Date: Fri, 22 Apr 94 04:30:10 PDT From: Ham-Ant Mailing List and Newsgroup Errors-To: Ham-Ant-Errors@UCSD.Edu Reply-To: Ham-Ant@UCSD.Edu Precedence: Bulk Subject: Ham-Ant Digest V94 #115 To: Ham-Ant Ham-Ant Digest Fri, 22 Apr 94 Volume 94 : Issue 115 Today's Topics: 2m/70cm on a Honda.. Which One? 2m Amplifier mounted at antenna? 70cm Parabolic Dish Power (?) noise in antenna Yagi Formulas Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Ant Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant". 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: Wed, 20 Apr 1994 23:36:38 GMT From: ihnp4.ucsd.edu!agate!news.ossi.com!news.fai.com!amdahl!juts.ccc.amdahl.com!p1dbg02!dws30@network.ucsd.edu Subject: 2m/70cm on a Honda.. Which One? To: ham-ant@ucsd.edu Rumor has is keying up with some rigs will kill the computer in the car. I would like to know if this would be a problem with a 89 Accord. I would also like to know what 2m/70cm antenna and mounting seems to work the best. I have a FT-530 and will most likely pick up a moble, so if you have any helpfull hints on those I am very interested in that info as well. 73 - -------------------------------------------------------------------------- Dave Sharpe Sunnyvale Ca. DWS30@duts.ccc.amdahl.com -------------------------------------------------------------------------- ------------------------------ Date: 20 Apr 94 09:06:10 CDT From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!vixen.cso.uiuc.edu!uchinews!cdsmail!timbuk.cray.com!walter.cray.com!ned.cray.com!cbetz@network.ucsd.edu Subject: 2m Amplifier mounted at antenna? To: ham-ant@ucsd.edu In article <2ou099$kap@taco.cc.ncsu.edu>, nsyslaw@riogrande.acs.ncsu.edu (Lou Williams) writes: > I was curious if anyone here has tried using a 2m amplifier > mounted at the antenna, instead of at the rig. Most installations > I've seen have them mounted with short patch cables aft of the > rig, but in my case the feedline is over 100' and I was curious > if it would perform better / no-difference when mounted nearer > to the antenna? (The power would be switched in/out with the > rig. I've seen too many instances of amplifiers gone astray > and sending splatter/interference all over the band, so I DON't > wish to leave it on all the time). > > I realize that the feedline drop will be a drop going into the > amplifier vs having the amplifier output dropped because of > the feedline. What I've never seen is a comparison of which > method performs better. I think perhaps the biggest problem is the voltage drop you'll experience on the power cables to the amp, unless you are running a rather small amp which only draws an amp or two of current. If for example, you are running a 10 watt in, 170 watt out brick, the brick will be drawing around 25 - 30 amps an the 12 volt supply lines. Unless you are going to mount the power supply at the antenna also (probably not real practical), you'd better run some pretty hefty power cables out to the amp. Otherwise, you are going to experience some significant voltage drop to the amp. Charlie Betz N0AKC ------------------------------ Date: 20 Apr 94 09:11:08 CDT From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!uchinews!cdsmail!timbuk.cray.com!walter.cray.com!ned.cray.com!cbetz@network.ucsd.edu Subject: 70cm Parabolic Dish To: ham-ant@ucsd.edu In article <1994Apr15.224452.18046@gov.nt.ca>, ve8ev@gov.nt.ca (John Boudreau) writes: > > Is it worthwhile to try to use a 2.5m parabolic dish for 70cm? > I have a surplus TVRO dish and would use a 3 turn helix as a feed. > If so, what would be the smallest practical size for the reflector > on the helix to maximize the gain while blocking the least amount > of signal from the dish. Also, what sort of gain could I expect? > It would be used for 70cm EME and also for satellite work. > > A 2.5m (10 ft.) dish is too small for 70cm EME. This size dish is generally considered the minimum size for 1296 MHZ EME. Charlie Betz N0AKC ------------------------------ Date: 21 Apr 94 13:52:42 GMT From: sdd.hp.com!vixen.cso.uiuc.edu!ux2.cso.uiuc.edu!ignacy@hplabs.hp.com Subject: Power (?) noise in antenna To: ham-ant@ucsd.edu Lately my 2x10m dipole picks up a S7-9 noise on all bands. This noise is steady and sometimes can be cut out by noise blanker but not always. The noise disappears late night and reappears at 8-9 am. Nothing at home seems to generate it. In particular, a few feet of wire in the house as the antenna picks no noise. One side of the antenna is about 6ft to the power lines, so I thought that the noise is coming from them. However, my HT does does not pick up anything. An AM portable radio finds buzzes close to power cords. It has found a loud buzz (similar to that in my radio) at one HV pole, about 200 ft from my yard. I am unsure what to do. If this is a power noise, why it disappears at night? Is condensation suppressing sparks at some power insulator? I have handi-finder to find a noise with the HT, but since HT does not pick up anything, nothing can be found. I could ask the power company to come and investigate that HV pole. However, if they don't find anything, they will ignore my later calls. Any ideas? Ignacy Misztal Ham radio: NO9E, SP8FWB E-mail: ignacy@uiuc.edu University Of Illinois 1207 W. Gregory Dr., Urbana, IL 61801, USA tel. (217) 244-3164 Fax: (217) 333-8286 ------------------------------ Date: 20 Apr 1994 08:11:29 -0700 From: get.hooked.net!news.sprintlink.net!connected.com!seatimes.seatimes.com!seatimes.seatimes.com!not-for-mail@decwrl.dec.com Subject: Yagi Formulas To: ham-ant@ucsd.edu You will find a nice write up in the ARRL Handbook (at least the '94 edition) regarding spacing of elements on Yagi antennas. There is a corrospondance between seperation of elements and the lengths of the reflector, directors, and driven elements. For general purposes though, the seperation between elements should be on the order of .15 - .25 wavelength. The .25 figure seems to be more forgiving of slight errors in element length and provides for a little more broadening of the bandwidth. ------------------------------ End of Ham-Ant Digest V94 #115 ******************************