On 1/17/2011 1:36 PM, John Smith wrote:

...
ROFLOL ...

I thought it was bad when I seen those confused by the difference of rf
transformers to baluns/unun (TLTs) ... now we have a third term thrown
in that must mean "Isolation Transformer."

No wonder there is so much confusion out there ... so now we have rf
transformers, baluns, ununs, isolation transformers, transmission line
transformers and auto-transformers all being covered by the term "line
isolator."

It is going to fun watching two separate people talking about "line
isolators" ... ROFLOL

Regards,
JS

Oh yeah, and I forgot about "antenna traps", you can toss them in with
line isolators also ...

Regards,
JS

On 1/18/2011 6:56 AM, RHF wrote:

...
But it is 'by-design' a "Non-Resonate" Broadband
Shortwave Radio Listener's [SWL] Antenna using
a Broadbanded* 9:1 Matching Transformer. ~ RHF
* Frequency Range : 500kHz to 30 MHz
...

I don't know what antenna you are speaking of. But, the original bent
of this thread started out with "line isolators", actually traps meant
to resonate a single antenna on multiple bands ... usually a dipole,
however, can be used on monopoles also ...

Regards,
JS

On Jan 18, 9:02*am, John Smith wrote:
On 1/18/2011 6:56 AM, RHF wrote:

...
But it is 'by-design' a "Non-Resonate" Broadband
Shortwave Radio Listener's [SWL] Antenna using
a Broadbanded* *9:1 Matching Transformer. ~ RHF
* Frequency Range : 500kHz to 30 MHz
...

On 1/18/2011 11:44 AM, dave wrote:

...
No such thing. Those isolators just keep hum away. Hum is not your
problem. You are likely hearing triac noise (dimmer buzz, halogen
torchieres, waterbed heaters, etc.) over the air. It is coming in or
power lines and RF chokes on those lines will stop it at the electrical
box. But because you have overhead mains that probably won't help
enough. You may be able to reduce it enough to get better results from
your phase canceller. I'm peabrainstorming here...

What dave was attempting to describe is common mode noise. This is
probably at least a portion of your noise, best for you to decide:

http://www.w8ji.com/common-mode_noise.htm
http://www.dxengineering.com/TechArticles.asp?ID={3F341778-BFE9-4988-AD87-142FD1E04EB2}
http://www.yccc.org/Articles/W1HIS/C...S2006Apr06.pdf
http://www.hard-core-dx.com/nordicdx...ed/balun3.html

The links and scientific/technical papers on Common Mode Noise are
simply without end. Feel free to use a search engine and find material
which is easy for you to digest ...

Regards,
JS

On Jan 18, 10:57*am, John Smith wrote:
On 1/18/2011 10:44 AM, bpnjensen wrote:

...
Actually, no, and I am sorry if there was a misunderstanding - I meant
an inline (in the coax) RFI reduction system.

Baluns/ununs really are NOT an RFI reduction system. *They provide
proper impedance matching between antenna and feedline. *Coax, with an
rf choke (can be a balun/unun) allows the feedline to run though noisy
areas and not pick up the noise there, such as when it enters a house
with noise present.

Baluns/ununs/rf-transformers, because of the use in gaining a superior
match (transfer of signal energy) improves signal to noise ratio, in
most instances, and this can appear to be functioning as a "RFI
reduction system."

Some useful links:http://users.belgacom.net/hamradio/s...alun/balun.htm

Regards,
JS

OK, understood, but I have always thought (based on what I have read)
that one of these matching transformers, properly deisgned and
grounded, can bleed off some noise to ground. Am I misled?

On Jan 18, 11:44*am, dave wrote:
On 01/18/2011 10:44 AM, bpnjensen wrote:





On Jan 18, 9:02 am, John *wrote:
On 1/18/2011 6:56 AM, RHF wrote:

...
But it is 'by-design' a "Non-Resonate" Broadband
Shortwave Radio Listener's [SWL] Antenna using
a Broadbanded* *9:1 Matching Transformer. ~ RHF
* Frequency Range : 500kHz to 30 MHz
...

I don't know what antenna you are speaking of. *But, the original bent
of this thread started out with "line isolators", actually traps meant
to resonate a single antenna on multiple bands ... usually a dipole,
however, can be used on monopoles also ...

Regards,
JS

Actually, no, and I am sorry if there was a misunderstanding - I meant
an inline (in the coax) RFI reduction system.

No such thing. Those isolators just keep hum away. Hum is not your
problem. You are likely hearing triac noise (dimmer buzz, halogen
torchieres, waterbed heaters, etc.) over the air. It is coming in or
power lines and RF chokes on those lines will stop it at the electrical
box. *But because you have overhead mains that probably won't help
enough. You may be able to reduce it enough to get better results from
your phase canceller. I'm peabrainstorming here...- Hide quoted text -

- Show quoted text -

OK, good info. Do you think a magnetic loop could diminish reception
of the RFI from the overheads? Like, as Peter M. suggests, a
Wellbrook?

On 1/18/11 16:05 , bpnjensen wrote:
On Jan 18, 10:57 am, John wrote:
On 1/18/2011 10:44 AM, bpnjensen wrote:

...
Actually, no, and I am sorry if there was a misunderstanding - I meant
an inline (in the coax) RFI reduction system.

Baluns/ununs really are NOT an RFI reduction system. They provide
proper impedance matching between antenna and feedline. Coax, with an
rf choke (can be a balun/unun) allows the feedline to run though noisy
areas and not pick up the noise there, such as when it enters a house
with noise present.

Baluns/ununs/rf-transformers, because of the use in gaining a superior
match (transfer of signal energy) improves signal to noise ratio, in
most instances, and this can appear to be functioning as a "RFI
reduction system."

