I finally got the FT891 and DM330MV power supply I'd been waiting on for weeks.  The only feedline I have on hand is 100' of RG8X, lots longer than I need to get into the shack.  Once the power supply showed up, I quickly threw together a 40m dipole in the dark using scrap 18ga speaker wire and a Pomona cobra head.  Using a NVA I trimmed the wires and got the SWR down to 1.13 in the lower end of 40m phone.

The crazy thing is that I didn't take the time to elevate the antenna, I just set it up NVIS style with bamboo garden stakes, zipties and some 550 cord.  The wire is only 5 feet above the ground.  Yet tonight I made a great contact to western NY state, 590 miles as the crow flies.  I've gotten plenty of such contacts out to the midwest, all with 59 reports.  My understanding is that NVIS is good for the 200-500 mile range, but I'm just amazed that my junky little antenna is doing so well.  This is using 100W from the 891.

My home is at the top of a hill so maybe that helps, but I thought NVIS sent most of the signal steeply upward anyway.  Maybe I'm just getting lucky with the propagation right now.  I'm excited to see how far I can reach out once I get a shorter feedline of better quality coax, and get an antenna up high in the air.  The dipole is fine out in the front yard now, but for a permanent base antenna I'm leaning towards a EFHW.  I just need to decide if I want to try to cover 80m or not.

NVIS is Near Vertical Incidence Skywave. Signals that are going up at very high angles, strongly reflected by the ionosphere back to earth.

Considering the ionosphere is 200~400 miles up, you see how steep of an angle you need to get reflection back to short distances.

Hopefully you know that NVIS is only possible on some of the lower frequency bands and is dependent on ionospheric conditions. Conditions are so poor some days that NVIS isn't possible on 40m during the daytime.

Won't make any difference.

100 feet of RG-8x is 0.9dB loss. 50 feet of LMR400 is 0.3dB... you will never be able to hear the difference in 0.6dB. Never.

In some cases the low antenna can actually be advantageous. They're very poor at low angle/long distance signal, which in the case of 40m in particular will tend to exclude foreign broadcasters and other sources of noise and interference.

So-called EFWH's tend to be a lot noisier and more finicky. If you can put up a balanced antenna, I would recommend staying with them.

How do you like that 891? I have a couple on the way, been waiting forever! Your dipole sounds awesome. I wouldn't ditch it for an endfed. I would add the end fed to the antenna farm though. Sometimes I get noise on my dipole in the front yard that my EF in the back yard doesn't pick up and vice versa. I'm going to order some of those BNC binding posts for antenna playing, looks like the ticket.

When you are happy with your radio shack and find you aren’t going to move or change your antenna location that much there is nothing wrong cutting off the excess coax, leaving you some extra on the original line.  Solder/crimp on a new connector and then you can do the same with your cutoff piece of coax, making short cords and patch cords.  

I have a 150’ of RG8 right now on my OCFD dipole.  The extra is a nuisance and it will get trimmed soon.  

I am still setting up,.....working the permanency from the antenna to the shack....the other antenna, a Hustler BTV5 vertical about 200’ from the house run underground in conduit.  The shack end isn’t settled yet.  still have to drill through the house, hook into the house ground with the new ground.  I pick at it.  For now the coax is outside the window and I have to open the window and grab the coax.  That won’t fly in mosquito season or the dead of winter.

I have my larger jawed crimper for 0.400 thick coax but need another set of jaws or another crimper for the RG8 1/4 inch size.

If this knucklehead can cut and make a cord you can.

Even a low dipole while mostly radiating up, will have some signal radiating at low takeoff angles

So when propagation conditions are good, you can make long contacts it is just that the signal power in that direction is severely reduced.



Look at the dB difference at the 75 degree line, 15 degree takeoff angle relative to the horizon. The signal is very small but there is some.

Look at the 60 degree line, 30 degree takeoff angle, it almost doubles.

