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Bob, >werent there some tests using the sewer pipes as antennas ?
That was a Dilbert comic Broadband Over Sewer Lines a parody on BPL.
--
73 Warren K2ORS
WD2XGJ
WD2XSH/23
WE2XEB/2
WE2XGR/1
On Mon, Feb 22, 2010 at 6:31 PM, <[email protected]> wrote:
werent there some tests using the sewer pipes as antennas ?
the cast iron increase in IR losses would be off set by the diameter
of the Pipe ?? I kinda remember something about that some years
ago
Bob K3DJC
Pete,
what about putting a large (1..10nF) cap
from the antenna base to ground ?
It would reduce the required inductance
with a factor 10 to 100 and at the same time transform the high loss
resistance (I gues 1kOhm or more) to a more convenient value.
Of course the cap needs to handle the
high antenna voltage, so power should be more modest than 780
Watt.
A ready available source of HV caps is
RG8 / RG213 or similiar coax cable that can handle many kV's. At 101pF/m you
would 10 to 100m cable.
73, Rik
Verzonden: maandag 22 februari 2010
23:43
Yep Rik
So how do I load it?
I agree there is about 780 Watts being disapated in the coil so it
would act like a one bar electric fire while the wire held out before
melting.
I have other options of about 400 watts, 250 Watts and about 100
Watts of audio to try out.
I need a plan that does not contain unobtainum like most of the
RSGB designs in the LF Handbook.
I want to use an air core transformer if at all possible.......
there is a lot of pontificating on this reflector about
this subject but I am looking for a practical method of loading a
wire antenna and need help, ideas-wise.
If I can load it with any of the power levels
above there are LF stations who may cooperate in doing an RX
test like G7NKS about 6.5 km away possibly G3xiz or
M0jxm roughly 10km away.
May be trying to load a piece of wire, which is a miniscule
fraction of a wave length, in the conventional way is not the
answer.
So I am open to ideas (practical ones)......
anyone??
Pete,
2.5km Cu wire of 0.2mm has a
resistance of 1345 Ohm.
So even if the coil doen't get
hot by the HV it certainly will by the dissipated power.
73, Rik ON7YD -
OR7T
Hi Group
Using software to calculate what I would need to load my
inv "L" on 8.9 kc/s with my 8 Ohm O/P 800 Watt audio
amp I get :-
A coil/transformer of about 1 Henry which with my air cored
former is 1400 turns,
2.5 km length, of 0.2mm diameter wire.
A coupling loop of about 2 turns.
Creating an antenna current of about 1 amp being driven by
about 60kVolts. Making a coil that will be getting pretty
hot!!!!! Probably red hot.
Any suggestions??
All we need is a wire strung between K2
and Everest summits and fed from base camp
below? -----Original Message----- From: [email protected]
Subject: Re:
LF: VLF_8.79 kHz No license is required in the US below
9kHz. I agree with Mal its very difficult to radiate a
signal on 137kHz, let alone 9kHz! -- 73 Warren
K2ORS
WD2XGJ
WD2XSH/23
WE2XEB/2
WE2XGR/1 On Mon,
Feb 22, 2010 at 11:10 AM, ALAN MELIA < [email protected]>
wrote:
>
Hi as far as the Uk is concerned it is not allowed. You
probably need to
contact Andy G4JNT for details he did
approach the regulator at one time
maybe around 2001/2 when
Geri was doing his tests the answer as I
remember
was:-
> Frequencies below 10kHz are not
allocated by International Treaty but we
control all
frequencies between DC and gamma rays, and no we will not
be
issuing any licences for that region.
>
> I
believe that was the RadioCommunications Agency things may be
different
now with Ofcomm. The best person to know whether
an approach would be
worthwhile would be John Gould G4WKL
who nursed the 500k stuff through.
>
> Alan
G3NYK
>
> --- On Mon, 22/2/10,
Stefan_Schäfer
>>
Date: Monday, 22 February, 2010,
11:32
>>
>>
>>
>>
>>
>>
>>
>>
>>
Ok Roger,
>>
>>
>>
>> And
do you know if f<9kHz is free for other countries
in
>> europe as
>> well? What about the
UK?
>>
>>
>>
>> If such a
grounded dipole is best, than it is easy to build
>>
a big
>> antenna without the problems we have on LF
(getting the
>> wire high above
>> ground).
So we also could try big/long antennas. Waht do
>>
you mean with
>> amateur levels? Power range is
clear, something arround
>> 500W+-6dB.
But
>> the antenna? Sure, if you think about building
an antenna
>> in the
>> garden, say 2x20m,
is not very effective but what about
>> 2x500m in
a
>> forrest, perhaps with the loading coils (which
will be on a
>> ferrite
>> toroid i think)
mounted 300m apart from the center? That
>> could
be
>> interesting and easy to try. No tower, no earth
radials,
>> just 2 wires
>> hung up on some
trees and measured the impedance at the
>> feed
point,
>> that would be a first
step.
