On 10/05/2010 11:52 PM, Bob Camp wrote:
Hi
Ok, the next layer to this onion is the antenna. At 100KC your antenna is 35X
smaller than it is on 80 meters foot for foot. In other words, your 100' tall
vertical on 80 equates to a<3 foot tall antenna at 100 KC. QRP on 80 with a 3'
transmit antenna anybody? Been there done that, not much range at all. At VLF
forget about transmitting with a horizontal antenna unless you are airborne.
It's not just the antenna, the ground counts as well. If you are by the
seashore that may not be a big deal. If you are inland, prepare to lay many
very long radials.
----------
After that you hit signal to noise. The receivers worked as well as they did
because they had an enormous signal to work with. There's an amazing amount of
crud running around down below 200 KHz these days. Even for timing you need a
lot of signal to get good results.
Bob
KB8TQ
Ham for way more than 30 years....
Well, in the OLD days, Alexanderson extended the antenna using a coil.
That's how the 127 m high antenna towers of Grimeton transmits the 16,7
kHz of 18 km wavelength signal across the atlantic. The modulation was
CW in 80-speed, but anyway. That transmitter has several interesting
features in it for its time... like feed-forward frequency stabilisation.
Cheers,
Magnus
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