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Author Topic: 43m pirate TX antenna ideas  (Read 723 times)

Offline Radio Boogie

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43m pirate TX antenna ideas
« on: November 01, 2019, 2153 UTC »
Howdy folks...

I am finally ready to take the jump to the HF "dark side", LOL. I am reviving an old DX35 transmitter which is peaking out to 65 watts CW and about 35 AM unmodulated, into a 60w light bulb.

Audio stage is where I am now, I have not tried to modulate it yet. More than likely, I am going to hack the Speech Amplifier, modulator and controlled-carrier circuits for a 600Ω balanced line. The power supply is not strong enough to convert to plate mod. 

My Audio Chain:
Gates console PGM buss
Optimod 8000 - Composite out feeds my FM, "test" output feeds
Harris Tri-Band AGC
Inovonics 222 NRSC limiter which feeds my MW transmitter

I was a radio engineer and DJ for 30 years. I thought I was pretty well versed in antenna theory. Was I ever wrong! I mean, it's pretty simple to keep an AM or FM broadcast antenna specced (well directional arrays aside) and most of the time, I never thought much about antennas. Any other low-power antennas I've dealt with have been your typical STL/RPU, SW random wire RX and CB antennas. Granted, I was probably more in my niche tweaking audio and processing equipment than phasors and impedance bridges. The more I try to educate myself on all the intricacies of antennas at HF frequencies, the more confused I am getting.

Here's what I have to work with. Small, suburban lot, as outlined below:

DESCRIPTION OF WHAT THIS IS - Straight up is approx 3 to 6 degrees west of true north. It is a total of approx. 165' deep and 70' wide. The teal boxes with aqua outlines are the house and garage, respectively. Ridgepole of house and garage are oriented east-west. House is a bi-level with basement 36" deep.

The green lines are the chain link fences dividing the yards. The left (west) fence is about 80' and the right (east) maybe 90'. They're probably like 36" high except the north, which has 6' wooden picket fence sections on the opposite yard maybe 3/4ths of the width. The fences do not enter the front yard on either side.

There is a medium-sized Maple (35' tall maybe)  in the SW part of the "parkway". The white blob in the rear-center is a Tea Tree and the blobs to the left are Rose of Sharon shrubs. There is actually a third one north of those under the drop, but I covered it with grass when I edited the pic to remove the large willow trees we had cut down this summer.

The power/utility  drop is the RED LINE. It dissects the yard diagonally from about 40' in the center to the far northeast corner. Utility/power lines run above the north end of the property. A real PITA!

There is a double-height split deck on rear of the house, northwest corner. The high end is to the west, and is about 6' to the floorboards from the ground. In that NW corner of the deck, there is a 15' mast I have my sloper on, as well as a UHF Corner Reflector. I could probably elevate that mast up to about 30' max if I put guys on it. IDEALLY, I would like to put a tower on the middle of the west side of the house, provided I can find one I can afford. Being poor sucks.

I have an old HF ground plane I scrounged that I could hack for low-angle TX antenna. All aluminum and quite old, likely 70's vintage. It is what it is. I could mount it on top of the existing mast. I do not know if it has a loading coil or not, but I suspect it may. When I get it apart I will update as to that.

I have a 6' broomstick helical that I used for my MW TX. It's wound around a 1" PVC pipe and I don't recall what the wire length was. I scrounged the 14g shellacked wire from an old plate transformer with a fried primary. The PVC pipe is wound nearly it's entire length. If nothing else, I could maybe incorporate this as a loading coil in series with the vertical. This would likely be a TX only antenna.

I am really considering an NVIS antenna mounted above the chainlink fence on the left side of the yard. That is a lot easier to use and access than the other parts of the yard.

Another thing I may do in the future is a dipole along the west boundary from tree in front yard to the back. 

I do not have much 50Ω coax, mostly shorter chunks. I do have a *bunch* of RG6, probably a couple hundred feet or more. Obviously, the TX wants 50Ω coax. Then, there are baluns, ununs, all that magic stuff.  This is where the brain bleed starts.

if this was your situation, flat wallet and all, what would you do?



Grundig Satellit 800 ME with 35' sloper
Realistic DX440 with random wire
Realistic DX120 with random wire
Various vintage Portables
Transmitter: Yaesu FT757GX
Inverted V, mounted 20' above a chainlink fence, N to S
Comments and reception reports welcome.
eQSL to radio.boogie@protonmail.com

Offline redhat

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Re: 43m pirate TX antenna ideas
« Reply #1 on: November 01, 2019, 2254 UTC »
Antenna wise, and assuming NVIS is your desire, put up and inverted V along one of the fences with a TV mast or something similar.  If you cant do that, string a dipole fed with RG-6 from the garage to the shed.  It will take some tweaking to get the impedance OK, but shouldn't be that hard.  The old tube transmitter you have won't care about the load anyway, certainly not at that power level.

+-RH
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Offline JimIO

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Re: 43m pirate TX antenna ideas
« Reply #2 on: November 01, 2019, 2256 UTC »
A PL259 male to F female adapter and RG6 will get you from the tx to whatever antenna you decide on. The transmitter will work into 50-75 ohms. If you go with a dipole you can make a 1:1 balun with RG6 also.

