[Lostgallifreyan]

Hello. I've seen many 'boosters' for radio reception, none of which do what
I'm hoping for, so either my aim is foolish beyond imagining, or really
interesting. Please tell me which.

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:
1. Take a feed from my existing outdoor antenna and make a dipole indoors,
for passive re-radiation of whatever the outdoor one picks up.
2. Same thing, but using a small preamp I built once (uses a MAR6 I think,
about 22dB gain), but instead of feeding the RF input on a tuner as usual,
drive a small dipole to allow any small receiver with a whip or a wire to get
enough of the externally derived signal to beat the indoor mush.

(I think that feedback would be a problem, with any serious power, but
perhaps something as small as the MAR6-based booster I mentioned might work
ok, given that the outdoor antenna is several tens of feet distant. Anyway,
that's the idea, and if it, or something I haven't thought of or mentioned at
all will solve this for me, please tell me. Alternatively, please tell me
what is the impossible obstacle to this notion...)

Crow.

[David Platt]

In article ,
Lostgallifreyan wrote:

Hello. I've seen many 'boosters' for radio reception, none of which do what
I'm hoping for, so either my aim is foolish beyond imagining, or really
interesting. Please tell me which.

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:

1. Take a feed from my existing outdoor antenna and make a dipole indoors,
for passive re-radiation of whatever the outdoor one picks up.

This might help a bit, depending on how good a signal your outdoor
antenna gets, and on proximity between your indoor antenna and the
portable receiver.

2. Same thing, but using a small preamp I built once (uses a MAR6 I think,
about 22dB gain), but instead of feeding the RF input on a tuner as usual,
drive a small dipole to allow any small receiver with a whip or a wire to get
enough of the externally derived signal to beat the indoor mush.

(I think that feedback would be a problem, with any serious power, but
perhaps something as small as the MAR6-based booster I mentioned might work
ok, given that the outdoor antenna is several tens of feet distant.

This *might* work, but as you note it has some problems. Feedback
could very well be an issue (and could be quite unpredictable as it
could change from day to day or minute to minute depending on the
presence or absence of signal-reflecting objects near the retransmit
antenna).

Also, it may not be strictly legal. Your "booster" would be, in
effect, a miniature broadcast station, (re)transmitting the whole
spectrum (not necessarily just the radio stations that you care
about).

A single-channel (re)transmitter might be legal here in the U.S. under
Part 15 regulations... but boosting and transmitting everything that
got into the outdoor antenna could really be problematic. You could
end up making reception worse for your flat-neighbors, if the system
you were boosting/repeating interfered with direct reception of the
same signal.

[Lostgallifreyan]

(David Platt) wrote in news:eiqaab-
:

A single-channel (re)transmitter might be legal here in the U.S. under
Part 15 regulations... but boosting and transmitting everything that
got into the outdoor antenna could really be problematic. You could
end up making reception worse for your flat-neighbors, if the system
you were boosting/repeating interfered with direct reception of the
same signal.



Yes, I have the same reservations about it. In the UK there are legal
small transmitters with range about 500 yards with clear line of sight, and I
was thinking I'd need a lot less capability and thus be safe but I don't know
what the safety margins for legality and polite usage would be, if any.

One thing I noticed tonight was that the transmitter signal strenth is
increased perhaps due to maintence work beign completed or halted for the
week end. There's not a lot of difference, but enough to indicate that just
6dB of boost might be plenty to solve this if it's safe to do it.

[Michael Black[_2_]]

On Fri, 25 Jul 2014, Lostgallifreyan wrote:

Hello. I've seen many 'boosters' for radio reception, none of which do what
I'm hoping for, so either my aim is foolish beyond imagining, or really
interesting. Please tell me which.

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:

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.

For FM, local interference should be less of a problem, since most of
it is AM. It would have to be quite strong to wipe out decent strength FM
signals. That said, what you need is to get stronger signals, so they
capture the limiters in the receiver.

Coincidentally, this week I came across a reprint of a great article from
Audio Magazine back in January 1991, where the author talks about getting
the dipole further up, and oriented properly, and then goes on to show a
collinear antenna made from 300ohm twinlead and some wire. A better
antenna is probably a good thing, and if it can be oriented to improve
wanted signals but not be so good for interfering signals, that's a good
thing. The article is he
http://home.earthlink.net/~schultdw/...Reception.html

But connecting directly to the radio is going to make the best
improvement. If you need the signal stronger than the local noise, any
amplification or remodulating transmitter will have to be stronger than
the local noise, and since radio signals drop off rapidly with distance,
a too strong for legal signals is likely to be needed.

