On 7/26/2014 10:02 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lr0908$usv$1@dont-
email.me:

If the box is putting out that much interference, there's a good chance
it has a problem (and may be operating illegally). I would think
correcting the problem at the source would be the better option.


Nope. It's one of those consumer widgets, one o millions, that have a
disclaimer saying that some limited interference must be accepted. Knowing
this, it isn't even worth trying to police the issue, and probably impossible
anyway. Computer based stuff just does this to us, there's no stuffing THAT
genie back in the bottle now.


That does not mean it's not operating illegally. Even with such a tag,
it can be emitting a signal illegally.

ALL potential sources of RF have limits on their emissions. Exceed
those limits and they are not operating legally. It may be due to
shoddy workmanship or a problem with the device itself.

--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

On Sat, 26 Jul 2014 09:02:44 -0500, Lostgallifreyan
wrote:

Nope. It's one of those consumer widgets, one o millions, that have a
disclaimer saying that some limited interference must be accepted. Knowing
this, it isn't even worth trying to police the issue, and probably impossible
anyway. Computer based stuff just does this to us, there's no stuffing THAT
genie back in the bottle now.

Much depends on the device causing the problem. It's often cheaper
and easier to just buy the owner a new device instead of trying to fix
it. I've done that a few times with Chinese junk that never had a
prayer of meeting FCC Part 15 incidental radiation limits. So far,
I've replaced one ethernet switch, one 4 line phone, and 2 security
cameras in the neighborhood. Also, a mess of junk switcher type cell
phone chargers.

However, you can't do that if you don't know what's causing the noise.
So, take your portable radio, wrap it in aluminum foil to REDUCE the
sensitivity, and snoop around the building until you find the culprit.
The rest you can figure out yourself. Hint: Diplomacy works.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/26/2014 12:32 AM, Jeff Liebermann wrote:
On Fri, 25 Jul 2014 14:21:07 -0500, Lostgallifreyan
wrote:

I hope to boost the incoming signal to override the ocal RF mush from nearby
flats, and to do this for a portable receiver so I want no cables attached to
it at all. I have considered two possible ideas:

Hey Jeff,
Is it possible to build a tuned loop connected to the backside of the
radio, to cover the FM band. I never tried a loop at 100Mhz.
Mikek



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On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote:
Hey Jeff,
Is it possible to build a tuned loop connected to the backside of the
radio, to cover the FM band. I never tried a loop at 100Mhz.
Mikek

Sure. Google for VHF magnetic loop antenna.
https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch
They work so-so, but have the same problem as the HF version. The Q
is very high resulting in extremely narrow usable bandwidth. In order
to make it work, there would need to be some way of tuning the loop to
frequency. Making it track the receiver frequency would be a big
plus.

http://www.m0ukd.com/wordpress/homebrew/magnetic-loop-antennas/
He forgot to insert a series tuning cap in the gamma match, but
otherwise, it should give you an idea of what's involved.

http://www.iw5edi.com/technical-articles/144-mhz-magnetic-loop-antenna
Much better.

Anyway, recalculate for 100 MHz and it should work.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/26/2014 10:15 AM, Jeff Liebermann wrote:
On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote:
Hey Jeff,
Is it possible to build a tuned loop connected to the backside of the
radio, to cover the FM band. I never tried a loop at 100Mhz.
Mikek

Sure. Google for VHF magnetic loop antenna.
https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch
They work so-so, but have the same problem as the HF version. The Q
is very high resulting in extremely narrow usable bandwidth. In order
to make it work, there would need to be some way of tuning the loop to
frequency. Making it track the receiver frequency would be a big
plus.

I expected to have a tuning cap on the loop to tune to his frequency
of interest. I don't know about polarization, but he may be able to
rotate out some interference with a loop.


Mikek


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amdx wrote in :

I expected to have a tuning cap on the loop to tune to his frequency
of interest. I don't know about polarization, but he may be able to
rotate out some interference with a loop.


Slightly cubersome for my situaion but technically true, so a nice idea.
Thanks.

On 7/26/2014 10:57 AM, amdx wrote:
On 7/26/2014 10:15 AM, Jeff Liebermann wrote:
On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote:
Hey Jeff,
Is it possible to build a tuned loop connected to the backside of the
radio, to cover the FM band. I never tried a loop at 100Mhz.
Mikek

Sure. Google for VHF magnetic loop antenna.
https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch
They work so-so, but have the same problem as the HF version. The Q
is very high resulting in extremely narrow usable bandwidth. In order
to make it work, there would need to be some way of tuning the loop to
frequency. Making it track the receiver frequency would be a big
plus.

I expected to have a tuning cap on the loop to tune to his frequency
of interest. I don't know about polarization, but he may be able to
rotate out some interference with a loop.


Mikek


I've* calculated a 6 inch loop made with a #12 or #14 wire will
resonate the FM band with a cap between 6.5pf and 10pf. Roughly!
Now, I'll see if I can generate the gumption in the next couple
of days to build it to see if it has any positive effect.
I hope someone beats me to it.
With an AM loop and radio the signal couples to the internal loop very
well, I don't know how well you can couple a signal into an FM radio.
Mikek

* actually I used a couple of online calculators.

http://www.deephaven.co.uk/lc.html

http://www.daycounter.com/Calculator...lculator.phtml

On Fri, 25 Jul 2014 14:21:07 -0500, Lostgallifreyan wrote:

I hope to boost the incoming signal to override the ocal RF mush from nearby
flats ...

It might be wiser to see if you can identify the source(s) of the offending
"mush" instead. You would be doing yourself and others a service by doing so.
Contact your local authority and see if they will look into it. Can't hurt to
try, and the rewards may be worth it.