VLF ant

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VLF ant

Post by oldtimer on Sun Apr 13, 2008 12:09 am

Of course this not SW but VLF. I'm making an antenna on a 3 ft. square form with taps at 14 turns, 28 turns and 42 turns. When I triangulate for the direction of the incoming sig is it the broadside of the loop that is the receptor side or the edgewise angle? I'm referring to VLF at 150 to 400 KHz. I need to know at which point of the compass is the direction of the incoming signal. I'm referring to the AM BC band portable radios with the rotating ferrite antenna on top for direction finding such as used on boats. Except that I'm using a DX-160. Thanks, OT. Question

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Re: VLF ant

Post by krystallo on Sun Apr 13, 2008 3:35 am

Hey Oldtimer . The edge of the loop picks up the signal.
Otherwise put, one horizontal cross arm will point exactly towards the station (and the cross arm on other side will point away from the station) .

Go to see another VLF'er on board. I work from REALLY low (natural radio /whistler stuff) all the way up through the Afro Euro bcast band/ beacons to 530 Kc.

FWIW, I live about 6 miles inland Boston and on a 75ft longwire 15 ft over a flat apt roof I get longwave B'casts on a number of ,if not "MANY", nights. Not always great, but there. I do get "lifts" at times where some of them come in pretty good.

When I set up at the beach (ie Salisbury, Ma or different beaches on Cape Cod) longwave bcasts boom in on just 75 to 200 ft of wire.
For the lower freqeuency stuff (ie SAQ Sweeden)I've run out 1500 or even as much as 2000 ft of wire and used a 100 ft bare copper wire saltwater ground radial for my return.For this work I use an Icom R-70.

And as sick as I am, I even LIKE lightning crashes (for my weather studies). My fully passive "7" Kc microphonic "system" (no amps /no batteries) gets South America at fair copy and North America quite well w/o much 60 Hz.

When I use the double amped / double graphic equalized version of the system, South America is VERY good and N. America STORMS in. I MIGHT also be getting some other stuff (Africa , Indonesia area,etc ) at "whatever" volume but am not sure- I can't really confirm these ones, although they are probably mixed in w/ the closer louder stuff (from S.and N. America).
On the amp'ed system, 60Hz is scrubbed out to near zero.
Overall quite good considering my antenna has 13.8Kv at about 20 ft on TWO sides .

de K

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Re: VLF ant

Post by oldtimer on Sun Apr 13, 2008 8:32 pm

Thanks for that. It's not like a longwire. You mentioned SAQ. Is that the alternator xmitter at 17.2 KHz? OT

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Re: VLF ant

Post by krystallo on Mon Apr 14, 2008 1:19 am

Yes, SAQ is at 17.2 Kc. during several attempts I only got it once, VERY weak. But my Icom is not spec'ed to operate that low.I'm lucky I got it.
K

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VLF

Post by oldtimer on Tue Apr 15, 2008 1:04 am

Het krystallo. A VLF translator is avail at Palomar Engineers. www.palomar-engineers.com Mod VLF-S $99. I hope to get one. They also said a vertical ant works for that freq. ( SAQ ). I'm going to try a loop and maybe a looong wire. Also I'm thinking of building a 2 meter square multi-loop ant. for lower freqs. with taps at 14-28 & 42 turns tapped at each 14 turn loop. I'm using 14 cond ribbon cable. A comeback from hams and listeners always welcome. OT

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Ant

Post by oldtimer on Tue Apr 15, 2008 1:24 am

You mentioned an antenna at " 13.8 Kv ". What's that? OT Also, what is " Noob " ? OT

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Re: VLF ant

Post by krystallo on Thu Apr 17, 2008 12:31 pm

The 13.8 Kv are the high voltage power lines . My apt is on a corner , so we have power lines on two sides of us only about 20 ft from the antenna and or feed line. I think a noob is a newbie, ie a NEW person to the forum.
K

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Re: VLF ant

Post by oldtimer on Mon Apr 21, 2008 11:21 pm

Noob, OK, I'm not. Re your 13.8 Kv ant, What's the S/N ratio? OT

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Re: VLF ant

Post by oldtimer on Mon Apr 21, 2008 11:23 pm

If you build a vert coiled ant at 90 deg from the pwr lines it may improve reception. OT

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Re: VLF ant

Post by krystallo on Wed Apr 23, 2008 2:09 am

Hey OT. I'm pretty much saturated with noise here. I more or less live with it.
It is sometimes better and sometimes worse. There are a few things I could try but I haven't done them. I have only so much time mess with this and a lot of that time is spent building. One of the problems is that AM band has been mixed or fairly poor ALL winter.Decent signals will usually be ABOVE the noise (on a good day). The winter of '06 to '07 was much better (go figure, we went BACKWARDS in the solar cycle THIS winter ).

I tried running the Icom off batteries and got a LITTLE relief. I could mess with magnetic or other isolation balun type schemes. I also have a phaser but building a good second "noise" antenna would be hard. I'm kind of stuck with the single longwire I have. K

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Re: VLF ant

Post by oldtimer on Thu Apr 24, 2008 1:05 am

Sounds tuff. You could always move to a more rural area. I'm in the center of Denver but the prw lines are in the alley. Also, my house is 1 blk from a very large city park. Lots of trees no major pwr lines. Very old residential. My long wire will be al least 45 deg from the lines. 2 parts, semi - balanced. So unless you are wired into this address, move out! OT

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Re: VLF ant

Post by krystallo on Thu Apr 24, 2008 6:07 pm

Hey OT.
No moving out possible, I'm pretty much "stuck" there for a number of reasons. I'll deal with it when I can as I can. I also go out on DXpeditions to the beach or forest and always get clean signals there.

K

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Re: VLF ant

Post by oldtimer on Thu Apr 24, 2008 11:35 pm

If there's a SAQ xmission this summer I might head to the eastern plains to pick it up. I'll have to camp out on a farmer's or rancher's land to do so to be away from noise. Grimeton Radio likes to rcv reports. Being at mile high it may be a good location. OT

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Re: VLF ant

Post by krystallo on Sun Apr 27, 2008 4:46 am

Hey OT.I'm thinking about a Palomar upconverter for VLf to HF for (hopefully) better copy of future SAQ' transmisssions. K

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VLF

Post by oldtimer on Tue Apr 29, 2008 11:44 pm

Hey, krystallo. Good deal. What sort of antenns(s) will you be using? Since I'm on the mailing list for Grimeton I suppose I'll rcv notice abt next b'cast.OT

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