-pull design is
the odd order harmonics are not attenuated at all! If you care to look at
Ham rigs that use wide band solid state push-pull amplifier output for HF
operation you will see band pass filters on the output. In fact these
filters are switched in and out depending on the band in use. That's how the
manufactures keep the output clean enough to meet FCC specifications.

Tube amplifiers are another story. These amplifiers can be relativity clean
IF the output is designed correctly. The critical section is the output
matching circuit. This circuit performs two important functions; load
matching and harmonic filtering. Some of the posters on this board in the
past don't seem to grasp these two ideas well. They seem to think that if
the amp loads up OK then all is well - not true. If you go through the math
you will discover that there is no unique solution for the value of the
matching section component values. So how do the designers pick the values
they do? They pick an operation "Q" for the matching section, that forces a
particular value for the components. The significance of the "Q" value is it
is a measure of how frequency selective the matching section becomes. The
higher the "Q" the sharper the response becomes, thus the less harmonic
energy is coupled to the output. Pick a "Q" too low and you have significant
harmonic output from the amplifier. Pick a value too high makes the
amplifier a pain to use, in other words the amplifier has to be retuned for
small shifts in operating frequency. From either experience, or through
detailed and complex calculations, acceptable values for "Q" have been
determined that would yield a tube amplifier matching circuit that is likely
to have acceptably low levels of harmonic output content.

If somebody says their amp is "clean" well the only sure way to know is to
test it with a spectrum analyzer. If you look at reviews for Ham rigs, and
power amplifiers in particular, you will see spectrum analyzer screen shots
so the buyers can see for themselves just how clean the output happens to
be. And I haven't seen a spectrum analyzer screen shot for a 11m solid state
amplifier yet. If you know of any it would be interesting to see them.


--
Leland C. Scott
KC8LDO

Wireless Network
Mobile computing
on the go brought
to you by Micro$oft