Indoor FM boost with no cables?
 

On 7/30/2014 9:40 AM, Jerry Stuckle wrote:
On 7/30/2014 1:22 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lr9ohj$33f$1@dont-
email.me:

But the amplifier you're trying to use is meant to feed a receiver
directly, not another antenna. So output is going to be very low (on
the order of microwatts) - much lower than any amplifier which feeds an
antenna.


Small point, but.... Microwatts. Those new legal microstransmitters are said
to be in NANOwatt range output, but allegedly work on the distance scales I'm
interested in. Microwatts should certainly have worked, but despite the crude
test dipole being good (on standard wired reception test anyway), it didn't
work for transmitting even a foot or two with the radio's whip parallel to
the upper part of it. If nanowatts should have, the MAR-6 looks like driving
picowatts, if I'm lucky. :)


I would suggest you check again. Receivers aren't that sensitive. Most
unlicensed transmitters are in the 100-500 mw range, and have a coverage
of maybe 100 feet. And picowatts aren't even worth discussing.

I'm unclear, is mW microwatts or milliwatts as you wrote it? The reason
I ask is that a 500 milliwatt transmitter would certainly have a
receivable distance much greater than 100 feet, no?

--

Rick

Indoor FM boost with no cables?
 

On 7/31/2014 9:28 PM, Jeff Liebermann wrote:
On Thu, 31 Jul 2014 20:24:10 -0400, Jerry Stuckle
wrote:

Yes, I know the story, Jeff. That's why I quoted it. And it's not the
only business which has had problems with GE ballasts. GE has claimed
they've fixed the problem with additional filtering. We'll see.

Here's more on the story on noisy GE electronic ballasts:
http://www.commlawblog.com/2014/02/articles/enforcement-activities-fines-f/bulbs-behind-bars-iii-more-lighting-fixtures-mess-up-mobile-data-service/
However, GE has found that a small number of units of the
2-lamp ballasts identified above that were manufactured
prior to September 19, 2011 have produced unintentional
high-frequency radio emissions that have the potential to
cause interference with certain types of wireless communications.

...the product codes for the problem ballasts were 72262 and 72266.

Note that the bulletin was NOT publicly distributed by GE and that
there was no voluntary recall by GE. Looks like GE has effectively
buried the problem. With only two documented interference complaints,
both with clueless business owners, I don't believe that the FCC has
enough cause to act on the matter. However, I will give GE credit for
somewhat publicly admitting that there was a problem, even if they did
bury it.






Yes, Jeff, I am quite aware of the entire story. There is a lot more
about it than you have found. I just didn't post it here because it is
unrelated to the newsgroup. However, there have been several articles
about it in the technical newsletters.

--
==================
Remove the "x" from my email address
Jerry, AI0K

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

Indoor FM boost with no cables?
 

On 7/31/2014 9:29 PM, rickman wrote:
On 7/30/2014 9:40 AM, Jerry Stuckle wrote:
On 7/30/2014 1:22 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lr9ohj$33f$1@dont-
email.me:

But the amplifier you're trying to use is meant to feed a receiver
directly, not another antenna. So output is going to be very low (on
the order of microwatts) - much lower than any amplifier which feeds an
antenna.


Small point, but.... Microwatts. Those new legal microstransmitters
are said
to be in NANOwatt range output, but allegedly work on the distance
scales I'm
interested in. Microwatts should certainly have worked, but despite
the crude
test dipole being good (on standard wired reception test anyway), it
didn't
work for transmitting even a foot or two with the radio's whip
parallel to
the upper part of it. If nanowatts should have, the MAR-6 looks like
driving
picowatts, if I'm lucky. :)


I would suggest you check again. Receivers aren't that sensitive. Most
unlicensed transmitters are in the 100-500 mw range, and have a coverage
of maybe 100 feet. And picowatts aren't even worth discussing.

I'm unclear, is mW microwatts or milliwatts as you wrote it? The reason
I ask is that a 500 milliwatt transmitter would certainly have a
receivable distance much greater than 100 feet, no?


According to standards, mW is milliwatts. uW (actually, greek "mu"W but
I'm not using a charset here that defines it, so the standard is "uW")
would be microwatts.

--
==================
Remove the "x" from my email address
Jerry, AI0K

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

Indoor FM boost with no cables?
 

On Thu, 31 Jul 2014 20:34:32 -0400, Jerry Stuckle
wrote:

Could be - but what was radar doing at 200Mhz? Not only will it
interfere with both business band and amateur frequencies, but the large
beam width would make it pretty useless. And as weather radar, it would
be useless.

