[Lowfer] Band conditions

[Jay Rusgrove]

Larry

Thanks for the capture. Glad to see VD is good copy there.

Yes, my loop is pointed east/west.

I have used my TX loop for receiving and measurements this summer on TAG
and WA shows about a 1 to 2 dB s/n advantage over my 17 turn, 5.5 ft per
side tuned box loop. I find that about 24 - 28 dB of attenuation between
the TX loop and the receiver input is required. Otherwise, the
background band noise activates the receiver agc.

A couple weeks ago I installed a single turn 100' diamond shaped RG-58
loop untuned receive antenna. It's set up with the braid as an
electrostatic shield - at the top of the loop there is a 1 inch gap in
the braid. The free ends at the bottom of the loop have N connectors
that attach to each side to an aluminum box. The primary of a broadband
transformer has one end connected to each of the center pins - at the
moment it's "floating" with no connection to ground. The secondary of
the transformer feeds a heavy duty bipolar (50 mA idling current!)  2.5
dB noise figure 50 ohm broadband fedback preamplifier. DC is fed to the
preamp via the output coax. The transformer I'm currently using has 5
turns on the primary and 25 turns on the secondary wound on an FT-37-75.

Haven't had time to do complete testing or optimization of the
transformer, but it works pretty well as is down to at least 10 kHz. The
electrostatic shielding removes much of the local noise and s/n
measurments on TAG and WA look promising. At the moment the bottom is
only about 3 feet off the ground. I'm going to try elevating it to 100
feet at the top. Also plan to try a similar antenna with 200 feet of
RG-58.

If you're interested I will let you know what I find as I do more
testing.

Jay



Larry Putman wrote:

> Hi Guys!
>
> Here it is 11am and VD is blasting in and if you look
> carefully in the upper left corner there is WA.
>
> I suspect that in a month or so WA will be stronger yet
> during the day.
>
> Bill are your loops still rotating?
> Jay did you tell me your loop was favoring east/west?
>
> If Dex would join you on this freq I am sure he would be
> on this capture also.( Hint )
>
> Since these TX loops seem to be doing such a good job
> would a loop built similar to the TX loop work better
> as a receiving loop also??
>
> I know that Mitch's 12' Octo loop is doing a fantastic job so
> what would a very large coax loop do?
>
> Larry WB3ANQ
>
> _______________________________________________
> >From the Lowfer mailing list
> Send messages to: Lowfer@mailman.qth.net
> To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer