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- Date: Sat, 30 Apr 94 04:30:20 PDT
- From: Ham-Homebrew Mailing List and Newsgroup <ham-homebrew@ucsd.edu>
- Errors-To: Ham-Homebrew-Errors@UCSD.Edu
- Reply-To: Ham-Homebrew@UCSD.Edu
- Precedence: Bulk
- Subject: Ham-Homebrew Digest V94 #114
- To: Ham-Homebrew
-
-
- Ham-Homebrew Digest Sat, 30 Apr 94 Volume 94 : Issue 114
-
- Today's Topics:
- Adjusting vertical polarization of yagi
- digital RF Broadcasts
- TEK RADIO.....where?
- Vertical yagi mounting
-
- Send Replies or notes for publication to: <Ham-Homebrew@UCSD.Edu>
- Send subscription requests to: <Ham-Homebrew-REQUEST@UCSD.Edu>
- Problems you can't solve otherwise to brian@ucsd.edu.
-
- Archives of past issues of the Ham-Homebrew Digest are available
- (by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew".
-
- We trust that readers are intelligent enough to realize that all text
- herein consists of personal comments and does not represent the official
- policies or positions of any party. Your mileage may vary. So there.
- ----------------------------------------------------------------------
-
- Date: Fri, 29 Apr 1994 14:57:56 GMT
- From: ihnp4.ucsd.edu!swrinde!elroy.jpl.nasa.gov!netline-fddi.jpl.nasa.gov!nntp-server.caltech.edu!news.claremont.edu!paris.ics.uci.edu!csulb.edu!csus.edu!netcom.com!dgf@network.ucsd.edu
- Subject: Adjusting vertical polarization of yagi
- To: ham-homebrew@ucsd.edu
-
- In article <phb.767566512@melpar> you write:
- > In a recent on-the-air discussion, I pointed out the error
- >of mounting a two-meter yagi in the vertically-polarized
- >
- >3) Has anyone out there ever purposely installed a yagi array
- >vertically using a metal mast and tried to measure the effects
- >(VSWR, azimuthal pattern accuracy, etc.)? I have a A148-10S
- >which is currently mounted horizontally, and have been toying
- >with rotating it into the vertical plane and trying to measure
- >the effects, but maybe someone else has tried it out of
- >scientific curiosity.....
- >
- >
-
- I'm posting this because e-mail to you bounced.
-
- When I mounted my Cushcraft 15 element 2M yagi on the center of my mast
- in vertical polarization, I arranged it so the person at the top of the tower
- could adjust the axial rotation (of the boom) while I monitored SWR at the
- bottom of the tower (thru about 60' of RG213). The bottom line is the SWR
- went way up (over 2:1) within 10 degrees of true vertical, and we settled
- on about 20 degrees off vertical (favoring the orientation that improved
- drainage away from the balun box) which minimized SWR (not the absolute
- minimum, but I accepted a 1.3:1 as OK).
-
- In this situation, I get about 10 dB gain *over* a diamond 10 foot gain vertical
- which is mounted about 10 feet higher on the tower (at the very top of the
- mast). Everything is operating about as expected (the diamond has about 6-7
- dB of gain on it's own, and the beam appears to have about 10 dB more gain in
- it's favored direction).
-
- I did not measure "directivity" or any other factor in the straight-vertical
- orientation, because the higher SWR was disabling my brick at the bottom of
- the tower.
-
- I hope this helps.
-
- 73 Dave WB0GAZ dgf@netcom.com
-
- ------------------------------
-
- Date: Thu, 28 Apr 1994 12:58:52 GMT
- From: ihnp4.ucsd.edu!swrinde!sgiblab!wetware!spunky.RedBrick.COM!psinntp!psinntp!arrl.org!zlau@network.ucsd.edu
- Subject: digital RF Broadcasts
- To: ham-homebrew@ucsd.edu
-
- yctcsl@cerfnet.com wrote:
-
- : Need info on sending digital message over RF broadcast of 3 mi radius or less.
- : Like to keep FCC restrictions to a minimum if possible. Message size 8bytes or
- : less. Terrain varies in area of use. need freq that handles obtstruction well.
-
- I'm certainly not a regulatory expert, but my experience is that
- very low frequencies tend to handle obstructions the best. The
- Navy uses them to communicate with submarines. I've actually
- heard VLF signals through our solid metal screen room walls.
- (it isn't designed to stop such low frequencies). But, generating
- strong signals generally requires large antennas and high data
- rates are usually considered impossible. Noise at VLF can also
- be a big problem. But, if you want signals to go through water,
- concrete, and steel, consider frequencies below 30 kHz.
-
-
- --
- Zack Lau KH6CP/1 2 way QRP WAS
- 8 States on 10 GHz
- Internet: zlau@arrl.org 10 grids on 2304 MHz
-
- ------------------------------
-
- Date: Fri, 29 Apr 94 07:04:20 MST
- From: ihnp4.ucsd.edu!swrinde!gatech!udel!pacs.sunbelt.net!lynx.unm.edu!dns1.NMSU.Edu!dns1.NMSU.Edu!usenet@network.ucsd.edu
- Subject: TEK RADIO.....where?
- To: ham-homebrew@ucsd.edu
-
- On Wed, 27 Apr 1994 14:10:15 GMT,
- Richard Kowalsky <cmdorat@tc.fluke.COM> wrote:
-
- >Hi, I have heard about a small dedicated data radio called the
- >"TEK" radio. It supposidly supports 9600 baud packet. I would
- >like to get my mits on one unfortunately, every one I ask just says
- >that "they are advertized in QST, look in there."
-
- Richard they are TEKK Inc. radios and we are using one for the university
- packet node to get from mountain top to the Internet Gateway on campus. It
- works ok, but it was a mess to get the deviation setup (you will neeed some
- good test eq.- we used HP specctrum and a telemetery receiver). Their
- address is 226 NM Parkway, Kansas City, MO. 64150 phone 1-800-521-tekk and
- fax 816-746-1093. Hope that helps. 73 Bill
-
- ------------------------------
-
- Date: Fri, 29 Apr 1994 12:46:32 GMT
- From: newsgate.melpar.esys.com!melpar!phb@uunet.uu.net
- Subject: Vertical yagi mounting
- To: ham-homebrew@ucsd.edu
-
- A couple of followup comment from the original poster:
-
- > One of the on-the-air participants, admittedly a new ham,
- >became very defensive and said that he used a Cushcraft
- >A147-11 vertically polarized on a metal mast, and his antenna
- >"had directivity."
-
- NOTE: My on-the-air comments did not suggest the antenna
- had "no directivity", only a screwed-up pattern, but the
- "defensive" ham took it that way.....
-
- >pattern off by creating either more than one lobe or skewing
- >the main lobe above or below the plane of the array by some
-
- Poor choice of words; "above or below the plane of the array"
- implies the antenna is horizontal when it isn't; what I mean
- here is that the major lobe no longer points in the same direction
- the antenna is pointed because of the deleterious effect of the
- metal mast, which is now parallel to the parasitic directors and
- has a detuning effect.
-
- (|_|) * Paul H. Bock, Jr. K4MSG * Internet: pbock@melpar.esys.com
- | |) * Senior Systems Engineer * Telephone: (703) 560-5000 x2062
-
- "You can have my bug when you can pry my cold, dead fingers from
- around it....." - anonymous radiotelegraph operator
-
- ------------------------------
-
- End of Ham-Homebrew Digest V94 #114
- ******************************
-