Left over from the cold war. Someone forgot to turn it off or
something.

214-236 Mhz. Not sure about the pulse repetition frequency but it had
to be fairly low audio frequency in order to obtain the long range. At
3500ft elevation, the radar range is 84 miles.

Some of the URL's below show 420 to 450 MHz for the AN/FPS-24. That's
wrong for the early models. Built in 1957 and pulled the plug in
1980:
http://en.wikipedia.org/wiki/Mount_Umunhum
http://en.wikipedia.org/wiki/AN/FPS-24
http://www.radomes.org/museum/equip/fps-35.html
https://www.google.com/search?q=mt+umunhum+radar&tbm=isch
https://www.youtube.com/watch?v=nqfsWBZR8XM
I can see the building through the trees from my house. Amazing what
5 megawatts can do.

The dish rotated at the then standard rate of two revolutions per
minute. So, every 30 seconds, there was a blast of buzz from the
hi-fi, 2way, phone, and oven (I didn't have a TV back then). I
learned to automatically stop talking just before the bzzzzzt, and
continue talking after it was gone in about one second. When they
pulled the plug in 1980, I continued to do this unconsciously for
several months. Incidentally, I tried bypasses and ferrite beads.
They helped, but didn't totally eliminate the buzz. Transcribing
vinyl records to 1/4" tape was a lost cause.



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

Indoor FM boost with no cables?
 

On Thu, 31 Jul 2014 20:37:16 -0400, Jerry Stuckle
wrote:

I should also add - "ran a 2way shop for about 11 years".

You really shouldn't truncate my quotes. What I said was
"I did RF design and ran a 2way shop for about 11 years."
That means that I bounced back and forth between RF design and 2way
radio for about 11 years with a few gaps in between. The elapsed time
was from 1971 through about 1983.

Somewhat after graduating college, I worked for Communitronix
repairing CB and commerical radios (mostly CB) and installing radios
in cement mixers. I vaguely recall that the owner fired me, probably
for good reason.

I then went to work for Pacific Mobile Communications in Stanton CA,
which still exists today. Mostly, it was maintaining three repeater
sites in the L.A. area.
http://802.11junk.com/jeffl/pics/Old%20Repeaters/index.html
The building to the right was the main site on Santiago Pk:
http://www.trabucooutdoors.com/assets/images-1/odds_ends/santiagopk.jpg

PMC is associated with Alpha Electronics, which made sub-audible tone
boards for various radios, DC and tone remotes, etc. The later tone
boards used hybrids. We had our own hybrid production line, PCB
etching facility, assembly line, and production test. When not
dealing with the radios, I helped design all of these.

After that, was hired by Standard Communication (SCC) of Wilmington to
integrate various products, mostly from Alpha Electronics, into their
product line. I didn't stay long, mostly because of the 1.5 hr
commute.

Somewhat later, I left the area and eventually landed in the Santa
Clara area, where I worked for Intech Inc designing mostly marine
radios. Finding photos is a bit difficult, but I did manage to find
one of the Intech M3600 2-30 MHz HF SSB marine radio:
http://www.hellocq.net/forum/read.php?tid=226493
Offhand, I recall doing about 12 products in 9.5 years. Numbers and
details if you want them. Oh, some manuals here for the AN-SRD/21 and
AN-SRD/22 direction finders for the USCG.
http://802.11junk.com/jeffl/AN-SRD-21/
http://802.11junk.com/jeffl/AN-SRD-22/

After Intech, I went to work for Granger Assoc where I designed a
900MHz SCADA system to be used by Southern Calif Edison for remote
power factor capacitor switching. I did the transmitter, power amp,
RF switching, duplexer, and whatever nobody else wanted to do.

I left Granger in about 1983 to become a real estate speculator,
consultant, and student. I decided to turn my hobby into a profession
and become a computer consultant. I attached myself to computer store
and built up the repair business, while maintaining my RF consulting
business.

Since most of my experience since that time has been in on radio
related areas, I won't bother to detail them. There were also some
short term jobs and contracts mixed in with the aforementioned work
that are not worth mentioning.

That hardly
qualifies you as an "expert".

I do not claim to be an expert. What I said was
"I guess that having more years of experience entitles
me to tell you how to run your life."
You indicated that on the same basis, you could tell
Mr Lostgallifreyan to:
"I suggest you not try to teach those who know
more than you your "facts".
I would appreciate it if you would extend me the same courtesy and not
try to teach me your "facts".