Some useful links:http://users.belgacom.net/hamradio/s...alun/balun.htm

Regards,
JS

OK, understood, but I have always thought (based on what I have read)
that one of these matching transformers, properly deisgned and
grounded, can bleed off some noise to ground. Am I misled?

Local environmental noise, and static, yes. Man made noise, or
noise radiated into the antenna space, not so much, no.

A properly designed matching transformer will improve the
transfer of antenna output to the receiver. And it will help drain
off static buildup on the antenna, and help reduce the noise floor.
But, if noise is being radiated into the air, as from powerlines,
digital toys, and dimmers and similar sources, and your antenna is
picking that up, it will depend on the antenna's ability to
discriminate between desired and undesired frequencies whether or
not you see a reduction in undesired signals.

It sounds as though much of your noise problem is related to your
connection to the mains. Mains borne noise is a big problem in radio
hobbycraft. Most of the noise in my own area is brought in through
the mains. The remainder is radiated from the hundreds of devices
throughout the neighborhood.

It's possible, though a PITA to do so, to bypass the mains with
safety caps between .1 - .01mfd (safety caps are essential, here,
for fire prevention) to reduce the irregular impulses on the line.
And isolation transformer, balanced to ground will also produce
significant results in reducing your noise, but that can be expensive.

Your least difficult path may be in isolating your radios from
the mains, entirely, and move to battery power.

On 1/18/2011 2:05 PM, bpnjensen wrote:

...
OK, understood, but I have always thought (based on what I have read)
that one of these matching transformers, properly deisgned and
grounded, can bleed off some noise to ground. Am I misled?

NO, you are not mislead. They are death on common mode noise. If your
problem is common mode noise they work like a miracle ... the signal to
noise boost the match ain't bad either ...

Regards,
JS

On 01/18/2011 02:07 PM, bpnjensen wrote:
On Jan 18, 11:44 am, wrote:
On 01/18/2011 10:44 AM, bpnjensen wrote:





On Jan 18, 9:02 am, John wrote:
On 1/18/2011 6:56 AM, RHF wrote:

...
But it is 'by-design' a "Non-Resonate" Broadband
Shortwave Radio Listener's [SWL] Antenna using
a Broadbanded* 9:1 Matching Transformer. ~ RHF
* Frequency Range : 500kHz to 30 MHz
...

I don't know what antenna you are speaking of. But, the original bent
of this thread started out with "line isolators", actually traps meant
to resonate a single antenna on multiple bands ... usually a dipole,
however, can be used on monopoles also ...

Regards,
JS

Actually, no, and I am sorry if there was a misunderstanding - I meant
an inline (in the coax) RFI reduction system.

No such thing. Those isolators just keep hum away. Hum is not your
problem. You are likely hearing triac noise (dimmer buzz, halogen
torchieres, waterbed heaters, etc.) over the air. It is coming in or
power lines and RF chokes on those lines will stop it at the electrical
box. But because you have overhead mains that probably won't help
enough. You may be able to reduce it enough to get better results from
your phase canceller. I'm peabrainstorming here...- Hide quoted text -

- Show quoted text -

OK, good info. Do you think a magnetic loop could diminish reception
of the RFI from the overheads? Like, as Peter M. suggests, a
Wellbrook?

I have heard amazing things. That model is pricey. You can build an
experimental loop for the price of a variable capacitor from MFJ and
some scrap coax.

On 01/18/2011 02:17 PM, D. Peter Maus wrote:
On 1/18/11 16:05 , bpnjensen wrote:
On Jan 18, 10:57 am, John wrote:
On 1/18/2011 10:44 AM, bpnjensen wrote:

...
Actually, no, and I am sorry if there was a misunderstanding - I meant
an inline (in the coax) RFI reduction system.

Baluns/ununs really are NOT an RFI reduction system. They provide
proper impedance matching between antenna and feedline. Coax, with an
rf choke (can be a balun/unun) allows the feedline to run though noisy
areas and not pick up the noise there, such as when it enters a house
with noise present.

Baluns/ununs/rf-transformers, because of the use in gaining a superior
match (transfer of signal energy) improves signal to noise ratio, in
most instances, and this can appear to be functioning as a "RFI
reduction system."

Some useful
links:http://users.belgacom.net/hamradio/s...alun/balun.htm


Regards,
JS

OK, understood, but I have always thought (based on what I have read)
that one of these matching transformers, properly deisgned and
grounded, can bleed off some noise to ground. Am I misled?

Local environmental noise, and static, yes. Man made noise, or noise
radiated into the antenna space, not so much, no.

A properly designed matching transformer will improve the transfer of
antenna output to the receiver. And it will help drain off static
buildup on the antenna, and help reduce the noise floor. But, if noise
is being radiated into the air, as from powerlines, digital toys, and
dimmers and similar sources, and your antenna is picking that up, it
will depend on the antenna's ability to discriminate between desired and
undesired frequencies whether or not you see a reduction in undesired
signals.

It sounds as though much of your noise problem is related to your
connection to the mains. Mains borne noise is a big problem in radio
hobbycraft. Most of the noise in my own area is brought in through the
mains. The remainder is radiated from the hundreds of devices throughout
the neighborhood.

It's possible, though a PITA to do so, to bypass the mains with safety
caps between .1 - .01mfd (safety caps are essential, here, for fire
prevention) to reduce the irregular impulses on the line. And isolation
transformer, balanced to ground will also produce significant results in
reducing your noise, but that can be expensive.

Your least difficult path may be in isolating your radios from the
mains, entirely, and move to battery power.


You need to embrace ferrites. They're like putting a low pass filter is
series with your mains. Shunt caps are scary. MOVs, sure.