[time-nuts] Active LF Antennas

GandalfG8 at aol.com GandalfG8 at aol.com
Fri Jul 20 05:10:37 EDT 2007

In a message dated 20/07/2007 03:51:20 GMT Daylight Time, kc0vsj at yahoo.com  

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....
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 
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:-)


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