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- Date: Thu, 3 Feb 94 09:11:29 PST
- From: Info-Hams Mailing List and Newsgroup <info-hams@ucsd.edu>
- Errors-To: Info-Hams-Errors@UCSD.Edu
- Reply-To: Info-Hams@UCSD.Edu
- Precedence: Bulk
- Subject: Info-Hams Digest V94 #108
- To: Info-Hams
-
-
- Info-Hams Digest Thu, 3 Feb 94 Volume 94 : Issue 108
-
- Today's Topics:
- Boring WWV Programs
- Dayton Parking: Hell on Earth!
- Field Day Logging Program
- Freebies from ARRL HQ
- Help - your Vertical Ant. experences.
- Kenwood TS940 pll-car unlock....HELP!
- RAC FORUM QUESTIONNAIRE
- RAMSEY FX TRANSCEIVER (2 msgs)
- Rtty Dx Notes
- WWCR 5.810MHZ 8pm 12pm Eastern(CHECK IT OUT!!)
- Your experiences on 40 meter CW QRP
-
- Send Replies or notes for publication to: <Info-Hams@UCSD.Edu>
- Send subscription requests to: <Info-Hams-REQUEST@UCSD.Edu>
- Problems you can't solve otherwise to brian@ucsd.edu.
-
- Archives of past issues of the Info-Hams Digest are available
- (by FTP only) from UCSD.Edu in directory "mailarchives/info-hams".
-
- 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: Mon, 31 Jan 1994 20:43:20 GMT
- From: metro!news.cs.su.oz.au!harbinger.cc.monash.edu.au!yeshua.marcam.com!news.kei.com!eff!news.umbc.edu!europa.eng.gtefsd.com!library.ucla.edu!news.ucdavis.edu!chip.ucdavis.@munnari.oz.au
- Subject: Boring WWV Programs
- To: info-hams@ucsd.edu
-
- ARMOND@delphi.com wrote:
- : Those WWV people are not nice at all. I was just trying to be helpful
- : when I called to tell them that my S-38 (which I got at a swapmeet
- : for $15) inmdicated that WWV was about 10 kilocycles off. That, when
- : they were not drifting. I suggested they go to crystal control.
- : I got this really neat Timex watch at a yard sale for $5. It sez that
- : ] WWV is about 30 seconds off. What snotty people work at WWV. They did
- : not appreciate my helpful call at all.
-
- Perhaps you should have used the telephone instead of calling them on
- frequency. BTW: yopu were 59 in No. Cal
- ;-)
-
- --
- *---------------------------------------------------------------------*
- * Daniel D. Todd Packet: KC6UUD@KE6LW.#nocal.ca.usa *
- * Internet: ddtodd@ucdavis.edu *
- * Snail Mail: 1750 Hanover #102 *
- * Davis CA 95616 *
- *---------------------------------------------------------------------*
- * I do not speak for the University of California.... *
- * and it sure as hell doesn't speak for me!! *
- *---------------------------------------------------------------------*
-
-
- ------------------------------
-
- Date: 3 Feb 94 13:56:18 GMT
- From: news-mail-gateway@ucsd.edu
- Subject: Dayton Parking: Hell on Earth!
- To: info-hams@ucsd.edu
-
- >They're going to use the money saved to print up nice award certificates
- >for all the hams who earn WAS while trapped in the traffic jam. :-)
-
- yeah, but Gary, the Dayton guys always seemed to have trouble getting
- organized on mass transit. maybe they should 'qsy' to some place that can
- handle large crowds routinely -- say Orlando....not that the OARC would
- approve...8)
-
- of course, maybe we should just get everyone organized to park at the mall --
- "economic turmoil reigns! Salem Mall closed by invading hordes of radio
- hams...McDonalds makes emergency deliveries to restaurant after the entire
- food supplies were consumed by the horde..Noble Romans reported improved sales
- reached 'sluggish' levels over the weekend..residents report lamps glowing
- with power turned off, wavy lines on their TVs and strange thumping out of
- stereo and radio speakers..young children frightened..strange vehicles roaming
- the streets -- could they be operators of cat detector vans? are your cat
- licenses up to date? is it the end of the world? is Elvis there?"
