[amsat-bb] Re: Homebrew Elk-style 14/435 mhz log periodic for sats?

Edward Cole kl7uw at acsalaska.net
Fri Apr 17 22:50:29 PDT 2009 

Just to add some observations that support yours.

I started 12 years ago with a 2m yagi supported on 15-foot mast in 
the yard with 45-foot forest surrounding my property.  Working 2m SSB 
stations 60-70 miles away was a hit and miss, sometimes event 
(running 150w).  I built a 40-foot tower and mounted two 10-element 
yagis made from parts of a Cushcraft 20T satellite antenna and signal 
came up 3 s-units.  Then I put up my antennas ten feet higher and 
gained another 15-dB.  Of course the antennas were then above the tree line.

On the other hand, my father wanted a low impact TV antenna at his 
home in Michigan, so I suggested putting it up in the rafters of his 
ranch-style single story home.  I had just spent a summer in bush 
Alaska putting up TV translator systems with antennas mounted inside 
plywood shelters (on hill tops).  My dad's antenna was set up in the 
rafters of the garage.  It did better than I would have expected 
getting a good signal on VHF and UHF from TV stations 35-50 miles 
away.  19-years later the antenna is still there working.  They do 
have Direct-TV dish so have more choices, now.

Point is there is more than one way to make things work...if you 
understand the principles and limitations.  Short coax and hand-held 
antennas work pretty well, but not very convenient in some 
weather.  Longer coax runs and permanent antenna need a preamp to 
work best.  Getting the antenna clear of obstructions always is 
helpful, but if you are satisfied with working only at higher 
elevation angles then simple low antennas still work.

A full az-el CP yagi with preamp and auto-tracking is superb.  A 
simple short yagi fixed at 15 to 30 degrees and rotated in azimuth 
only works too.  Can you guess how well my L-band uplink will work 
with a 16-foot dish and 300w?  He he, well only for Oscar-zero.

73, Ed - KL7UW

At 07:52 PM 4/17/2009, n3tl at bellsouth.net wrote:
>Hey Bill,
>
>Your comments about construction, location, etc., are right one, 
>based on my experiences here. I actually move from one side of the 
>house to the other depending on whether passes are to my east or west.
>
>A couple of other things affect the performance I'm getting, too. 
>One of the most important is that my decision to continue using a 
>handheld antenna means I have less than six feet of coax from the 
>radio to the antenna. I'm still getting some loss, but not nearly as 
>much as I'd get by putting antennas in the attic and running much 
>longer feed lines to them. Another is a little trick K4DLG in 
>Florida passed along to me a while back.
>
>He has a log periodic for HF, and the coax runs from the antenna 
>feedpoint along the main boom to the back of the antenna before 
>heading down to the shack. Taking that lead, he did the same thing 
>with the Elk he bought. Doing so mitigated any significant changes 
>in SWR due to moving the antenna around while hand-holding it during 
>a pass. I tried it here and have observed the same thing. For me, at 
>this location (inside or out), 8 degrees of elevation was the best I 
>could hope for with the Arrow I had. In all the months I used that 
>antenna, I made only a few contacts when a given satellite was below 
>8 degrees here. When I started using the Elk, that "bottom line" 
>immediately dropped to 4 degrees. And when I tried K4DLG's 
>suggestion of running the feedline parallel to the boom, the 4 
>degrees dropped to 3.
>
>And, as you point out, depending on the location and relative path 
>of a given pass, I can work even lower and make contacts, as I have 
>with some stations in Europe on AO-7.
>
>All of that being said, I also still lose the satellites due to 
>obstruction, as you have observed with your Arrow. When it comes to 
>the FM LEO satellites, only the ISS transmits back to us using more 
>than milliwatt power levels. I know that AO-51 is capable of 1 watt 
>or more, but it generally is not configured to transmit at those 
>levels. Drew or someone, please correct me if that statement is 
>inaccurate. The published stats on AO-27 report a nominal output of 
>500 mW, and SO-50 is reported to operate with a nominal 250 mW 
>output. I believe both of them also use quarter-wave vertical 
>antennas, which are 0-gain.
>
>Given those power levels, it doesn't take much to begin affecting 
>reception, especially for handheld stations. From here at my home, 
>that quarter of azimuth from 90 degrees to 180 degrees is my worst. 
>For really consistent reception in that part of the sky, I need 
>upwards of 30 degrees elevation when I'm standing outside at ground 
>level. On the second floor of the house, I get reception good enough 
>to facilitate contacts with about 15 degrees of elevation at 
>azimuths from 90 degrees to about 130. I still need close to 30 from 
>azimuth 130 to 180 no matter where I try to operate from - in the 
>yard or upstairs.
>
>I hope you're able to come up with a solution for your location that 
>works even better than you expect!
>
>73 to all,
>
>Tim - N3TL
>
>
>-------------- Original message from Bill Dzurilla 
><billdz.geo at yahoo.com>: --------------
>
>
> >
> > Tim,
> > Yes, your QSO with F2IL is becoming famous, congrats. I think the 
> performance of indoor antennas must be heavily dependent on the 
> location of the shack and the construction materials used on the 
> house. I moved my Eggbeater and ground plane to the attic from 
> outside and noticed a sharp drop in performance. Also tried the 
> Arrow here inside the shack and it did not do too well. And noticed 
> that, even outside in the yard with the Arrow, I lose the sats at 
> low elevation, when they drop below the level of nearby roof lines. 
> On my DXpeditions to Swan Island and Jamaica, where there was 
> unobstructed view over the ocean, I could easily make contacts with 
> less than 1 degree of elevation with the same HT and
> > Arrow.
> >
> > 73, Bill NZ5N
> >
> >
> > --- On Fri, 4/17/09, n3tl at bellsouth.net wrote:
> >
> > > From: n3tl at bellsouth.net > Subject: Re: [amsat-bb] Re: Homebrew 
> Elk-style 14/435 mhz log periodic for
> > sats?
> > > To: "Joe" , billdz.geo at yahoo.com
> > > Cc: amsat-bb at amsat.org
> > > Date: Friday, April 17, 2009, 10:19 PM
> > > Bill and all,
> > >
> > > Joe is right. F2IL gave me a 569 report on AO-7 Mode B
> > > Thursday evening - and I was hand-holding my Elk on the
> > > second floor of my house, pointing it to the northeast at a
> > > spot on a windowless wall. When we worked, AO-7 was at
> > > roughly 3.5 degrees elevation here.
> > >
> > > I wish I had decided to try these low-angle passes months
> > > ago!
> > >
> > > 73 to all,
> > >
> > > Tim - N3TL
> > > -------------- Original message from Joe
> > > : --------------
> > >
> > >
> > > > You'd be amazed at what you can do with an indoor
> > > yagi also..
> > > >
> > > > My first 2 meter ant was a 3 ele quad on a photo
> > > tripod that sat right
> > > > next to me on the floor in the shack,
> > > >
> > > > Joe WB9SBD
> > > >
> > > > Bill Dzurilla wrote:
> > > > >Are there plans anywhere for a homebrew version of
> > > the Elk duo bander? After reading through the prior thread
> > > about the poor performance of Eggbeaters and other omnis,
> > > I'm ready to risk the wrath of my Homeowners Association
> > > and put up
> > > > a small beam.
> > > > >
> > > > >Or, anybody have an Elk for sale?
> > > > >
> > > > >73, Bill NZ5N
> > > > >
> > > > >
> > > > >
> > > > >_______________________________________________
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> > > > >
> > > > >
> > > > >
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