[Lowfer] New vertical Y antenna

Bill Ashlock ashlockw at hotmail.com
Mon Dec 19 20:36:17 EST 2011 

Hi Jay,

The upper Y is made of of three #12 wires, each 34ft long. There are three parallel #18ga fill-in wires between each leg making it look like a spider web, from below. The lower Y is about 25% larger and has four #18ga fill-in wires. Neat how you can't even see these fill-in wires from any reasonable distance so they don't obstruct the new view of the 4000 ft mountains from the house.

The antenna floats relative to the ground and there is no ground connection on the 'antenna' side of the output transformer. The transmitter itself is grounded via the two input connections (DC power and coax coming from the exciter). There IS, however approx 1500pf of capacity between the lower Y and a 'test' ground stake below the transmitter. I'm thinking that the lower Y (or counterpoise) works so well because it makes a 'uniform' low resistance connection to the ground via the capacitive reactance of these planes. IE: the return current from the antenna is spread out equally over a large area. Might in fact behave as an near-infinite number of ground rods. Ten ground rods for example would have a non-uniform resistive connection to ground and some points would have a high current and have high I^2 R losses.

The Rac of my first vertical up here without counterpoise (5 years ago?) had an Rac of something like 500 ohms!

I'll get that "fire" going ASAP! Will let you know if NOT operational by tomorrow at this time. Let me know of any additional tests you would like me to run before the big snows arrive. Right now we have only about an inch on the ground, but it's been COLD!

Bill



> From: jrusgrove at comcast.net
> To: lowfer at mailman.qth.net
> Date: Mon, 19 Dec 2011 19:46:12 -0500
> Subject: Re: [Lowfer] New vertical Y antenna
> 
> Bill
> 
> Interesting. A couple questions ...
> 
> What are the dimensions of the Y?
> 
> Is the entire lower Y, loading coil and all connections floating above ground? Input side of 
> transformer as well?
> 
> Think you had a vertical up there before with 'conventional' ground system ... what was the R of 
> that antenna?
> 
> Please advise when you get some fire in the wire so I can have a look!
> 
> Jay W1VD  WD2XNS  WE2XGR/2
> 
> 
> 
> ----- Original Message ----- 
> From: "Bill Ashlock" <ashlockw at hotmail.com>
> To: <lowfer at mailman.qth.net>
> Sent: Monday, December 19, 2011 7:35 PM
> Subject: Re: [Lowfer] New vertical Y antenna
> 
> 
> >
> > Rick and group,
> >
> > I finally loaded up the antenna just before dark tonight after finding yet another bad connection 
> > in the RG-6 cable (now over 250ft long in order to reach the final at the base of the antenna). 
> > I'm seeing just about a watt of DC input power to the xmitter when I resonate the antenna by 
> > varying the exciter's frequency inside the shack. With a reduction of 11 to 4 in the transmitter's 
> > output transformer (Vcc = 22v), and with a little math, that works out to an Rac total of approx 
> > 10 ohms. I'm using a 'test' loading coil having an Rac of 5 ohms so the antenna itself has a loss 
> > of only 5 ohms!
> >
> > Should be able to make the final tune-up of the loading coil at 185.300 in the AM tomorrow... so 
> > look for my usual "Wm"s .
> >
> > Bill
> >
> > From: ashlockw at hotmail.com
> > To: lowfer at mailman.qth.net
> > Subject: RE: [Lowfer] New vertical Y antenna
> > Date: Thu, 15 Dec 2011 14:17:07 -0500
> >
> >
> >
> >
> >
> >
> >
> > Hi Rick,
> >
> > Yah, the progress has been good because the weather has been above normal lately... and almost no 
> > snow. Today, however, is the exception with freezing rain. I'm working inside modifying the one 
> > Xmitter I have up here, so it will drive a vertical. I'm starting with a 10 to 4 step-down ratio 
> > on the output transformer. That's figuring approx 10 ohm Rac total for the whole antenna (coil + 
> > gnd loss). The temporary loading coil I'm using has #18ga (equiv) Litz on it but the final, 
> > heavier, one has #12ga (equiv) Litz and wound interwoven for very low loss.
> >
> > Looking forward to receiving a return picture of the signal!
> >
> > Bill
> >
> >> From: smokinggun at verizon.net
> >> To: lowfer at mailman.qth.net
> >> Date: Thu, 15 Dec 2011 02:45:34 +0000
> >> Subject: Re: [Lowfer] New vertical Y antenna
> >>
> >> Bill,
> >>  Wow you work fast! Thats a lot of wire to put up in that short time. I
> >> cant wait to see the results. I think I still have a capture or 2 from  last
> >> season  and my receive setup hasnt changed.
> >>  Of course once you perfect the new antenna , I will bombard you with
> >> questions. Not that Im giving up the loop anytime soon.Its working too well
> >> for me right now.
> >> BTW; thanks for the "Y" formula..
> >>
> >>               Rick
> >>
> >>
> >>
> >>
> >>
> >> ----- Original Message ----- 
> >> From: "Bill Ashlock" <ashlockw at hotmail.com>
> >> To: <lowfer at mailman.qth.net>
> >> Sent: Wednesday, December 14, 2011 1:36 AM
> >> Subject: [Lowfer] New vertical Y antenna
> >>
> >>
> >> >
> >> > Rick and others,
> >> >
> >> > I'm all set to begin on-air testing of this new antenna once I install the
> >> > loading coil and transmitter at the base and run wires to it. The capacity
> >> > measurements between upper and lower "Ys" (plus fill-in wires) are
> >> > complete and I'm seeing approx 400pf between them. This makes for a low
> >> > Rac in the loading coil because of the relatively low inductance of 185mh
> >> > at 185.3KHz.
> >> >
> >> > Turned out there was quite a large-sized finge field from the top "Y" and
> >> > I had to expand the lower "Y" in order to capture a good percentage of it.
> >> > That rule of thumb saying the radius of the ground radials must be at
> >> > least equal to the height of the antenna proved to be true, BUT I think
> >> > this applies to a vertical WITHOUT top hat. When a top hat is used it
> >> > appears the radius must be equal to the antenna height PLUS the radius of
> >> > the top hat. At any rate it will be interesting to see how the total Rac
> >> > for this antenna comes out when I apply power, but I suspect it will be
> >> > very low if I have captured as much of the fringe field as capacity
> >> > measurements indicate. BTW there's a formula I found for the capacity
> >> > between two circular conductive planes separated by a large distance (like
> >> > 50ft) that seems to work. For Lowfer antennas it comes out approx 3 times
> >> > the capacity derived from the formula that is typically given in text
> >> > books for closely spaced planes not accounting for th
> >> > e fringe field off to the side. It's a bit lengthy but if anyone is
> >> > interested, I'll post it.
> >> >
> >> > Bill
> >> >
> >> >
> >> >
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