As for "RF design" - what did you design
- TV amplifiers?

See detail above. List of products and responsibility if you want
them. I'll have to do some digging to find them all, but am willing
if you think it will help you in some way.



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

Indoor FM boost with no cables?
 

On Thu, 31 Jul 2014 21:29:11 -0400, rickman wrote:

I would suggest you check again. Receivers aren't that sensitive. Most
unlicensed transmitters are in the 100-500 mw range, and have a coverage
of maybe 100 feet. And picowatts aren't even worth discussing.

I'm unclear, is mW microwatts or milliwatts as you wrote it? The reason
I ask is that a 500 milliwatt transmitter would certainly have a
receivable distance much greater than 100 feet, no?

He's right. The receivers aren't that sensitive. For example, I just
excavated the Silicon Labs Si470-31 data sheet, which shows an FM
sensitivity of 1.1 uV into 50 ohms for a S+N/N ratio of 26dB. The
reason is the wide (200KHz for FM and 500KHz HD Radio) occupied
bandwidths. The bigger the bandwidth, the more noise gets in, and the
lower the sensitivity. Crudely, double the bandwidth and lose -3dB
(i.e. half) in sensitivity.

Much depends on the antennas and the field strength sensitivity. Let's
see what the Friis Equations produces. If I assume a best case of a
2dB gain dipole at the transmitter, but a crude earphone cord antenna
at the receiver (-3dB at best). Then what I get is:
TX 27dBm (500 mw)
TX ant 2dB
path loss ????
RX ant -3dB
RX sens -107dBm
Path Loss = 27 + 2 -3 -107 = 81 dB
Plugging into:
http://www.proxim.com/products/knowledge-center/calculations/calculations-free-space-loss
I get 1.7 miles at 100 MHz. Looks like it should work.

Things get messy when I run the numbers again with the typical
receiver sensitivity found in analog receivers. These have typical
sensitivity of 9 dBf. That's dB(Femtowatts) or 10^-15 watts
reference. Converting to a milliwatts reference, that's:
9*10^-15 watts / 1*10^-3 watts = 9*10^-12
converting to dB, or 10 log of the ratio:
dB = 10*log(9*10^-12) = 10 * (-11) = -110 dBm
which is allegedly 3dB more sensitive than the all digital chip. I
don't believe it. So, with 3dB less sensitivity, you should get about
half the range or 0.85 miles.




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

Indoor FM boost with no cables?
 

On 7/31/2014 9:47 PM, Jerry Stuckle wrote:
On 7/31/2014 9:29 PM, rickman wrote:
On 7/30/2014 9:40 AM, Jerry Stuckle wrote:
On 7/30/2014 1:22 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lr9ohj$33f$1@dont-
email.me:

But the amplifier you're trying to use is meant to feed a receiver
directly, not another antenna. So output is going to be very low (on
the order of microwatts) - much lower than any amplifier which feeds an
antenna.


Small point, but.... Microwatts. Those new legal microstransmitters
are said
to be in NANOwatt range output, but allegedly work on the distance
scales I'm
interested in. Microwatts should certainly have worked, but despite
the crude
test dipole being good (on standard wired reception test anyway), it
didn't
work for transmitting even a foot or two with the radio's whip
parallel to
the upper part of it. If nanowatts should have, the MAR-6 looks like
driving
picowatts, if I'm lucky. :)


I would suggest you check again. Receivers aren't that sensitive. Most
unlicensed transmitters are in the 100-500 mw range, and have a coverage
of maybe 100 feet. And picowatts aren't even worth discussing.

I'm unclear, is mW microwatts or milliwatts as you wrote it? The reason
I ask is that a 500 milliwatt transmitter would certainly have a
receivable distance much greater than 100 feet, no?


According to standards, mW is milliwatts. uW (actually, greek "mu"W but
I'm not using a charset here that defines it, so the standard is "uW")
would be microwatts.

I'm not asking about the standard, I'm asking what you meant by mW. Why
do you say with a power level of 500 mW (27 dBm) a transmitter would
only have a range of 100 feet? With the low bandwidth we are discussing
this seems to be *very* short.

--

Rick

Indoor FM boost with no cables?
 

"Lostgallifreyan" wrote in message
. ..

Michael Black wrote in
news:alpine.LNX.2.02.1407260017460.20123@darkstar. example.org:

Modify the radio so coax can be attached, and feed it from the good
antenna outside (or even just positioned well inside).

Or, buy a radio that already has an external antenna jack.


