Okay, trick question. Of course I'm crazy. :-)

But seriously... I've been thinking of antennas that would work (or at
least tune reasonably) on 80 and 160 meters that wouldn't require taking
over my neighbors' yards (small city plot) and would be acceptable to the
antenna restrictions of my non-ham partner. And I like to experiment.
So I was thinking, could I pull off using my house wiring (possibly up
to the pole pig) as a very random long wire antenna, using a high pass
filter network to isolate the 60Hz power but let the 1.8MHz+ signal pass?

Some parameters and things I've considered:
Max TX power would be 100W. Of course I'd start QRP and ramp up.
I'd build a T network filter (2 caps and 1 inductor) with a rolloff
frequency around 1MHz.
Some of the house wiring is in conduit or MC cable, which of course would
shield the signal in those areas.
I share a pole transformer with at least 3 other houses.
I've worked with 120 before, and respect it's great power (pun intended).
I did see a thread a while ago that mentioned a carrier current system in
a dorm environment, though that seemed to aim to keep ERP to a minimum,
IIRC.

Questions:
What voltage rating should I be using for the caps? I'd figure at least
500V, but would I need more for the RF?
Should I expect appliances and electronics in the house to blow up (or
otherwise be damaged) by upward of 100W coming down the power lines?
Would it be effective only as a TX antenna? i.e. would RX noise be too
great even with the filter network?

Any thoughts or advice would be appreciated. It would be neat to have
a working antenna (however well it might work) that was completely
concealed, even if I end up using my 40M dipole as an RX antenna. It
would also save on buying antenna wire.

Thanks in advance, and glad to see Usenet still alive after all these
years (was first on in 1991).

~~Anya, KC2ZAK, FN13

--
| Anya Turnquist | an4ya2 ^at^ turnquist ^dot^ name
| http://www.turnquist.name | (remove #'s, etc. to reply)
| Be who you are and say what you feel, because those who mind
| don't matter, and those who matter don't mind." -- Dr. Seuss

In article ,
Anya T. wrote:

Should I expect appliances and electronics in the house to blow up (or
otherwise be damaged) by upward of 100W coming down the power lines?
Would it be effective only as a TX antenna? i.e. would RX noise be too
great even with the filter network?

Some folks used to try to use house wiring as an "incredibly powerful
TV antenna" (via a simple capacitive coupling). Fancy-looking gadgets
were sold through catalogs, often for high prices, to do
this... actual parts cost was probably a dime. By all accounts they
worked poorly - far too much RF "hash" on the mains, even in the days
before switching power supplies became common - static-filled,
multipath-ridden ghosty TV images were about the best you could
expect. For weak signals such as ham transmissions I doubt you'd find
it worth the trouble.

As to transmitting? I'd expect that you'd probably succeed in
completely disrupting the reception on any TV or radio in the house,
or on the same mains circuit. Might even fry something in the front
end, crash computers, etc. - the RF filters built into power supplies
are designed to block low-level RF noise, not a shrieking holocaust!
You'd certainly trip every GFI in the house the instant you keyed
up... they'll sometimes trip just from having near-field coupling between
the house wiring and a dipole.

These days, "pole pigs" sometimes have capacitive bypass built in, to
allow over-the-powerline signals from the power company to reach the
power meter. Even for those that don't, you could probably figure
that you'd be coupling a significant amount of power through the
transformer via inter-winding capacitance. So, the 'pig probably
won't block your signal very effectively.

So, I suspect that the interference complaints from your neighbors
would probably start churning in very quickly. The power company
would probably be miffed when they found out. If your tuning placed a
high RF voltage on the pole pig windings and started some arcing
within the pig... well, that could be both embarrassing and
expensive. Since there's no way any such transmitting attachment to
the mains would be UL certified, you could easily be found at fault
for any Badness which occurred.

Sounds like a Bad Idea to me, unless you like interesting fireworks.

Anya T. wrote:
Okay, trick question. Of course I'm crazy. :-)

But seriously... I've been thinking of antennas that would work (or at
least tune reasonably) on 80 and 160 meters that wouldn't require taking
over my neighbors' yards (small city plot) and would be acceptable to the
antenna restrictions of my non-ham partner. And I like to experiment.
So I was thinking, could I pull off using my house wiring (possibly up
to the pole pig) as a very random long wire antenna, using a high pass
filter network to isolate the 60Hz power but let the 1.8MHz+ signal pass?

Using house wiring? Bad. Of course, things like X10 do it.
So does power line IP. Both are low power and are designed
to minimize emissions, so they do not compare.

Using external wiring from the pole? OK in theory but just about
impossible in execution.

You would want an isolation network (high- or bandpass) at each
end. Good luck in getting anyone to install those; and good luck
in getting it all approved by the inspectors.

And then you have to think about how to drive it.

What happens to your transmitter if a high energy transient, such
as might be induced when lightning strikes nearby, shorts out an
isolation capacitor? What do you have to do to be truly safe?

It's just an idea whose time will likely never come.

George

P.S. I was wondering why my little tabletop log periodic TV
antenna seemed to be getting unexpectedly good reception on
certain channels in a 2nd story bedroom until I realized I
was pointing it along the path of the powerline from the
pole. For certain frequencies I suspect it was extending
the antenna length, or even serving as a waveguide. Somewhat
unreliable on those channels, though, and affected by cars
travelling on the street the powerline was running across.

I wrote:

You would want an isolation network (high- or bandpass) at each
^^^^
low-

On Tuesday, September 24, 2013 1:30:52 PM UTC+10, Anya T. wrote:
Okay, trick question. Of course I'm crazy. :-)



But seriously... I've been thinking of antennas that would work (or at

least tune reasonably) on 80 and 160 meters that wouldn't require taking

over my neighbors' yards (small city plot) and would be acceptable to the

antenna restrictions of my non-ham partner. And I like to experiment.

So I was thinking, could I pull off using my house wiring (possibly up

to the pole pig) as a very random long wire antenna, using a high pass

filter network to isolate the 60Hz power but let the 1.8MHz+ signal pass?



Some parameters and things I've considered:

Max TX power would be 100W. Of course I'd start QRP and ramp up.

I'd build a T network filter (2 caps and 1 inductor) with a rolloff

frequency around 1MHz.

Some of the house wiring is in conduit or MC cable, which of course would

shield the signal in those areas.

I share a pole transformer with at least 3 other houses.

I've worked with 120 before, and respect it's great power (pun intended).

I did see a thread a while ago that mentioned a carrier current system in

a dorm environment, though that seemed to aim to keep ERP to a minimum,

IIRC.



Questions:

What voltage rating should I be using for the caps? I'd figure at least

500V, but would I need more for the RF?

Should I expect appliances and electronics in the house to blow up (or

otherwise be damaged) by upward of 100W coming down the power lines?

Would it be effective only as a TX antenna? i.e. would RX noise be too

great even with the filter network?



Any thoughts or advice would be appreciated. It would be neat to have

a working antenna (however well it might work) that was completely

concealed, even if I end up using my 40M dipole as an RX antenna. It

would also save on buying antenna wire.



Thanks in advance, and glad to see Usenet still alive after all these

years (was first on in 1991).



~~Anya, KC2ZAK, FN13



It would be bad. Try holding an HT tuned to an AM or HF frequency, near the power wiring in the wall and you will hear massive amounts of noise being radiated. Every one of those nasty little wall warts is pumping noise back into the wiring. It will be impossible to filter it out.