Date: Fri, 24 Dec 93 04:30:14 PST 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 V93 #152 To: Ham-Ant Ham-Ant Digest Fri, 24 Dec 93 Volume 93 : Issue 152 Today's Topics: 2M from 11M Question. 6m antenna help (3 msgs) Annonymous FTP Ham Sites? Antenna Tuner Questions Better Gain antenna for HT? Hustler Mobile as Base Antenna The ant farm Vertical Antenna Question (3 msgs) 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: Thu, 23 Dec 1993 15:10:19 GMT From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!news.intercon.com!udel!news.sprintlink.net!direct!news.direct.net!kg7bk@network.ucsd.edu Subject: 2M from 11M Question. To: ham-ant@ucsd.edu Brian Pollack (wizkid@indirect.com) wrote: : (And is it a good idea, assuming a magmount 11M is very cheap : and at every hamfest.) -Brian KB7TSY Hi Brian, It will probably be lossy on 2m. The coax is lossy and the 3/8" mount is lossy on vhf. Your word "cheap" describes it well. However, it would probably work better than a rubber duck inside the car. MFJ has a dual band mobile vhf/uhf mag mount antenna for $15 which is inexpensive and is probably better than 11m stuff. 73, Cecil, kg7bk@indirect.com Queen Creek, AZ ------------------------------ Date: 22 Dec 1993 13:59:38 GMT From: ucsnews!sol.ctr.columbia.edu!math.ohio-state.edu!mane.cgrg.ohio-state.edu!aus1.robins.af.mil!wrdis02.robins.af.mil!gwood@network.ucsd.edu Subject: 6m antenna help To: ham-ant@ucsd.edu need help on building a 6m quad 2,3,4, elelmen for use on packet ssb,fm,am if any one can help me with a good book or design it would just great. -- KC4YBL GREG WOOD EM82 ------------------------------ Date: 22 Dec 1993 13:55:41 GMT From: ucsnews!sol.ctr.columbia.edu!math.ohio-state.edu!mane.cgrg.ohio-state.edu!aus1.robins.af.mil!wrdis02.robins.af.mil!gwood@network.ucsd.edu Subject: 6m antenna help To: ham-ant@ucsd.edu need help on building a 6m quad about 2,3,4, element as long as i has a good 9,8 db or higher i would like to be able to us it on ssb,packet,am ,fm,.if anyone out there can help me out with a good book or design. -- GREG WOOD kc4ybl em82 ------------------------------ Date: 22 Dec 1993 15:46:33 GMT From: ucsnews!sol.ctr.columbia.edu!math.ohio-state.edu!mane.cgrg.ohio-state.edu!aus1.robins.af.mil!wrdis02.robins.af.mil!gwood@network.ucsd.edu Subject: 6m antenna help To: ham-ant@ucsd.edu i would like to get some help on building a 6m quad for packet,fm,ssb,am,cw i would like it have at least 3,4,5 elements any books that might help or a design would be a big help -- GREG WOOD kc4ybl em82 ------------------------------ Date: 23 Dec 93 11:27:13 GMT From: ogicse!psgrain!news.clark.edu!pacifier!ronh@network.ucsd.edu Subject: Annonymous FTP Ham Sites? To: ham-ant@ucsd.edu I amm looking for a few good clues to your favorite, and best Anonymous FTP sites for Ham and SW programs. Working on my ticket, and like to collect Radio programs, antenna programs and the like. Please send reply E-Mail, as my news server glitches from time to time. Thanks much in advance! Happy holidays to all!! Ron Hays :wq ------------------------------ Date: Wed, 22 Dec 93 09:39:14 CST From: library.ucla.edu!agate!iat.holonet.net!vulcan!gary@network.ucsd.edu Subject: Antenna Tuner Questions To: ham-ant@ucsd.edu alanb@sr.hp.com (Alan Bloom) writes: > Cecil Moore (kg7bk@indirect.com) wrote: > > : I need the equations governing the > : transfer function of a voltage and/or current balun that is not arcing > : and/or saturating. I can't find them in W2FMI's book, Maxwell's book, or > : any of the ARRL publications that I own. Where the heck are they? > > Ideally, the transfer function for a 4:1 balun is R(load) = 4 * R(source) > and X(load) = 4 * X(source), assuming the load is connected to the > "4" side of the balun. > > Or perhaps you meant you want to calculate the power-handling capability > with high SWR. The easy answer to that question is to assume that a balun > designed for the amateur limit can handle 1.5 kW (plus some margin) into > a 50 ohm load. The