Five Basic Steps to Better Shortwave Radio Listening [SWL]
 

On 01/18/2011 10:10 PM, Bob Dobbs wrote:

The TV antenna was useful to get OTA LA stations like KCAL9,
SoCal's premier car chase station.g

KCAL is where KCBS puts all their ghetto stuff.

Five Basic Steps to Better Shortwave Radio Listening [SWL]
 

On 01/19/2011 12:10 AM, wrote:


Oh,that's why some people started using alumium siding ! It is almost
a Faraday cage...

Around here all the houses are stucco, with steel lath. Nothing
penetrates below about 400 MHz, when the windows start admitting
electrical fields.

Five Basic Steps to Better Shortwave Radio Listening [SWL]
 

On Jan 19, 12:10*am, wrote:
On Jan 19, 1:10*am, Bob Dobbs wrote:



D. Peter Maus wrote:

* You sound like you're living in the noise equivalent of the Little
Big Horn.

Before the last move three years ago I lived close to there.
Or so it seemedhttp://img.myph.us/Ar9.jpg
From the left is a Butternut 80/40 vertical then an Imax 2000 (CB antenna)
for 10, 12, 15 and also mounted on the back porch a Diamond V2000 for
6, 2, 440. then on the roof is a discone plus some UHF WX transponders.
In addition to Cox and Ma Bell were 4kv, 12kv distribution feeders,
and above that a 138kv tie line (not visible in pic). All of that wire either
radiated its own noise or parasitically re-radiated noise of the others
so it was often, but not always, difficult to get a precise source to use in the
phase noise canceler (ANC-4).
The TV antenna was useful to get OTA LA stations like KCAL9,
SoCal's premier car chase station. g

- Oh,that's why some people started using alumium
- siding ! It is almost a Faraday cage...

A Faraday Cage {Copper Kettle} works both ways.

Five Basic Steps to Better Shortwave Radio Listening [SWL]
 

On Jan 18, 2:05*pm, bpnjensen wrote:
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...ongwire%20Balu...

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?

The 'concept' is that the Feed-in-Line "Inline Isolator"
[1:1 Transformer] is in the Radio Shack -or- at the point
the Feed-in-Line enters the House/Building.

Mount the "Inline Isolator" directly on a Ground Rod
right outside the Radio Shack Window.
http://www.wellbrook.uk.com/longwire.html

Placement at this point prevents the AC Line Noise
and other RFI Noises in the House from 'migrating' out
along the Coax to the Antenna|End; and then ?reflecting?
back from the Antenna along the Coax back into the
Radio Shack and into the Radio/Receiver.

iane ~ RHF

Common mode noise reduction/elimination.
 

On 1/16/2011 11:24 AM, bpnjensen wrote:
Question to those who may have used one - Do inline isolators work
well on RX? Such as those sold by Radioworks?

Thanks,
Bruce Jensen


It sounds like, if you use an outdoor antenna, you need a 9:1 balun/unun
(depending on antenna design/length) at the point where the feed line
feeds the antenna, with the shield grounded at this point to a good
earth ground.

Next, a 1:1 unun (50 to 50, or 75 to 75, ohm) between the coax and the
receiver, with a good earth ground on the receiver.

This should remove any common mode noise on the shield of the coax.
This is what I use ...

If you use a balanced antenna, you need a balun at the feedline where it
feeds the antenna, if you use a longwire/unbalanced-antenna, you need a
unun at this point.

Regards,
JS

Five Basic Steps to Better Shortwave Radio Listening [SWL]
 

On 01/19/2011 12:46 PM, D. Peter Maus wrote:


But mix products are difficult to track down, let alone eliminate.
You'll need to find, and isolate the point at which rectification is
taking place, and that could be ANYWHERE...wherever metal components in
any structure touch, you can get rectification, which will product mix
products from the environmental RF. It took me a couple of years to
finally track down and eliminate the mix products being generated on my
property. Padding down the antenna input also helped.

You really ARE in the Little Big Horn for noise and interference.


A 20 dB pad will help the swamping. Have you tried an MFJ-956 preselector?

Clamp On RF Choke Stops Noise on AC Mains
 

On 01/20/2011 03:40 AM, RHF wrote:

hope this helps - iane ~ RHF
.
.
You need mix #43 for HF

Five Basic Steps to Better Shortwave Radio Listening [SWL]
 

On Jan 20, 10:08*am, dxAce wrote:
bpnjensen wrote:
On Jan 19, 2:24 pm, dave wrote:
On 01/19/2011 12:46 PM, D. Peter Maus wrote:

But mix products are difficult to track down, let alone eliminate.
You'll need to find, and isolate the point at which rectification is
taking place, and that could be ANYWHERE...wherever metal components in
any structure touch, you can get rectification, which will product mix
products from the environmental RF. It took me a couple of years to
finally track down and eliminate the mix products being generated on my
property. Padding down the antenna input also helped.

You really ARE in the Little Big Horn for noise and interference.

A 20 dB pad will help the swamping. Have you tried an MFJ-956 preselector?

Not yet, but I've been thinking about a preselector. *Does the MFJ
work well?

Save your money until you find out definitively whether your RFI is actually
coming in internally or externally, and if it is external, the ONLY way to
resolve that issue is trying to get something done with your local power
provider.

Elsewise... flee- Hide quoted text -

- Show quoted text -

I don't disagree - but it may be that the only way to determine
whether the problem is internal vs. external is by spending at least a
few $$. I can do this.

Inline Isolators for RFI reduction ?
 

On Jan 16, 11:24*am, bpnjensen wrote:
Question to those who may have used one - Do inline isolators work
well on RX? *Such as those sold by Radioworks?

Thanks,
Bruce Jensen

I do wish to say at this point that I greatly appreciate the interest
and information on this thread. I feel like I may be able to make some
headway, even if toward nothing else than a better understanding of
the local problems. Thanks to everyone...

BJ

Inline Isolators for RFI reduction ?
 

On 1/20/2011 3:59 PM, bpnjensen wrote:
On Jan 16, 11:24 am, wrote:
Question to those who may have used one - Do inline isolators work
well on RX? Such as those sold by Radioworks?

Thanks,
Bruce Jensen

I do wish to say at this point that I greatly appreciate the interest
and information on this thread. I feel like I may be able to make some
headway, even if toward nothing else than a better understanding of
the local problems. Thanks to everyone...

BJ

Are they current ununs or voltage ununs?

Current "baluns" should be fine ...

Regards,
JS