-
- maybe the hamfest should be at the mall...any old NCR warehouses unused? and
- has anyone found a use for the old Western Electric plant in Indianapolis?
- That place even has a very large parking lot AND a huge amount of space under
- cover and an International Airport that's on an Interstate and easy to get in
- and out of (unless Dayton's changed a bunch..)
-
- maybe dayton needs another big event around september/october so having a
- large parking area at the Hara Arena would be more practical -- maybe the
- arena could be leased out to the Tonya Harding Physical Therapy Center for
- Injured Skaters.
-
- Dayton may have had the "natural" for a large convention and has certainly
- worked to get this spot as the "big one", but maybe it's ripe for plucking
- given the constraints forced upon them by the area.
-
- bill wb9ivr
-
- ------------------------------
-
- Date: 3 Feb 94 13:55:40 GMT
- From: news-mail-gateway@ucsd.edu
- Subject: Field Day Logging Program
- To: info-hams@ucsd.edu
-
- Hello,
-
- Well it's time to start planning for Field Day. It's my job
- to find a good logging program. So I am looking for suggestions
- and opinions and will summarize the responses in case anyone else
- is doing the same.
- Please e-mail direct to me.
-
- Thanks and 73
-
- Tom, kv2x
-
- --
- -------------------------------------------------------------
- |
- Thomas J. Jennings | Tel: (716) 273 7071
- Development Engineer | Fax: (716) 273 7262
- |
- ABB Process Automation |
- Post Office Box 22685 |
- Rochester, New York 14692-2685 |
- |
- -------------------------------------------------------------
- Internet: jennings@jennings.rochny.uspra.abb.com
- -------------------------------------------------------------
-
- ------------------------------
-
- Date: Tue, 1 Feb 1994 18:44:48 GMT
- From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!news.intercon.com!psinntp!psinntp!psinntp!arrl.org!lhurder@network.ucsd.edu
- Subject: Freebies from ARRL HQ
- To: info-hams@ucsd.edu
-
- A reminder to all that the American Radio Relay League
- continues to make available to Amateur Radio Operators and
- non-amateurs alike a wide variety of free materials and
- services. Of particular interest to the not-yet-licensed
- individual would be the ARRL Prospective Ham Package. In
- the PHP, one would find:
- -
- 1. Printouts of Volunteer Examination session
- opportunities in his/her area.
- -
- 2. Listings of Amateur Radio clubs in his location.
- -
- 3. Helpful promotional material about the Amateur Radio
- Service.
- -
- The already-licensed individual might well be interested
- in another free ARRL publication, the ARRL Public Service
- Communications Manual. The PSCM represents the "bible" of
- public service communications, and clearly/concisely
- points out how the ARRL National Traffic System and the
- ARRL Amateur Radio Emergency Service function as a
- cohesive unit to provide the maximum support to the public
- both in times of disaster as well as "normal" times.
- -
- To obtain these free ARRL services, please
- provide me with:
- -
- A. Your name
- B. Your mailing address
- C. A Specific request for either of the two services
- (the PHP or the PSCM) mentioned above.
- -
- 73!
- -
-
-
- | | | Deputy Manager, Field Services, ARRL.
- | |___| The ARRL Amateur Radio Emergency Service, the ARRL
- | uck | |urder National Traffic System, The Amateur Auxiliary to
- ------ | | the FCC's Field Operations Bureau, the ARRL
- KY1T Field Organization and the ARRL Monitoring System.