worst-case voltage or current will be multiplied by > the square root of the SWR. (High-impedance loads increase the voltage, > low-Z loads increase the current.) > > The upshot of this is that, under worst-case conditions, the power > rating is degrated by a factor equal to SWR. For example, if the > SWR is 3:1, you can safely use your 1.5 kW balun at 500 watts > without arcing the windings or saturating the core. > > AL N1AL > Is the transfer function really this simple ? As a first-order estimate, I disagree. I think the balun has distributed R, L, G, & C and therefore looks like both a transmission line and a transformer. A good place to start (if you really want to chaaracterize a balun) would be the Fall 1992 Communications Quarterly. An article by Jerry Sevick discusses two different models for baluns. I think, though, that if you are wanting to derive a transfer function, you will have to go review some of the references cited in the article. I think that a transfer function will ultimately depend on the physical makeup of the balun of interest, as well as the frequency at which it is used. Good Luck. -- Gary Tennyson BellSouth Telecommunications, Inc. Internet: gary@vulcan.com ------------------------------ Date: Thu, 23 Dec 1993 17:56:12 GMT From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!vixen.cso.uiuc.edu!sdd.hp.com!col.hp.com!csn!boulder!dosstudent.Colorado.EDU!millerpe@network.ucsd.edu Subject: Better Gain antenna for HT? To: ham-ant@ucsd.edu I need suggestions for a HT antenna that has better that 1 dB gain and is still flexable. I am looking for a rubber-whip-type that is not longer than 20". Thanx in advance millerpe@spot.colorado.edu ------------------------------ Date: 23 Dec 1993 08:55:28 -0800 From: swrinde!gatech!howland.reston.ans.net!agate!library.ucla.edu!news.mic.ucla.edu!unixg.ubc.ca!nntp.cs.ubc.ca!cyber2.cyberstore.ca!vanbc.wimsey.com!vanbc.wimsey.com!not-for-mail@network.ucsd. Subject: Hustler Mobile as Base Antenna To: ham-ant@ucsd.edu In article , Victor Tavernini wrote: >I happen to have a Hustler mobile antenna and a 40 meter resonator ... >and was wondering ... is it possible to use it as a base anteenna? You could, but the efficiency of the antenna is probably less than 10% of a dipole. > >If so, would I need to add radials? The more the better, but it may also shift the resonance frequency of the antenna a little. 73 & Seasons Greetings de VE7MDL ....Erik. > >Thanks, > >Victor Tavernini >Racal-Datacom, Inc. > >tavernin@sun1.interlan.com ------------------------------ Date: 14 Dec 93 01:16:50 GMT From: dog.ee.lbl.gov!agate!howland.reston.ans.net!sol.ctr.columbia.edu!usenet.ucs.indiana.edu!silver.ucs.indiana.edu!djadams@ucbvax.berkeley.edu Subject: The ant farm To: ham-ant@ucsd.edu Greetings! Has anone used the MB-2a from the ant farm...sounds a bit to too good to be true... 73 de Dave, N9UXU David J Adams, N9UXU Internet: djadams@silver.ucs.indiana.edu Amiga User and Flow Cytometry Advocate Looking for a mobile 2m and/or 70cm rig Conure Society of America. "Push the button Frank..." --- -. .-.. -.-- .- -- .. --. .- ------------------------------ Date: 23 Dec 93 18:53:04 GMT From: ogicse!uwm.edu!cs.utexas.edu!math.ohio-state.edu!darwin.sura.net!fconvx.ncifcrf.gov!mack@network.ucsd.edu Subject: Vertical Antenna Question To: ham-ant@ucsd.edu In article rlt@ssd.intel.com (Roger Traylor) writes: >I have a vertical antenna question. In most explainations of how >a typical vertical antenna works, a picture is shown of a 1/4 wave >vertical with its image projecting into the earth. (assuming ground >mounted antenna) I have a situation that would place my vertical >antenna directly over an irrigation well which is about 30 ft deep. >My frequency of interest here is 7Mhz. There is water in about the >last 15 feet of the well. > >My question is: If I can drop a ~30 foot wire down the well as the >1/4 wave image, will a substantial ground radial system still be >required? Would this work at all? > >Thanks, > >Roger