[600MRG] More 630m antenna efficiency...
Gedas
w8bya at mchsi.com
Sun Sep 2 09:45:58 EDT 2018
IMO the absolute cheapest, accurate, and efficient way to get wires way
up high and exactly where you need them is with a "wrist-rocket" type
sling shot....sometimes known as a hunting sling-shot.
You can find them on Amazon etc for ~$15 shipped. You can get very fancy
with all kinds of other excellent devices but if you want fast and cheap
and where ya want it in the tree just get one and be done in no time.
I reel out about 100' of fishing line on the ground in a long zig-zag
(back-and-forth) pattern, attach a 1-2 ounce tear-drop shaped fishing
sinker to the end of the fishing line, stand off and behind and away
from the fishing line on the ground then let-er-rip. Even in areas that
have tall grass etc the line on the ground will work fine. Just make
sure it is not wrapped around any branches or debris on the ground that
will keep the fishing line from being pulled up and into the air.
The sinker will be over the limb you need in 3-4 seconds along with your
initial fishing line. If it does not fall to the ground just LEAVE
EVERYTHING BE for an hour or so and nature (slight breeze and branch
motion) will let gravity slowly drop the sinker to the ground for you.
I then go to the far end of the line that is now on the ground, break
off the sinker, and tie on one end of a 300' roll of 1/8" white Nylon
twine. You can get 200-300 feet of this stuff for less then $6......pull
it up and in place of the fishing line and now you are ready to attach
your real Dacron rope etc to the 1/8" Nylon twine. Done in no time with
a total of ~$20 spent. And no fear of an arrow breaking free and coming
down or through someplace you did not want it to 300' away. At least
that's the way I do it here. Been doing it this way for over 45 years
and it works 100% of the time for trees up to 80' or so.
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 9/2/2018 9:21 AM, Dwight Blevins via 600MRG wrote:
> Dave,
>
> Sounds like our situations are similar. Dirt here in western Colorado
> is mix of sandstone and ground glass. With about 5 to 6 inches of
> precip per annual, might as well forget the verticals, though I do
> have one. Couple of 40 ft. tall trees in the back yard, so I'm trying
> to figure out how to get a wire up and over without breaking my 72
> year old neck.
>
> Anybody ever tried casting a fishing line? Probably a bow would work
> best, but I've never had to use this sort of thing to get a wire over
> a tree top. No way to get a bucket truck back there, so I'm still
> scratching my head on how to get my wires up higher, at least on one
> or two sides of the loop. After reading all the comments on ground
> loss the past couple of days I'm convinced more effort with the
> vertical is probably a bad idea.
>
> Time is flying by, with only a few weeks to go before 630m fall activity.
>
> Ike, KW7T
>
> On Sunday, September 2, 2018, 3:32:34 AM MDT, Dave Riley
> <dave.riley3 at verizon.net> wrote:
>
>
> Aye, Pat,
>
> The possibilities become endless with new technology but I still
> struggle with a self imposed beer budget left over from that great
> depression...
> Mainly because it is cheap, fun, and really taxes my mojo or what is
> left of any creative juices...
>
> If one is blessed or cursed with high pines trees then nirvana is
> either here or gone...
>
> A compound bow, air gun, or sling shot is the new and cheaper bucket
> truck with dacron rope so strong and cheap that it doesn't even get
> recycled...
>
> The latest attempt here at cheating nature is to rig wires and feed
> till the DX goes up... I'm always harping on groundless antennas cuz
> let's face it, that's where most power is lost...
> Trillions of idle radials can't be wrong...
> Sixr inch copper strap makes a wunnerful loop for efficiency until the
> breeze comes up then the copper goes airbourne and another
> disappointment needs to be forgotten...
>
> Today's new scientific observations suggest that a loop of wire
> suspended within the pine tree opening says that if the bottom of the
> loop ( horizontal wire ) wire rests upon the ground that the BW of the
> loop goes way up and so do the losses...
