I'm am referring to the 414khz beacon putting out PYD. When I say CW
mode, I am referring to the mode of the radio, not that the signal is
being sent in CW. NDBs use AM, with a tone to send to Morse code. Since
they are AM, the carrier is always present. Put the radio in CW mode
and use a CW filter, then you get a tone due to the presence of the
carrier. The signal strength of this tone can be used to detect the
null.

The loop is untuned, so Q isn't an issue.


Lumpy wrote:

miso@sushi.com wrote:

I'm quite sure the null is better
than the directional antenna

Then in approximately what manner
are you hoping to improve what parameter?
You want a stronger null?
or
You want more sensitivity?

They aren't exactly the same. Your smaller
loop is probably less sensitive but has
a higher Q, even if it's nowhere near tuned
to the freq.

Stick that smaller loop in front of the big loop.
Make the small one passive and the large loop active.
Vary the distance till you get a stronger
signal. That will be an increase in sensitivity
and an even bigger increase in selectivity (stronger null).

You're relatively close at 10 miles. If you were several
hundred miles, I'd suggest experimenting with a driven
broadside. Both loops active, side by side.

... It would be best to have a meter on the AGC,
but I don't have any radios with such a tap from
the factory...

I thought all S meters were coming off the AGC.

If you have the ears for it, I would trust headphones
before any kind of meter, digital or analog.

What's the nature of the signal that you're
DF'ing? CW, I presume. Theoretically it should
be much easier to DF a CW signal if you don't
know (or aren't tuned to) the exact RF freq.

Finally, 10 miles isn't very far, in terms of
where I assume you're working. You ought to be
able to almost shine a spotlight on the darn
thing at that distance. So I presume there's
some terra firma inbetween you and the xmitter.
Can you hit it from three directions and form
a "triangle of probability"? Once you have an
RF picture of where it "should" be, then look
at the topo to find where it "could" be. If
it's a transmitter, humans have to get to it
to service it.


Lumpy
--
Were you the voice of Casper?
No. Popeye, Snagglepuss and Wells Fargo Bank.
www.lumpyvoice.net