- ----------------------------------------------------------------------------
- lhurder@arrl.org Prodigy - MGTS39A, BIX - ARRL,
- MCI Mail - RPALM, MCI Mail - "ARRL", America On Line - "ARRL HQ"
- Compuserve - 70007,3373 (ARRL HQ) -- Genie ARRL.HQ
-
- ------------------------------
-
- Date: 31 Jan 1994 20:53:21 GMT
- From: metro!news.cs.su.oz.au!harbinger.cc.monash.edu.au!yeshua.marcam.com!news.kei.com!eff!news.umbc.edu!europa.eng.gtefsd.com!howland.reston.ans.net!cs.utexas.edu!news.tamu@munnari.oz.au
- Subject: Help - your Vertical Ant. experences.
- To: info-hams@ucsd.edu
-
- >is one of the best all band verticals around. Don't know too much about the
- >others but the R5 is a vertical dipole and as such does not have as much gain
- >as a quarter wave gound plane or similar antenna. Note the Butternut as well
-
- Probably depends on where in the pattern you are, can't think of any
- inherent reason for a quarter wave ground plane to have more gain than a
- vertical dipole. If I understand what is meant by a quarter wave ground
- plane its a 1/2 wavelength antenna but the bottom leg(s) are not in the same
- plane as the upper.
-
- Greg Taylor, KD4HZ // g-taylor4@tamu.edu // 409-845-4445 // Fax-847-8744
-
-
- ------------------------------
-
- Date: 1 Feb 94 21:14:59 GMT
- From: mvb.saic.com!connected.com!news.sprintlink.net!nic.hookup.net!paladin.american.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!aries!hawley@network.ucsd.edu
- Subject: Kenwood TS940 pll-car unlock....HELP!
- To: info-hams@ucsd.edu
-
- My TS940 (1987 vintage) unlocks during warmup, receive (or xmit) goes away
- and a half second later the display goes to all dots. This lasts for a blink
- to a few seconds each time, and happens zero to a half dozen times only during
- warmup from cold which takes 5 or so minutes.
- I have done the following:
- 1. Inspected the PLL, CAR, and DIG A board for solder breaks...nothing obvious.
- 2. Flexed (lightly), cooled, and resoldered many connections on these boards.
- 3. Inspected the VR board and resoldered this and that.
- 4. Observed no power supply voltage changes during the unlock on these boards.
- 5. Observed the unlock signal occuring during the problem, but was unable to
- tell which pll chip was sending it first.
- During all of this extreme invasion of the 940's guts, the characteristics of
- the unlocking during warmup has not changed one bit. Makes me think I'm on the
- wrong boards.
- I've also checked all the peaking up, and setting of vco ranges on the pll and
- car boards according to many suggestions and bulletins. R100 on the pll board
- was not the problem, as once reported here on the net.
- Is there any particular coil that has been troublesome, or some other part
- perhaps that anyone knows about?
- The problem goes away during the summer months.
- Help.
-
-
- ------------------------------
-
- Date: Mon, 31 Jan 1994 07:33:35
- From: unogate!news.service.uci.edu!usc!howland.reston.ans.net!usenet.ins.cwru.edu!eff!news.kei.com!yeshua.marcam.com!zip.eecs.umich.edu!destroyer!nntp.cs.ubc.ca!alberta!adec23!@mvb.saic.com
- Subject: RAC FORUM QUESTIONNAIRE
- To: info-hams@ucsd.edu
-
- Bid: 7604_VE6YYC
- From: VE6AFO@VE6YYC.#CGY.AB.CAN.NA
- To : RACONV@CANADA
-
- RAC Forum Questionnaire
-
- The First National Convention of Radio Amateurs of Canada will
- provide an excellent opportunity for amateurs to meet face to face
- with the directors of RAC and discuss issues that will help to
- shape the direction of amateur radio in Canada. This questionnaire
- is designed to help the RAC directors get a feel for the basic
- issues. The RAC Forum will provide the opportunity for these and
- other issues from the floor to be addressed as well.
-
- Please check the appropriate line to signify your assessment of
- RAC's handling of the listed issues. Space is also provided if
- you wish to make any specific comments. For any additional
- comments or concerns please use a separate sheet.
