Hi Dave, LF,
Yes, a transverter would be an other possibility but
it would be much more complex I think, just when regarding the needed power
(compared to a LED). And you would get new problems when you receive on a “new”
frequency, e.g. in the 2m band when there is another noise that is not coming
from LF ;-)
I have a further idea:
DL2CH, Hans-Hellmuth Cuno (who was even qrv on LF
before some years) presented a laser TRX
in the CQDL (I think 2001). I have built this TRX and did some fascinating tests
with a simple laser diode out of a laser pointer. I satisfactorily transmitted music/AF
via the laser beam on a distance of 200m without a noticeable quality loss.
Instead of a transmitting LED and fibre optic
cable it should be possible to transmit a LF signal via a laser beam to the
shack. We could call it a 2,2km/650nm transverter ;-)
Let’s imagine someone has a garden in a
distance of 200m, perhaps on a hillside apart the city where no qrm is, but
with a road between the house that makes it impossible to use a cable. So he
could operate e.g. a grabber to the internet from that clear region! Sure, if
there is strong rain or fog and so on, it will be difficult but that are all
possibilities, one could try without the need for much energy! I would try this
with my laser TRX but there is no need for me (not yet) in the moment.
As we know, there are existing internet links via
laser beams since many years…
Another word to the fibre optical transmission:
Sure there are many methods suppressing noise coming from the coax screen. The
optical solution is just one. But I think the advantage is, that this method
decouples the preamp from the RX for 100%, say with an attenuation of
1000000000000000 dB (to come back for joking ;-) ). There is no need for
choosing the right core out of the right material and the right number of turns
at both sides of the right cable that is placed in the right way and so on and
on. If the optic method is used, this theme is just finished, just like the
question “would it even be better when I apply 10 turns more or take 2
cores and/or bury the coax 5m into the earth?”
Perhaps it’s no so easy as I think but in
the moment it seems to be a good solution for me that is really working fine.
GN or GM de Stefan/DK7FC
73, Stefan
This is very interesting. I have a MiniWhip on a pole some distance
from the house, and it seems that most of the interference (ADSL hash) seems to
be re-radiated by the coax outer and picked up by the antenna.
