Trying on 6920 AM

[jackson_r]

I'm going to be trying on 6920 AM about 10 minutes from this posting, and will continue for about 20-25 minutes. 

[ChrisSmolinski]

I checked the SDR recording, no sign of a carrier.

[ByteBORG]

I show no activity on 6920 kHz from 0352 to 0435 UTC on the overnight SDR recording.

[jackson_r]

Thanks for the report, rather lack thereof.     I'm only running at 50 watts in to a 6' whip that's mounted just 5 feet above the ground.  Unfortunately with my HOA rules, I don't have many options as I have to keep it out of sight.  I'm going to look at doing some different positioning this weekend, might try on USB as well after I do that. 

[Stretchyman]

6' whip at 5 feet may get you 2 blocks with a CB radio but on 40m your going to need something a bit longer!

For NVIS a dipole made from thin (invisible) wire can be 7' from the ground and can run along a fence top but will need to be 70' long.

I've done some experiments recently and can put a decent signal into Holland from the U.K. about 400 miles with 10W.

This will only work during daylight hours, so your going to need a 35' vertical at night and you'd probably work from coast to coast, 2000 miles or so.

Use what you can but don't expect you're going to get anywhere with a 6' antenna at these frequencies.

OK!

[jackson_r]

6' whip at 5 feet may get you 2 blocks with a CB radio but on 40m your going to need something a bit longer!

For NVIS a dipole made from thin (invisible) wire can be 7' from the ground and can run along a fence top but will need to be 70' long.

I've done some experiments recently and can put a decent signal into Holland from the U.K. about 400 miles with 10W.

This will only work during daylight hours, so your going to need a 35' vertical at night and you'd probably work from coast to coast, 2000 miles or so.

Use what you can but don't expect you're going to get anywhere with a 6' antenna at these frequencies.

OK!

I appreciate the cold hard truth, Stretchy.  I actually do have a 40 m dipole sitting in a box that I've been thinking about stringing across the top of my 6.5' privacy fence in the back yard.  Plenty of room, but the only thing that's kept me from trying it is first, that I'd have to run about 100' of coax to get out there from the shack, and also the fact that I've read somewhere that a fence top mounted dipole like that is going to be very focused and directional, and I didn't know if that was going to cause me problems.  But I'm willing to try anything once.   

[Antennae]

You could also try a magnetic loop. Those things are high performance for their size. Make a 9' diameter bad boy out of plumbing copper pipe!

[jackson_r]

and I forgot to mention the 1 KW amplifier I have arriving in the first week of December.  That should help me play with the big boys.  Or maybe something will explode.  Either way, it is exciting.   

[Stretchyman]

OK with the amp but you'll do fine with 10W and an antenna that works.

1KW will probably just wipe out all the local phone/tv/radio etc and get you into a heap of trouble.

The loop BTW is a good antenna but your situation (as I understand it) needs something more covert.

[jackson_r]

OK with the amp but you'll do fine with 10W and an antenna that works.

1KW will probably just wipe out all the local phone/tv/radio etc and get you into a heap of trouble.

The loop BTW is a good antenna but your situation (as I understand it) needs something more covert.

Well, I was being a bit facetious.  While it's indeed a 1 KW amp, I have no intention of using it as such.  Once I get a good antenna up and running, I might use it to drive 200-300 watts occasionally.  Today I'm going to tack down my 40 meter dipole on the backyard fence and see what that does. 

[Stretchyman]

Cool, no worries. Try a folded dipole low to the ground, the Z will drop and you'll get a decent swr. As long as you have a good take off you'll get fair NVIS. Let us know how u get on.Plenty of online SDRs now to test your metal!

[EliteData]

trust me.
the urge to push more than 200-300 watts will eventually overcome your resistance to do it 

[jackson_r]

trust me.
the urge to push more than 200-300 watts will eventually overcome your resistance to do it  

Oh, I don't doubt. But as I mentioned in another thread here, that last thing I want to do is start blasting across the neighbor's baby monitor.  

I continue to be intrigued by the magnetic loop antenna option.  I spent the better part of the weekend reading up on them and it's definitely something within my skill set to make.  The way our backyards are clustered together, I doubt I could get away with mounting a 9' loop vertically.  Even in the dark, it would look like some sort of UFO had landed in my backyard.  But I've been reading that horizontal mountings can work as well, and that would be a lot less noticeable to the nosy nellies who live next door.  I'm going to try the fence mounted dipole first.  If that doesn't work, I'll consider the mag loop.  

[Stretchyman]

Make sure wire is 'insulated' from fence, wood gets wet and antenna would perform poorly.

Optimum NVIS height is only 8'.

Yes I've been looking into loops as most folk TX on a fixed Freq, make the ideal antenna using a vacuum (fixed) 100pF cap and 22' loop, should give me close to 6.4MHz resonance.

Mounting horiz, you really want to get some height but as you really after NVIS? I guess mounting low may be fine?

Have fun experimenting!

With the wealth of online SDR's it's easy to see if it's working!

Stretchy.

[EliteData]

with my testing and experience through the many years, if youre going to mount a horizontal dipole, i find that 30 feet above ground with at least 10 feet from absorption obstacles seems to be at the minimum threshold for optimum performance but not everyone can afford this luxury.