-
-
- Poor Fair Avg Good Don't
- Know
-
-
-
- The RAC Central Incoming QSL Bureau __ __ __ __ __
-
-
-
- The RAC Central Outgoing Bureau __ __ __ __ __
-
-
-
- The Provincial Incoming QSL Bureaus __ __ __ __ __
- (please state province)
-
-
- The Canadian Amateur magazine __ __ __ __ __
-
-
-
- Regulations and legal issues __ __ __ __ __
-
-
-
- Tower issues __ __ __ __ __
-
-
- Licensing __ __ __ __ __
-
-
-
- EMC issues (TRC-86) __ __ __ __ __
-
-
-
- Membership __ __ __ __ __
-
-
-
- Headquarters and Administration __ __ __ __ __
-
-
-
- Spectrum issues and band planning __ __ __ __ __
-
-
-
- Services to members __ __ __ __ __
-
-
-
- Field Services Organization __ __ __ __ __
-
-
-
- RAC Bookstore __ __ __ __ __
-
-
-
- Attracting new people
- to the ham community __ __ __ __ __
-
-
-
- Attracting new members to RAC __ __ __ __ __
-
-
-
- Club affiliation with RAC __ __ __ __ __
- (your thoughts please)
-
-
-
- Are you a member of RAC? YES __ NO __
-
-
-
- Please submit either on packet radio to Ken VE6AFO @ VE6YYC or mail
- to: Ken Oelke VE6AFO, 7136-Temple Drive N.E., Calgary, Ab., T1Y 4E7
-
- ------------------------------
-
- Date: 31 Jan 94 08:42:58 GMT
- From: netcomsv!netcomsv!cruzio!comix!jeffl@decwrl.dec.com
- Subject: RAMSEY FX TRANSCEIVER
- To: info-hams@ucsd.edu
-
- In article <9401281134.A4225wk@support.com> steven.rosenberg@support.com writes:
- >
- >So you're saying they DO work if assembled correctly...
- Sure. There were some synthesizer spurs that were fixed with
- judicious grounding. The VHF receiver sensitivity wasn't fabulous
- (approx .40uv/12db SINAD). The transmitter would oscillate badly
- when mistuned. Two kits arrived dead and left working. I'm
- not going to claim that they were fabulous performers. Nor were
- they stable over a wide range of temperature or power supply voltages.
- However, they do operate. I didn't see anything "illegal"
- or dangerous in the operation or design. Again, I do NOT
- consider the radio a superior or state of the art product.
- If it had a dual gate GAsFET front end, high level mixer,
- helical resonators thruout, dual PLL tx/rx local oscillators
- for fast TR switching, fewer tx spurs, tracking filter rx
- front end, built in PL, RS-232 control, ad nausium..., I would
- consider it state of the art. Is there some other kit manufacturer
- other than Ramsey that has a superior product?
-
- >>a while, I drag my Cushman CE-6 service monitor to the repeater
- >>site and call out tx frequency and deviation for everyone checking
- >You are a prince among hams! This would be a great service for all such
- >capable amateurs and local clubs to offer. It's a great way to ensure
- >that all those FM transmitters are operating properly. Again, I commend
- >you.
-
- I've received 4 pieces of email indicating that this would be
- a good thing to do. All it would take is making friends with
- your friendly local 2way shop. I've noticed a trend over the
- last 25 years. The hams and the commercial operators appear
- to barely tolerate each other. 25 years ago, every two way tech
- was a ham. Now days, the techs with ham licences ask me not
- to mention that they work for a commercial shop. One local ham
- needed a commercial radio programmed for ham frequencies. This
- proved to be a major political challenge.
-
- My pilgrimage to the local repeater site (5 minutes from my office)
- is not much of a challenge. I do it whenever I find the excuse.
