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Author Topic: Trying on 6920 AM  (Read 5411 times)

jackson_r

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Re: Trying on 6920 AM
« Reply #15 on: November 30, 2015, 1458 UTC »
Stretchy - I've read some sources that say a properly resonant mag loop antenna will work just fine, even mounted vertically on the ground.  :o  If that's true, I may be able to use one with a vertical orientation and still keep it fairly out of sight.  I guess we'll find out if I end up going down that path.  Right now I have to wait a few days before I can even try my fence dipole.  I had to order in 150' of coax to even make the connection from my rig.   :D

Offline Stretchyman

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Re: Trying on 6920 AM
« Reply #16 on: November 30, 2015, 1543 UTC »
OH, I though he wanted NVIS?

Your 'Distances' are so much 'Larger' over there!

 :D

Str.
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

Offline Stretchyman

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Re: Trying on 6920 AM
« Reply #17 on: November 30, 2015, 1549 UTC »
Yes the loop will be very good and will radiate low and high angle radiation so give you good coverage (local, aka NVIS & DX) when mounted close to the ground.

Remember the rather high voltages which will be around even with 100W = 5KV! so keep it at 10' or so.

You on the E or W coast?

Or somewhere in between?

Str.
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

jackson_r

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Re: Trying on 6920 AM
« Reply #18 on: November 30, 2015, 1555 UTC »
West Coast of the U.S. 

Offline Stretchyman

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Re: Trying on 6920 AM
« Reply #19 on: November 30, 2015, 1600 UTC »
The west is the best they say!

OK, where's your 'Target' audience?

Fellow West coasters, East Coast, Europe or anywhere else?

Str.

'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

jackson_r

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Re: Trying on 6920 AM
« Reply #20 on: November 30, 2015, 1723 UTC »
I would say all points "east."  I'd prefer to attenuate to the west as the feds have an outpost there.   ;)  It's an interesting question that I was going to ask as part of this tangent we've taken on mag loops.  From what I understand, mag loop antennas have a specific area of attenuation out of the axis.  So if I mounted a mag loop horizontally, RF is going to go out in an omnidirectional pattern with attenuation directly beneath and above the axis.  Mounted vertically (and lets say in an east/west orientation), the pattern would be straight up and north/south with attenuation to the west and east.  Orient it north/south and the pattern would be straight up and west/east, with attenuation to the north and south.  Sorry, that all looks like rambling upon reading it again, but I'm just struggling to wrap my pea brain around the directional characteristics of a mag loop antenna. 

Offline Stretchyman

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Re: Trying on 6920 AM
« Reply #21 on: November 30, 2015, 2315 UTC »
Yes the pattern seems the opposite of what You think!

Would be a good antenna for sure, quite a bit of effort.

As your already west I can't work out where the Feds are, on a boat or in Hawaii!
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

jackson_r

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Re: Trying on 6920 AM
« Reply #22 on: December 01, 2015, 0420 UTC »
The little buggers are everywhere, aren't they?  I'm actually about 50 miles inland from the coast and I've got a big metro city due west of me where they have an office.  Not to mention that I've got a couple of Ham towers due west of me in the neighborhood (different HOA, hence the reason they can have a visible antenna and I can't).  I'd rather stay out of their line of "sight" if possible.  I was thinking of orienting a mag loop north/south, with a big piece of plywood wrapped on one side with aluminum foil just a couple of feet to the west of the it.  From what I've read, this should attenuate the signal quite a bit to the west, or at the very least throw people from the west "off" about where the signal is coming from.  I may never build one, but I like antenna theory.   :D

Offline Antennae

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Re: Trying on 6920 AM
« Reply #23 on: December 01, 2015, 0459 UTC »
You could camouflage the loop by painting it white and putting fake vines and flowers on it like its a garden arch. And put a pretty box over the capacitor and paint some silly flower design on it. 
Or you could also get some plastic lattice and fill in the loop with it. And put vines and large fake butterflies on it.

Here's some info from the web that I found after a month of obsessing over the mag loop things (its in my post down the page):
http://www.hfunderground.com/board/index.php/topic,23877.0.html
California Coast
Antenna: random wire

Offline John Poet

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Re: Trying on 6920 AM
« Reply #24 on: December 01, 2015, 0625 UTC »
Jackson,
Trying to attenuate your signal toward an FCC field office probably isn't going to help you.  In fact, they don't actually do their radio monitoring from there.

Read this:
http://freeradiocafe.com/forum/viewtopic.php?f=14&t=3388

Since they monitor from multiple points around the country, it doesn't matter that much which way HF transmissions are "pointed"-- some of them will be able to pick it up.

The biggest issue is to try to avoid being reported by anyone to the FCC-- it's fielding complaints where they spend most of their enforcement energies.  They don't have the resources to do much else.



John Poet

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Offline Stretchyman

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Re: Trying on 6920 AM
« Reply #25 on: December 01, 2015, 0709 UTC »
Wise words!

How true, one can not expect to completely attenuate a signal from an antenna even with a wall of lead!

The signal will bounce off all sorts of things, sure it will be less than the 'forward' direction but still radiate.

I think the 'Flower Pot' etc suggestion is superb and as the man says you're only going to get sussed if you cause interference.

Put the antenna up without even broadcasting!

Str.
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)

jackson_r

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Re: Trying on 6920 AM
« Reply #26 on: December 01, 2015, 1304 UTC »
You could camouflage the loop by painting it white and putting fake vines and flowers on it like its a garden arch. And put a pretty box over the capacitor and paint some silly flower design on it. 
Or you could also get some plastic lattice and fill in the loop with it. And put vines and large fake butterflies on it.

Here's some info from the web that I found after a month of obsessing over the mag loop things (its in my post down the page):
http://www.hfunderground.com/board/index.php/topic,23877.0.html

Great idea!  In my HOA, my backyard can be seen from the second floor of no less than 6 different neighbors.  I think what would make the most sense is to paint something like that a shade of green that closely approximates the green color of my grass.  Or I guess since I'd usually be using it after dark, just to paint it black. 

Good advice as well from John and Stretchy.  150' of coax for the dipole arrives today.  I'll post a "heads up" here once I get ready to try it out and we'll see if I'm transmitting any better.  If that doesn't do much for me, we'll start looking at decorated backyard flower arches.   ;D