~
« Last Edit: November 01, 2019, 2300 UTC by JimIO »

Offline redhat

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Re: 43m pirate TX antenna ideas
« Reply #3 on: November 01, 2019, 2345 UTC »
The above mentioned balun should be considered mandatory and can be made by coiling up 10-20 feet of RG6 at the feedpoint.  It will assure the pattern is as symmetrical as possible and reduce RFI in the your house, and likely your neighbors too.

+-RH
« Last Edit: November 01, 2019, 2355 UTC by redhat »
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline Radio Boogie

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Re: 43m pirate TX antenna ideas
« Reply #4 on: November 02, 2019, 0040 UTC »
I figured as much, Redhat... RFI is a real concern due to close placement of houses here. How would I best construct that coax balun?
Grundig Satellit 800 ME with 35' sloper
Realistic DX440 with random wire
Realistic DX120 with random wire
Various vintage Portables
Transmitter: Yaesu FT757GX
Inverted V, mounted 20' above a chainlink fence, N to S
Comments and reception reports welcome.
eQSL to radio.boogie@protonmail.com

Offline redhat

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Re: 43m pirate TX antenna ideas
« Reply #5 on: November 02, 2019, 0135 UTC »
Coil it up and zap strap it to the feedpoint.  If that doesnt work well enough, you can get a large torroid (T300-2)  and wrap as much coax as you can fit through it.

At 30W, I doubt you'll have much trouble, but every situation and installation is different.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline JimIO

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Re: 43m pirate TX antenna ideas
« Reply #6 on: November 02, 2019, 0528 UTC »
Don't get buried in the theory. Do a search for 'wire antenna calculator' to get some ideas of what will work in your situation. One more thing, even if that tx has been modified with a 3 wire power cord you still want to ground it.

~

Offline Pigmeat

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Re: 43m pirate TX antenna ideas
« Reply #7 on: November 02, 2019, 1040 UTC »
I had a similar layout at my house. 43 meter dipole from a 6 foot mast at the southern peak pf the roof didn't take up room at all. Peak of the mast and feed point was about 35 ft up. I lucked into 1:1 balun at a hamfest as people were loading up for about 5 bucks.

I had a former broadcast engineer living up the hill, he was my audio check guy when the weather was too nasty to go out in the woods. He taught me a lot about audio in the days of analog eq's. I quit the broadcasting from home when the guy next door started requesting Elvis Costello. The Grenades were first class harmonic generators and it loved the guy next door's new metal roof. He was a drinking bud, I didn't have to worry about that ol' boy.

Offline Josh

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Re: 43m pirate TX antenna ideas
« Reply #8 on: November 02, 2019, 2221 UTC »
Very hard, almost unpossible, to beat the efficiency of a dp/inv-v or ocf, but a vertical would still be nice to have in the arsenal. You got a metal roof to hang a vertical atop? A metal roof should make for a fine groundplane.
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Offline Radio Boogie

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Re: 43m pirate TX antenna ideas
« Reply #9 on: November 05, 2019, 1932 UTC »
One more thing, even if that tx has been modified with a 3 wire power cord you still want to ground it.

Indeed. I have a "station ground" that ties everything together to a deep well pipe in my basement. Audio, RF grounds and even the house electrical ground. I'm working on a passthrough jack panel for all my antenna cables to tie the coax shields to that ground.
Grundig Satellit 800 ME with 35' sloper
Realistic DX440 with random wire
Realistic DX120 with random wire
Various vintage Portables
Transmitter: Yaesu FT757GX
Inverted V, mounted 20' above a chainlink fence, N to S
Comments and reception reports welcome.
eQSL to radio.boogie@protonmail.com

Offline Radio Boogie

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Re: 43m pirate TX antenna ideas
« Reply #10 on: November 05, 2019, 1933 UTC »
Very hard, almost unpossible, to beat the efficiency of a dp/inv-v or ocf, but a vertical would still be nice to have in the arsenal. You got a metal roof to hang a vertical atop? A metal roof should make for a fine groundplane.

No metal roof, unfortunately.
Grundig Satellit 800 ME with 35' sloper
Realistic DX440 with random wire
Realistic DX120 with random wire
Various vintage Portables
Transmitter: Yaesu FT757GX
Inverted V, mounted 20' above a chainlink fence, N to S
Comments and reception reports welcome.
eQSL to radio.boogie@protonmail.com

Offline Radio Boogie

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Re: 43m pirate TX antenna ideas
« Reply #11 on: November 05, 2019, 1941 UTC »
At 30W, I doubt you'll have much trouble, but every situation and installation is different.
Indeed, that is the "artform" side of radio!
Grundig Satellit 800 ME with 35' sloper
Realistic DX440 with random wire
Realistic DX120 with random wire
Various vintage Portables
Transmitter: Yaesu FT757GX
Inverted V, mounted 20' above a chainlink fence, N to S
Comments and reception reports welcome.
eQSL to radio.boogie@protonmail.com