- However, 50 check-ins followed by 20 arguements does not encourge
- repetition. What I ask is that they check in normally. If the
- deviation is low, I ask them to YELL into the microphone. This
- shows if the deviation setting is low or if the tx audio gain is
- low. I have to explain the difference between the audio/mic gain
- and deviation at least 10 times. The process has lasted as long
- as 3 hours. Many hams will check in with every radio they own
- causing me to get confused. The same hams check in with the
- same screwed up radios every time. Little wonder the commercial
- shops don't want to spend the time and effort.
-
- At the last Winterfest in Montery CA, the KM6DZ group used the
- latest greatest HP service monitor to check handhelds and mobiles
- for anyone interested. Most everything was measured. Next year,
- the box will probably be HPIB (IEEE488) computer controlled so that
- it can be done automatically. Many of the brand new radios were
- miserably adjusted. In spite of the large number of handhelds
- in evidence, only about 50 radios were checked. It makes me wonder
- if the others even cared.
-
- It's not too difficult to turn your repeater receiver into a piece
- of test equipment. Here's some ideas:
-
- 1. Instant replay. Install a speech recorder that records the last
- 10 seconds of a transmission. If someone wants a signal report, they
- can hear themselves and judge for themselves.
-
- 2. You can measure SINAD remotely. Modulate the rx local oscillator
- of the repeater to +/- 3.0Khz deviation at 1.0Khz. Notch out the
- 1.0 Khz tone at the repeater audio with a commutating synchronous
- filter. The ratio of the audio before and after the filter is
- proportional to the SINAD. If you want to go high tech DSP, read
- the June 1993 issue of QEX for a program to do it with a TI320C25
- DSP chip.
-
- 3. Measure frequency remotely. Many repeater controllers (RLC-1)
- have A/D converters suitable for measuring the discriminator
- voltage. Some have remote offset calibration functions for dealing
- with adjustments and drift. Have the repeater belch the frequency
- error.
-
- 4. There are still a bunch of tunable PL encoders in use. Our
- repeater K6BJ returns a differnet courtesy tone depending upon
- whether the PL decoder hears the correct tone. Just tune till
- the tone changes.
-
- You don't need a service monitor to get things right. It helps,
- it's nice, but it's not necessary. Your repeater can do the job
- adequately with some construction. If it works, turn it into a
- kit and sell it.
-
-
- --
- # Jeff Liebermann Box 272 1540 Jackson Ave Ben Lomond CA 95005
- # 408.336.2558 voice wb6ssy@ki6eh.#nocal.ca.usa wb6ssy.ampr.org [44.4.18.10]
- # 408.699.0483 digital_pager 73557,2074 cis [don't]
- # jeffl@comix.santa-cruz.ca.us scruz.ucsc.edu!comix!jeffl
-
- ------------------------------
-
- Date: Tue, 1 Feb 1994 20:18:54 GMT
- From: mvb.saic.com!unogate!news.service.uci.edu!usc!elroy.jpl.nasa.gov!newncar!csn!col.hp.com!srgenprp!alanb@network.ucsd.edu
- Subject: RAMSEY FX TRANSCEIVER
- To: info-hams@ucsd.edu
-
- Greg Bullough (greg@netcom.com) wrote:
- : In article <CKIEMA.KCq@srgenprp.sr.hp.com> alanb@sr.hp.com (Alan Bloom) writes:
- : >... I wish QST had MORE construction articles, not fewer. ...
-
- : I agree, but I also believe that the construction articles have
- : to be carefully targeted, and within reach. I'd also like to
- : see articles on older gear, both generic and specific, that with
- : some wrenching, tuning, and tweaking, can be made more serviceable
- : for the average newcomer.
-
- : Call them 're-construction' articles. :-)
-
- 20 or 30 years ago, when military surplus was plentiful, there were lots
- of articles in the ham rags about how to convert military gear for ham use.
