[time-nuts] Active LF Antennas
GandalfG8 at aol.com
GandalfG8 at aol.com
Fri Jul 20 09:10:37 UTC 2007
In a message dated 20/07/2007 03:51:20 GMT Daylight Time, kc0vsj at yahoo.com
writes:
Brooke - you scored a bullseye on that one. I had a
couple of false starts, but got an email back from
Frank Gentges suggesting I contact Far Circuits for
the PC boards ($11.50 for the set which includes
shipping). Now to obtain the rest of the parts...
-------------
If you want to make a quick start on LF try a Google on "pa0rdt" or just
take a look at this....
_www.veron.nl/afd/voorne_putten/Lezing/www.veron.nl/aMini-WhipGeneralDescripti
on%5B1%5D.pdf_
(http://www.veron.nl/afd/voorne_putten/Lezing/pa0rdt/pa0rdt-Mini-WhipGeneralDescription[1].pdf)
Via Google you''ll find info on work by Roelof Bakker aimed at reducing the
element size on an active vertical and the pdf shows the result.....
a complete active antenna on a single PCB 90mm long and 30mm wide:-)
There's been quite a lot of online discussion on the pros and cons of this,
so don't really want to get drawn into it all again, but I have built them and
they've worked well for me.
Using a mini drill with an end burr tool to cut the PCB, or just a hobby
knife will do, the module as described in that pdf can be built in a couple of
hours at most, including the PSU interface.
The 2N5109 suggested works fine but I've also used a 2N3866 with similar
results.
I've used one with a 2N3866 to receive the 17 KHz SAQ transmissions both
from south east England, inland approx 25 miles north of London, and from the
west coast of Scotland, in the middle of the Clyde estuary. In England the
antenna was probably 5 metres above ground level, in Scotland approx 4 metres
above sea level.
MSF on 60KHz is very strong via the mini-whip here in Scotland, even given
the lashed up nature of the test support, but since their move north that's
probably to be expected:-)
HBG and DCF77 are usable too, JJY has so far not been seen:-)
My eventual intention for the mini-whip, as well as using it in it's own
right, is to use it as a "spotter" for my rotator mounted Wellbrook loops so as
not to miss things in the null.....
the best of both worlds:-)
regards
Nigel
GM8PZR
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