>>
>> This antenna will still be bad
but what we are doing -on LF
>> it is the
>>
same- is beeing fascinated to reach a good distance
and
>> make some
>> contacts at very low
frequencies, although it would be much
>> easier
on
>> 40/80m...
>>
>> And so, if
one would reach 50km with such a short dipole,
>>
the
>> fascination would be enormous, isn't it?
;-)
>>
>>
>>
>> Has
anyone, except Horst, tried such experiments as
well?
>>
>>
>>
>> With the
ground wave, one could reach the whole europe, i
>>
expect. But
>> that are
dreams...
>>
>>
>>
>>
Stefan/DK7FC
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
Am 22.02.2010 11:03, schrieb Roger
Lapthorn:
>>
>> At this frequency,
widely spaced, grounded
>> electrode pairs
are
>> probably the best "antenna". There
are
>> references to how these work in
>>
the literature (for example NATO AGAARD papers from
the
>> 1960s,
>> available on the internet I
believe) and on one of the
>> German ham
sites
>> (DK8KW) - see http://www.qru.de/#vlf . >> >>
Don't expect great ranges: up to 10kms is a
fair >> aim with modern >> signal
processing technology and reasonable (amateur >>
levels) available >> power. Project Sanguine achieved
worldwide coverage to >> submarines at >>
76Hz (yes Hertz!) but used enormous power and
antennas >> stretching for >> 100s of
kms. >> >> 73s >>
Roger
G3XBM >> >> >> >> >> >>
2010/2/22 Stefan Schäfer >> < [email protected]> >>
>>
Hello
Horst, >> >> >> >> That
sounds really nice. If it would be easy to find
some >> motivated OMs >> in the near field
(31km) ;-), that would be an interesting >> field
to >>
test. >> >> >> >>
Yesterday i have thought about possible antenna >>
configurations for that >> range and got the idea
that one could use a forrest as an >>
antenna >> tower. There, you could hang up 100s
meters of wire, in >> series and in >>
parallel. You do not need to have that area beside
your >> house. Nobody >> will see the wire
and nobody will care about it. >> >> Since
summer 2007 i have a horizontal loop antenna
mounted >> in some >> trees on my hill with
excellent results on all HF bands and >> also
160m. >> The loop has 130m and is mounted up to 12m
above ground. >> Perfect >> matching from
160m to 10m with my symmetric tuner. I even >>
tried >> matching on 2200m without a problem but with
bad ODX >> results, of >> course. But if one
would try 2x 10*100m on VLF, the ODX >> would
be >>
interesting... >> >> >> >>
JO30OT is abt 160km from JN49IS and thus a little far
i >> think
;-) >> >> >> >> What is
your RX antenna and have you already catched some >>
commercial >> VLF stations in that range? Are there
some? >> >> >> >> 73,
Stefan >> >> >> >> PS: One
can be sure that there will never be SSB operation >>
;-) >> >> >> >>
________________________________ >> >> >> >>
Von: [email protected]>>
im Auftrag von Horst
Stöcker >> >> >> Gesendet: Mo
22.02.2010 09:29 >> >> An: [email protected]>>
>> >>
Betreff: RE: LF: AW: Beaconing on 8.79 kHz in
QRSS >> >> >> >> >> >> >> >> >>
Hallo Stefan, >> >> >> >>
there was a notice in Funkamateur 12/05, S. 1287, that
in >> DL the range >> <9kHz is
free. >> >> >> >> I could
not believe that so I asked the BNetzA and after a >>
while I got >> a letter which confirmed
that. >> >> >> >> So there
nothing you've got to do for getting a >> licence.
You do not >> need
one. >> >> >> >> There is
no limitation of technical parameters like >>
bandwith or
power. >> >> >> >> Hard to
believe in german, but obviously
true. >> >> >> >> My QTH
is Siegburg
JO30OT >> >> >> >>
Horst >> >>
___________________________________________________________ >> >>
NEU: Mit WEB.DE DSL über 1000,- ¿
sparen! >> >> http://produkte.web.de/go/02/>> >> >> >> >>
>> >> >> >> >> >> >> >> >> >> >> >> >>
-- >> >> >> >> http://g3xbm-qrp.blogspot.com/>> >>
http://www.g3xbm.co.uk>> >>
http://www.youtube.com/user/G3XBM>> >>
G3XBM GQRP 1678
ISWL >>
G11088 >> >> >> >> >> >> >>
-- >> ---------------------------- >>
Dipl.-Ing. Stefan Schäfer >> Institut für
Umweltphysik der Universität >>
Heidelberg >> Im Neuenheimer Feld 229 >>
D-69120 Heidelberg, Germany >> >> [email protected]
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-- 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1
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