- There were also many articles on how to modify commercial amateur
- gear: "Add a Product Detector to a 75A2 Receiver" "A Q-Multiplier for
- the HQ-110" "Convert Your Command Set Into an SSB Exciter" etc. Not many
- amateurs built complete stations from scratch even then, but most did at
- least some surplus conversion or modifications to commercial gear.
-
- I agree with you that QST should do at least occasional articles of that
- genre. Some years ago, QST virtually banned tube-based construction
- articles (other than high-power RF amplifiers), and I suppose that's
- all to the good. But there's a lot of older tube-type gear out there
- that sells for a song. With a little modification, those old clunkers
- could have a lot of life left in them.
-
- For example, how about a digital readout that could be configured to
- work with most any transceiver/transmitter/receiver? (With modification
- instructions for several of the most-popular older rigs?) How about
- a synthesized external VFO? If it covered the 5 - 5.5 MHz (or so) range
- it would work with many older radios. I wish I had the time to work on
- some of those projects! Anybody else have more ambition than I?
-
- AL N1AL
-
- ------------------------------
-
- Date: 1 Feb 1994 20:25:04 GMT
- From: mvb.saic.com!unogate!news.service.uci.edu!usc!cs.utexas.edu!swrinde!emory!news-feed-1.peachnet.edu!concert!inxs.concert.net!rock.concert.net!mikewood@network.ucsd.edu
- Subject: Rtty Dx Notes
- To: info-hams@ucsd.edu
-
- In article <Angelo_Glorioso_Iii.2mmf@agwbbs.new-orleans.LA.US>,
- Angelo Glorioso Iii <Angelo_Glorioso_Iii@agwbbs.new-orleans.LA.US> wrote:
- >VK2SG DX NOTES 28 JAN 94
- >
- >S.M.O.M. 1A0KM. After three years a group of operators will be on from
- >Jan. 26 to 31 on CW/SSB and RTTY on all bands but no 160. Qsl via
- >I0IJ.(No report on the Cluster anyway up to now). MOUNT ATHOS. Monk
- >Apollo, has been quite active recently on 20, 80 and 40 SSB. Keep
- >fingers crossed for a return also to RTTY.
- >
- >
-
- Did anyone any where actually work or even hear this Dxpedition?
-
- Nothing at all was reported in S.E. USA.
-
- Thanks, Mike / NT4O
-
-
-
- Mike Wood Internet: mikewood@rock.concert.net
- The Signal Group
- P.O. Box 1979 ***Avoid company disclaimers by owning the company ***
- Wake Forest, NC 27588
-
- Phone: 919-556-8477 Fax: 919-556-0115
-
- ------------------------------
-
- Date: 1 Feb 1994 20:28:12 GMT
- From: mvb.saic.com!unogate!news.service.uci.edu!usc!howland.reston.ans.net!usenet.ins.cwru.edu!cleveland.Freenet.Edu!eb795@network.ucsd.edu
- Subject: WWCR 5.810MHZ 8pm 12pm Eastern(CHECK IT OUT!!)
- To: info-hams@ucsd.edu
-
- But socialism is a way to enslave people, do you think it is not?
- --
- Eric Matthews
- eb795@cleveland.freenet.edu
-
- ------------------------------
-
- Date: Mon, 31 Jan 1994 13:55:16 GMT
- From: pacbell.com!sgiblab!swrinde!cs.utexas.edu!howland.reston.ans.net!usenet.ins.cwru.edu!ukma!rsg1.er.usgs.gov!junger@network.ucsd.edu
- Subject: Your experiences on 40 meter CW QRP
- To: info-hams@ucsd.edu
-
- In article <2ie8ki$2ih@clarknet.clark.net>,
- Andrew M. Cohn <andy@clark.net> wrote:
- >If you work 40 meter CW, with 5 watts or less, and use less than ideal
- >antennas (no beams, dipoles or rhombics, etc), I would like to hear about
- >your experiences. No...I'm not writing a book; I just want to know what
- >I can expect before investing in a QRP station!