Michael

[Jeff Liebermann[_2_]]

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:

I've actually done something like that for a customer, but first, I'll
take apart you two possible ideas;

1. Take a feed from my existing outdoor antenna and make a dipole indoors,
for passive re-radiation of whatever the outdoor one picks up.

Passive repeaters do not work well. I can go through the calculations
for you but basically, you get approximately twice the path loss with
a passive repeater, as you would with a direct path. I can grind the
numbers for you if you want later (I'm giving a talk tomorrow and need
to get some sleep).

2. Same thing, but using a small preamp I built once (uses a MAR6 I think,
about 22dB gain), but instead of feeding the RF input on a tuner as usual,
drive a small dipole to allow any small receiver with a whip or a wire to get
enough of the externally derived signal to beat the indoor mush.

What is there to keep the amplifier from amplifying the "mush"? If
you point your directional antenna in the wrong direction, you just as
easily be pointing it at the source of the noise. However, that's a
minor problem compared to multipath. You will still have some signal
arriving directly from the FM station, which will combine in some
random fashion with the amplified signal. If the phase difference
between the incident and amplified paths is 180 degrees, you'll have a
null and no signal. At 100 Mhz, 1/2 wave is about 1.5 meters, so
you'll have nulls every 1.5 meters inside your house.

(I think that feedback would be a problem, with any serious power, but
perhaps something as small as the MAR6-based booster I mentioned might work
ok, given that the outdoor antenna is several tens of feet distant.

Yes, it will be a problem. If you want to do that, read about how the
various cell phone bi-directional amplifiers prevent feedback.
(warning: It's messy).

Anyway,
that's the idea, and if it, or something I haven't thought of or mentioned at
all will solve this for me, please tell me. Alternatively, please tell me
what is the impossible obstacle to this notion...)

David Platt had the right idea. Build a repeater. You start with a
quality FM receiver that has a coax connector for the antenna.
Hopefully, it would get good reception and not pickup as much noise.
The audio output of the FM receiver would drive a Bluetooth wireless
speaker arrangement. Trade your portable receiver for a pair of BT
earphones or maybe a smartphone with BT. I suggest you go with the
newer BT 4.0 (BT Low Energy) instead of the older BT 3.0 (BT
standard). Range is about 10-30 meters, which should be adequate.
Something like this:
http://www.ebay.com/itm/311024899511
Search for: Bluetooth audio transmitter.

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

[Lostgallifreyan]

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.

[Lostgallifreyan]

Jeff Liebermann wrote in
:

Passive repeaters do not work well. I can go through the calculations
for you but basically, you get approximately twice the path loss with
a passive repeater, as you would with a direct path. I can grind the
numbers for you if you want later (I'm giving a talk tomorrow and need
to get some sleep).


No need, but thankyou. I read about them a bit. I get the idea that they're
huge, totally impractical as a spot fix for a few rooms in a basement flat.

What is there to keep the amplifier from amplifying the "mush"?

Plenty. The mush is very localised, some widget (likely a wireless net box
or router) in the upstairs flat, it is not detectable beyond a quarter of the
distance to my outside antenna. Hence, wondering if a tiny boost and an
indoor dipole might be enough to overcome the immediate locality without
annoying the neighbours. See, if that mush does not reach the outdoor antenna
in any measurable degree, it seemed to follow that a tiny boost to adequate
levels might also fail to reach that outdoor antenna, and thus feedback might
be avoided, as well as unwanted transmission strength beyond my boundaries.
Purely speculative, but it seems logical enough to me...

[Jerry Stuckle]

On 7/26/2014 6:15 AM, Lostgallifreyan wrote:
Jeff Liebermann wrote in
:

Passive repeaters do not work well. I can go through the calculations
for you but basically, you get approximately twice the path loss with
a passive repeater, as you would with a direct path. I can grind the
numbers for you if you want later (I'm giving a talk tomorrow and need
to get some sleep).


No need, but thankyou. I read about them a bit. I get the idea that they're
huge, totally impractical as a spot fix for a few rooms in a basement flat.

What is there to keep the amplifier from amplifying the "mush"?

Plenty. The mush is very localised, some widget (likely a wireless net box
or router) in the upstairs flat, it is not detectable beyond a quarter of the
distance to my outside antenna. Hence, wondering if a tiny boost and an
indoor dipole might be enough to overcome the immediate locality without
annoying the neighbours. See, if that mush does not reach the outdoor antenna
in any measurable degree, it seemed to follow that a tiny boost to adequate
levels might also fail to reach that outdoor antenna, and thus feedback might
be avoided, as well as unwanted transmission strength beyond my boundaries.
Purely speculative, but it seems logical enough to 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.

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

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

[Lostgallifreyan]

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.

[Jerry Stuckle]

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

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