Now that would be cheating. :) Actually the one I bought does have one, but
the point was convenience, allowing local tuning as usual but with no
unwanted wires trailing around as I carry a radio between rooms while
working.

If it were practical I imagine we'd all be doing it, I just wondered if
there
might be soem compromise I can use, but likely not one that isn't already
standard practise.

If you will be changing to a different station more often than every hour or
two, stop reading now. I cannot help you.

You can buy a low-power FM broadcaster for considerably less than US$100,
according to a few quick checks I made online just now. If you have any
location in your flat where you get reliable reception of your favorite
station(s), locate a receiver there and connect the audio out -- headphone
jack or speaker terminals -- into the FM broadcaster and choose an unused
frequency on the FM radio spectrum for the FM broadcaster. Then, listen to
that frequency. Your source for audio could be almost any device with an
AUDIO OUT jack: AM radio, FM radio, CD player, computer audio (for streaming
services).

I know it works reliably. Before I retired, my desk in a metal building was
far from the nearest window and AM radio listening was almost impossible,
with squeals and squawks from the computers. I used an FM broadcaster to
send the audio of my favorite station across the room from a location by a
window to an FM radio on my desk. I powered the AM radio and the FM
broadcaster from two wall transformers. It literally worked for years, as I
never turned it off.

Power consumption is insignificant. More details on request.

"Sal"
KD6VKW

Indoor FM boost with no cables?
 

"Jeff Liebermann" wrote in message
...

On Thu, 31 Jul 2014 21:29:11 -0400, rickman wrote:

I would suggest you check again. Receivers aren't that sensitive. Most
unlicensed transmitters are in the 100-500 mw range, and have a coverage
of maybe 100 feet. And picowatts aren't even worth discussing.

I'm unclear, is mW microwatts or milliwatts as you wrote it? The reason
I ask is that a 500 milliwatt transmitter would certainly have a
receivable distance much greater than 100 feet, no?

He's right. The receivers aren't that sensitive. For example, I just
excavated the Silicon Labs Si470-31 data sheet, which shows an FM
sensitivity of 1.1 uV into 50 ohms for a S+N/N ratio of 26dB. The
reason is the wide (200KHz for FM and 500KHz HD Radio) occupied
bandwidths. The bigger the bandwidth, the more noise gets in, and the
lower the sensitivity. Crudely, double the bandwidth and lose -3dB
(i.e. half) in sensitivity.

Much depends on the antennas and the field strength sensitivity. Let's
see what the Friis Equations produces. If I assume a best case of a
2dB gain dipole at the transmitter, but a crude earphone cord antenna
at the receiver (-3dB at best). Then what I get is:
TX 27dBm (500 mw)
TX ant 2dB
path loss ????
RX ant -3dB
RX sens -107dBm
Path Loss = 27 + 2 -3 -107 = 81 dB
Plugging into:
http://www.proxim.com/products/knowledge-center/calculations/calculations-free-space-loss
I get 1.7 miles at 100 MHz. Looks like it should work.

Things get messy when I run the numbers again with the typical
receiver sensitivity found in analog receivers. These have typical
sensitivity of 9 dBf. That's dB(Femtowatts) or 10^-15 watts
reference. Converting to a milliwatts reference, that's:
9*10^-15 watts / 1*10^-3 watts = 9*10^-12
converting to dB, or 10 log of the ratio:
dB = 10*log(9*10^-12) = 10 * (-11) = -110 dBm
which is allegedly 3dB more sensitive than the all digital chip. I
don't believe it. So, with 3dB less sensitivity, you should get about
half the range or 0.85 miles.
================================================== =====

When I was in the Navy, I was detached from my ship for a short school. I
bought a Radio Shack FM broadcaster that used a 9v battery. A couple of
guys and I fashioned a folded dipole for the FM band as the transmit antenna
and used a BCB radio for the audio input. We pushed the folded dipole a few
feet out a second-story window on a broom handle and proceeded across the
base to see how far we could hear our signal on a portable FM radio.

We went about a 1000 feet before the signal became useless, although there
were some dropouts closer than that. I do not know the output of the device
in milliWatts, but I suspect it is much less than the nominal 100 milliWatts
that limits the no-license operation.

"Sal"

Indoor FM boost with no cables?
 

"Sal M. O'Nella" wrote in message ...



major snipping

less than the nominal 100 milliWatts
that limits the no-license operation.
================================================== ====

I don't think that 100 milliWatt limit exists now, if it ever did. The FCC
provides guidance and the limit appears to be under a microWatt in the FM
band. I'd be happy to get clarification.

"Sal"