> Raising the bottom wire just a few feet above the ground narrows
> bandwidth and losses significantly... So today I will spend hoisting
> the bottom wire of this loop to about 10' off the ground and see what
> those numbers say...
>
> Ground conductivity here on the BC band is between poor and rotten and
> is mostly silica sand... So I imagine an efficient loop in 'free
> space', but that is not the case as yet...
>
> After today there is one remaining try at reducing 'ground losses' and
> hopefully that will not be a secret by sundown... After that, back to
> microwave like wire antenna modeling for seniors... 50 mhz. seems best
> for model building/scaling...
>
> Maybe skydiving is next...
>
> 73s de Dave, still stuck in reality...
>
>
> On 9/1/2018 11:02 PM, patrick hamel wrote:
> Impractical??
> When I was a novice someone gave me an old (1930 vintage) Handbook
> including wooden lattice tower construction.
> A 100 foot lattice tower with cross arms and side ropes to hold the
> loop in shape is possible.
> If you have the room and money for the tower you might be able to
> afford rigid (threaded) aluminium conduit for the radiator (it does
> exist). Today we have various plastics which would make a lattice
> tower long-lasting instead of the treat-it-yourself wood (barrel of
> creosote) I remember being discussed. Today we have bucket trucks for
> tree-trimmers and construction cranes that could make erection of such
> a tower a safe and practical.
> 73,
> Pat W5THT
>
>
> ------------------------------------------------------------------------
> *From: *"J Mcvey via 600MRG" <600mrg at mailman.qth.net>
> <mailto:600mrg at mailman.qth.net>
> *To: *600mrg at mailman.qth.net <mailto:600mrg at mailman.qth.net>, "Dave
> Riley" <dave.riley3 at verizon.net> <mailto:dave.riley3 at verizon.net>
> *Sent: *Saturday, September 1, 2018 9:23:33 AM
> *Subject: *Re: [600MRG] More 630m antenna efficiency...
>
> I played with the loop calculator at the link that you provided.
>
> Got some impractical results:
> diameter 90.5 feet ( I used a length of 300 ft which was in the range
> they suggested)
> conductor 0.9 inch
> Q= 497 !!!!
> BW = 1.27 KHZ
> Cap voltage = 5000 volts RMS
>
> Even with a conductor almost 1 inch in diameter , the Q is 497 and the
> BW is 1200 HZ
> 1) 90.5 foot diameter ? how does one build and install such a structure?
> 2) How does one tune ( and keep tuned) something with a Q of 497?
> Servos with continuous feedback?
>
> I thought the whole thing was "loopy"
> On Saturday, September 1, 2018, 9:37:42 AM EDT, Dave Riley
> <dave.riley3 at verizon.net> <mailto:dave.riley3 at verizon.net> wrote:
>
>
> It's fun to see the banter and playback all around... Termination of
> this discussion ended up around 1.65/1 SWR, ( self written results ) ...
> Brain food, that's all it is, and maybe a good antenna...
>
> Now for the next batch of toil and trubble to wrestle over...
>
> I am a confirmed loopest and have sworn NEVER to divert ANY RF in to a
> lossy ground system... EVER...
> To that end I promise to keep all power possible in the LOOP, as it
> were... Enuf of it gets lost in the ground as it stands already...
>
> The next personal challenge here is to arrive at the possible EIRP
> from this loop, 5W eirp for the very least RF power input...
> Right now it is costing me about 13 watts in order to claim 5W eirp +/-...
>
> I started out with a monster dog wire loop 630m antenna made from
> e-bay for very cheap $$ and I was astounded by how simple a single
> wire antenna on our new band could perform...
> I only added a good vacuum variable cap. in series and used a good mix
> for the Ferrite coupling transformer...
>
> I use this small loop transmit formula which may or may not be the
> best bottom line in computation...
> http://www.66pacific.com/calculators/small-transmitting-loop-antenna-calculator.aspx
>
> I am now at the stage of trying to increase the wire diameter from #14
> stranded copper to something larger for cheap money and lots of gain,
> say 1/4"...