So when condition are good, you can make contacts at those takeoff angles even though they are 10-20 dB down from an antenna at 65 feet

I look at that series of height related diagrams and think of proofing a yeast bread and then maybe over proofing as the straight up signal energy moves.


Yea I know silly, optimum pattern, deflating dough.

Awesome, and you're right, you just have to go for it. I reminded myself of that last weekend. I got up early and decided not to workout so hopped on the radio. With 100w and an endfed that's hanging horizontal at 5.5ft high I hit Japan from Texas on 40m LSB. Same antenna, I tried out the new TX_500 I got and with 10w hit NC from TX and he thought I was on 100w. Sometimes you'll surprise yourself, but you never will if you're waiting for the perfect condition.

oops, wrong thread

Gamma, thanks for the point about RG8x HF attenuation, I had uhf/vhf on the brain.  You are clearly a man of precision!



That's my situation too.  Nothing permanent set up yet.  Just running the coax through the window using a cut-down pool noodle to seal the gap.  My overall approach, though, is towards a rig that is portable, so that lends flexibility.



Wow good work man!  Tonight I got my longest contact yet, 870 miles to northern New Hampshire.

I have always been a fan of full size, loop antennas. You'd be surprised with a corner fed, horizontal delta-loop antenna on 40 meters (as an example). Get it up high and enjoy great contacts. Loop antennas tend to be a lot quieter than dipoles and significantly quieter than verticals or end-fed antennas.

I raised my speaker-wire dipole up to about 12' yesterday, then last night made a contact to Wyoming at 1280 miles away.  Responded to a CQ from Mexico too but I couldn't get the guy's location.  He reported a foreign callsign that I didn't know how to look up.

Today I re-checked the dipole's SWR with my VNA.  It had crept up to 1.52 from 1.13.  I suspect the speaker wire got stretched when I raised it and re-tensioned it.  Gonna get some flex-weave wire to make the next antenna.

If my rig's max power is 100w, what's the lightest gauge antenna wire that's functional and durable?

There may be other ways to do it, but I have been using the call sign search box in the upper left corner on https://www.qrz.com/ and, so far, it has been able to provide foreign license info as well as domestic. Mailing address is not always present, but general location seems to be there.

If you got any sway from trees or masts that sway a bit on their guying I wouldn’t go lower than a 14 ga wire.  I think snapping a wire is the bigger risk than heating a wire.  I have a bungie cord at one end of my OCFD.  It is set up as a shock absorber with a length of longer cord run next to it that will hold it up if and when the sun kills the bungie cord.  


I pulled some underground UB three conductor wire up from the old pool,....solid, jacketed 12 ga that I might recycle as an antenna, cobbling a 80m fan dipole out of, or use it in the ground to give me a handful of longer radials.  

OP


 consider a hexbeam for 6-20m.     You will be working DX around the world.    I built one for a less than $400.     It's 21 ft in diameter and could be installed on the roof of your house.
It can be turned with a cheap tv rotor.    


I used plans from this website   https://www.hex-beam.com/description/


8nBAIT

The Higher a dipole is above ground, the LONGER it must be to maintain SWR.  at a given frequency.   LOWER=Shorter; HIGHER=Longer

Add a couple feet of wire to each end and re-cut the dipole for the new height, OR,  1.5:1 SWR is not a deal breaker!  I personally wouldn't bothe for the .40 SWR.

Dang, I knew the dipole's height affected the radiation pattern but didn't realize it affected SWR.



I think you're right, as I was able to work a maritime operator off the coast of Trinidad (about 2160 miles away) with my junky antenna.  I am curious, though, about the degree to which all that saltwater helped the propagation.  Still, pretty cool.

Height above ground changes the impedance of the antenna. A dipole in free space is like 72 ohms, but the impedance changes depending on distance from ground. If you're super wonky you get it .16 wavelength above ground for a perfect 50 ohm match

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