Traylor There's a couple of things here - the image about from using an infinite ground plane. The 1/4wave radials are resonant and provide a choke to stop the current from going down the outside of the coax. They also act as the terminating point for the field lines originating in the vertical, so there deployment (angle to the vertical etc) affects impedance. Alsothe raidals need to be dense enough that the physical ground (the dirt) doesn't intercept the field lines and you don't heat up the dirt. Quarter wave radials act similarly to an infinite ground plane although comeone else will have to explain it - I don't understand that point. You wire down the well will not stop the currents going down the out- side of the coax and it will not prevent your power heating up the ground. It wou;d be better to lay your one radial along the ground (I think). However there is no requirement for your vertical to be above ground. I have read tht the military has thoughtor has done occassionally, buried their vertical downwards and used this to radiate. So you could have your usual radials and throw a wire down the well. There are some minor points that I don't remember like why you aren't heating up the dirt and how the signal gets above ground. I didn't pay much attention to this as I never thought I'd be making one. Joe NA3T mack@ncifcrf.gov ------------------------------ Date: Thu, 23 Dec 1993 16:37:54 GMT From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!sol.ctr.columbia.edu!news.kei.com!ssd.intel.com!rlt@network.ucsd.edu Subject: Vertical Antenna Question To: ham-ant@ucsd.edu I have a vertical antenna question. In most explainations of how a typical vertical antenna works, a picture is shown of a 1/4 wave vertical with its image projecting into the earth. (assuming ground mounted antenna) I have a situation that would place my vertical antenna directly over an irrigation well which is about 30 ft deep. My frequency of interest here is 7Mhz. There is water in about the last 15 feet of the well. My question is: If I can drop a ~30 foot wire down the well as the 1/4 wave image, will a substantial ground radial system still be required? Would this work at all? Thanks, Roger Traylor -- Roger Traylor rlt@ssd.intel.com Intel Corporation - Supercomputer Systems Division Beaverton, OR 97006 ------------------------------ Date: Thu, 23 Dec 1993 17:08:20 GMT From: swrinde!cs.utexas.edu!howland.reston.ans.net!gatech!usenet.ufl.edu!mlb.semi.harris.com!controls.ccd.harris.com!drs@network.ucsd.edu Subject: Vertical Antenna Question To: ham-ant@ucsd.edu Roger Traylor (rlt@ssd.intel.com) wrote: : I have a vertical antenna question. In most explainations of how : a typical vertical antenna works, a picture is shown of a 1/4 wave : vertical with its image projecting into the earth. (assuming ground : mounted antenna) I have a situation that would place my vertical : antenna directly over an irrigation well which is about 30 ft deep. : My frequency of interest here is 7Mhz. There is water in about the : last 15 feet of the well. : My question is: If I can drop a ~30 foot wire down the well as the : 1/4 wave image, will a substantial ground radial system still be : required? Would this work at all? Roger, I think you would end up with an antenna that is marginal at best. You will probably get some explanations from technical experts but from a practical aspect, either elevate the vertical from the ground as far as you can (example, I have a full size 40 meter ground plane 20' off the gnd). If you elevate it, your losses will diminish greatly. Otherwise, put down as many radials on the ground as you can. The more the better. I don't know of many more choices for a 1/4 wave vertical. 73's Doug, N4IJ : Thanks, : Roger Traylor : -- : Roger Traylor : rlt@ssd.intel.com : Intel Corporation - Supercomputer Systems Division : Beaverton, OR 97006 ------------------------------ End of Ham-Ant Digest V93 #152 ****************************** ******************************