>
> Here is what I have up now:
> 450' circumference loop, using double CATV RG6a coax with a copper
> runner...
> https://www.ebay.com/itm/Directv-Dual-Black-CR03BDR0-05-Ground-RG6-Coax-Cable-on-EnviroReel-ReeLogic-Reel/163202369537?hash=item25ff9e8801:g:WRgAAOSwc2FaLfFs
>
> It is lightweight, contains 5 separate conductors, and when paralelled
> together must add up to something more than .25" diameter or so...
> Maybe today I will measure say 25' of each wire on the RF bridge and
> report back...
> Below is a 'rac' table taken from Bill Ashlock's work as my starting
> point of reference;
>
> We read in the book of Bill's, the efforts derived from the following;
> ConductorType Rac ohms Tot Rac ohms
> #12 awg 1.15 1.37/1.48 0.83/.80 0 db ** Reference
> start point...
> #10 awg 0.92 1.14/1.25 0.91/.87 +0.8 db
> #8 awg 0.72 .92/1.03 1.02/.96 +1.8 db
> #6 awg 0.57 .79/.90 1.09/1.03 +2.4 db
> #4 awg 0.45 .68/.79 1.18/1.10 +3.1 db
> #2 awg 0.36 .57/.68 1.29/1.18 +3.8 db
>
> #12 x 4 0.32 .55/.66 1.31/1.20 +4.0 db
> #12 Litz 0.57 .79/.90 1.10/1.03 +2.4 db
> #12 Litz x 2 0.30 .59/.70 1.27/1.16 +3.7 db
> #12 Litz x 4 0.16 .38/.49 1.58/1.39 +5.6 db
> RG-8/11 0.38 .60/.71 1.26/1.16 +3.6 db
> ½” Cu pipe 0.15 .37/.48 1.60/1.41 5.7 db **** BEST by
> far LOWEST a.c. 'R' measured
>
> This table is based on Bill Ashlock's testing @ 185kc. and a 200'
> circumference square loop... 50' on a side...
>
> My question now is what will the RAC be of the 5 separate RG6A
> conductors wired together in parallel??? I guess @ .4" equivalent
> diameter +/- for;
> Antenna efficiency: 34% (-4.7 dB below 100%)
> Antenna bandwidth: 2.07 kHz
> Tuning Capacitance: 622 pF
>
> Capacitor voltage: 1,573 volts RMS
> Resonant circulating current: 2.92 A
> Radiation resistance: 0.402 ohms
> Loss Resistance: 0.772 ohms
> Inductance: 181 microhenrys
> Inductive Reactance: 539 ohms
> Quality Factor (Q): 230
> Distributed capacity: 369 pF
>
> Antenna "circumference": 450 feet
>
> That is with one copper wire carrier, two solid shields of 75 ohm
> coax. approx .240" each, and two center conductors ( copper ) #18 or so...
>
> It is very tempting to go to Lowe's and buy 10' sections of 3/4"
> schedule 'M' copper pipe!!! Am resisting...
> It is already too easy to make 5W eirp from the low power transverter
> here... Why re-invent the wheel??
>
> Comments??
>
>
>
> ______________________________________________________________
> 600MRG mailing list
> Home: http://mailman.qth.net/mailman/listinfo/600mrg
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:600MRG at mailman.qth.net <mailto:600MRG at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> 600MRG mailing list
> Home: http://mailman.qth.net/mailman/listinfo/600mrg
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:600MRG at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> 600MRG mailing list
> Home: http://mailman.qth.net/mailman/listinfo/600mrg
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:600MRG at mailman.qth.net <mailto:600MRG at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> 600MRG mailing list
> Home: http://mailman.qth.net/mailman/listinfo/600mrg
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:600MRG at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/600mrg/attachments/20180902/7cfb2f53/attachment.html>
More information about the 600MRG
mailing list