- >
- >Many thanks & 73,
- >Andy, K4ADL
- >andy@clark.net
- >
-
- The key for me in working 40 CW successfully (and I'm not all that
- successful!!) is having a good receiver and listening carefully
- and diligently. Band conditions seem to vary quickly and drastically
- on 40; you should be able to recognize when it is a good time to work
- hard for DX and when you just might as well rag chew with the guy
- down the street. I wouldn't (and don't) use any antenna that was
- "worse" then a resonant dipole in performance. You might consider
- some of the "shortened" dipoles if space is a factor; but I don't
- have any experience with them.
-
- BTW, I use 100W; I'm not bored enough to try QRP yet..... I believe
- that most successful QRP operators have spent lots of time working
- with "normal" rigs before they go to QRP. At least that's the
- impression that I have.
-
- cheers -- John, W3GOI
-
- ------------------------------
-
- Date: 2 Feb 94 04:14:50 GMT
- From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!cis.ohio-state.edu!news.sei.cmu.edu!toads.pgh.pa.us!w2xo!durham@network.ucsd.edu
- To: info-hams@ucsd.edu
-
- References <1994Jan27.134222.1@tntvax>, <2ibe9h$6lk@cascade.ens.tek.com>, <gtaylor.315.0@taex003n.tamu.edu>s.acs.oh
- Subject : Re: Help - your Vertical Ant. experences.
-
- In article <gtaylor.315.0@taex003n.tamu.edu> gtaylor@taex003n.tamu.edu (Gregory S. Taylor) writes:
-
- >>others but the R5 is a vertical dipole and as such does not have as much gain
- >>as a quarter wave gound plane or similar antenna. Note the Butternut as well
- >
- >Probably depends on where in the pattern you are, can't think of any
- >inherent reason for a quarter wave ground plane to have more gain than a
- >vertical dipole. If I understand what is meant by a quarter wave ground
-
- If you are really interested in the relative gains, etc, of various
- lengths of vertical radiators, you can get a copy of the FCC
- rules and regs for AM broadcast stations. This used to be available
- for a very small sum from the government printing office. In it
- is a chart showing the field strengths developed by various lengths
- of vertical radiators. You will see that a quarter wave vertical
- does *not* have more gain than a half wave, actually less. The signal
- strength continues to increase as the length of the radiator is
- increased and tops out at 5/8 wavelength..hence the popularity of
- the 5/8 for 2 meter mobile work.
-
- Also at work here is the fact that a 1/2 wave radiator has a
- very high driving impedance. Consider the antenna and
- ground to be in series, like two resistors. If the
- ground connection is high impedance,like when you have
- no radials, then, if the antenna is low impedance (1/4 wave),
- most of the energy is dissapated in the ground connection..
- not at all what you want. However, if the antenna is
- high impedance (1/2/wave), then a much larger part of the
- RF is consumed in the antenna, which is what you want.
-
- It's still probably a good idea to ground even a half wave
- vertical. It won't hurt and probably will help. Otherwise
- you're depending on the capacitance of the coax feedline
- to act as a ground and then there's the lightning thing...
-
- One note concerning ground plane antennas. They don't work
- as "ground plane" antennas until they are sufficiently high
- that the RF field from the antenna flows more in the ground
- plane wires than in dirt. If it is too low, you get severe
- losses from a quarter wave ground plane. This can be overcome
- by increasing the number of ground radials. THe FCC used to
- require 120 radials to achieve proper efficency when the vertical
- was right on the ground. When it's higher, then you need fewer.
- Since the half wave antenna has mostly voltage at the bottom
- and not current (high impedance), then the RF field is highest
- at the middle of the antenna and does not flow in the ground
- so much..ergo, the efficiency is higher when ground mounted..unless
- you want to put 120 radials on the 1/4 wave!
-
- Hope this helps..
-
- Jim, W2XO
-
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- End of Info-Hams Digest V94 #108
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