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T.L.SI11_li.llTIA DI VI SI O]l
.Li.PHIL 1975_
President: R. E:1nett "111::710".:
Se~yg J. Golston VK?ZGJ, G.P .o. Box 1010, Launceston. 7250
~asy.ry,x:, J. Carter VI{?AK
Editorg B. Y0onan VK7'l,BY, c/- De}_)artment of Transport
Launceston Ji.irport, Tas~ 7250 Ph. 918218
won CE OJi' HEETETGS
I,IaJ'.:g 3rd Council Meeting, QT~I of VY:7ZBY Launceston J,irport, 2.00 p.r:T.
7th Sou thorn Branch, spoci.:.,l General Meetine, ({I'H of Tor:r Allen,
VK71Ji, 8 p.n.
9th Northern Branch, Civil Def011ee Building, "3ourke Street,
Lo,uncenton, 8 p.n.
13th Horth-Vlest Branch, Lakins r::~.11 Ulverstono, 8 p.n.
]:_DI TORJ J;L
Well Gentlonen, another J._nnual General Lieeting and Dinner lcas cone
and gone. It cannot be said that members attended both these functions
in force, in fact tho total nUI1bor of members that even bothered to fill
in their 1)allot papers, v1as to say the least, disappointine-. · I don't
k710v✓- uhGt the reasbns are for this ap1,arent lack of interest.in
Divisiunal matters, but it can do nothing but create dissatisfaction
ar,iongst the m0r.1b0rs ·J]w are trJinc to do their best to keep this Division
a vi1)rant and viablo oneo
I c,::,,11 on all nenbors of this Di vision to back their B::-::i,nches and
Divisional Council in all natters to enmlre that this year, \7ill be the
year vhon the VI:? Division becomes a united and active one.
73, Brian VICT7~DY
;11:1other Intelsat IV comnunications satellite - the sixth in the series,
and the second'to be placed over the Pacific - has been launched from
Cape Canaveral, Plori<la.
The satellite, clesignec1, and built by Hughes I..ir&raft Cor:ipany of
California, YTas launched by N .~~.So.A4 for the International Tele~
Comnunications Satellite Org·anisation. fill l'ctlas Cef1taur booster was
used to l)lace the satellite in synchronous orbit 35,300 kn. abov0 the
equator, ancl one dec-ree from the International Dateline.
The ne,, Intelsat IV 1:;rill provide added capacity and back-up assurance
for the prinary Pacific satelli to, launched in .January 1972. It YTill
become part of a 11 11eck=lacen of Intelsat IV' s orbiting the globe. Three of
these are over the ;,,tlc:mtic Ocean 1 ",1hilst another is over the Indian Ocean.
Reprint Electronics l1ustra1ia - March 1975
2.
REPORT ON 1975 J.1.NlITJAL GENEfulL HEETIHG
On Saturday the 5th of Ap:t'il the VICT A.G.M. was held at the A.E.B.'
Rooms, High Street, Launceston, with 34 members and one visitor present,
the visitor being Bill VI{3ZLK.
The meeting opened on time -.v.i. th Reg Emr:1ett VICTKK in the chair, and
Steve VICTOA, as secretary. li.fter the reports from br-th the President
and Treasurer -vvere presented, {a copy of the Treasurer's statement
appears at the end of this report) the natter of electing Divisional
Councillors for the ensuing year was carried out in the form of a ballot.
The result of that ballot is as follows:
1. VICTJi.K Bill Carter 5. VK7FB Mike J·emrer
2. VK.7IGC Reg Emmett; 6. VJ.CTZJ1Q Graeme Rand
3. VICTPF Peter Frith 7. VKTZBY Brian Yeoman
4. VK7ZGJ Joe Gelston
The election of other office-bearers then took place, and they are:
Patron: YICTAG J. Milne
QSL l\JTana,eer: VJ.CTCH c. ffarrison
Legal Officer: VICTRR · B. Morgan
Bulletin Editor: VICTZBY B. Yeoman
Key Section Co-Ordinator: VK7RH R. Harwood
Intruder Watch Co-Ordinator·: VK?!U: Il. Ivoa
Y.R.c.s. Supervisor: Vh'7KK R. Ebnett
Historical Officer: Council to take care of this in the
ensuing year, and to establish a
peruanent location.
VHF Representative: Vh'7ZGJ J. Gelston
Auditor: Council to handle
Oscar Co-Ordinator: VK?PF P. Frith
Membership Secretary: VICTZMK M. Ifuott
WIGEN Representative: VICTJV J. Van Staveren
h.fter these positions were filled, the meeting moved into the t\zo
motions on the agenda, as per the March Bulletin. The resul~ of these
motions were:
1. The raotion concerning constitutional amendments was passed with
no amendment.
2. The motion concerning the VJCT Merit ;~vrard was passed·with one (1)
amendment, that being that wherever the word "member" occurs, it
should be changed to 11 person 11 •
With the passing of tllaae wo motions the 1975 A.G.)II. closed at
1600 hrs.
A General Meeting of the VK7 Di vision folloued the Ji..G.M., and
started at 1610, -rd. th the follow:i.ng resolutions made with regard to the
laid down agenda.
1. On the subject of books and magazines at present held by the
Southern Branch; they are to be retained by the VJ.CT Division
and Council will assume care and control of the said books and
magazines.
3.,
/1.• G.I,1. REPORT (Contd. )
2. On the subject of equip1rent held by Branches - the Division is to
retain the 7I'Ihz transmitter and associated equi1x:1ent for broadcast
purposes, and that the renainder of the equi11r;10nt in the Southern
Branch becoue Southern Branch property with one amendLJent - that
should the 3outhern Branch uish to dis1)ose of this equipment, that
it be advertised as a 'render in the Di vision.al Bulletin.
3. The next i ter:; discussed was that of Branch L.GwM. uniforni ty. It
uas resolved tllatif Council recomDonds it, all Branch A.G.M~s Y.rill
be in Uarcl,.
4. In the area of discussion instigated by Branch Presidents, it
appeared that all Branches i.;ere qui to hap1w ui th the present
relationships between than and the Di vir3ion.
5. The Bulletin Editor gave n brief rundovm on the Bulletin C'.)Stine,
and stated that ,:;iroviding things rew:dned as they aro, the yearly
cost of the Bulletin should be around :GIOO. The Editor also· asked
for comnents from the menbers on tho })resent Bulletin fornat, bi-
monthly 1')osting, etc. as it is difficult to kno':1 ·what the members
are looking for in their Bulletin without feedback f:ronr them.
6. On the subject of broadcasts, members present o,t this meeting
r;2,ve a reassurance that they Y."ere quite hapi,y vi th the system as
it stands o,t present, and asked that the people concerned with the
Sunday aorning broadcasts vhether originating or re-brondcasting
be thanked for their efforts in the 110.st and the future.
7. There being no other business, the General Heeting closed at
1700 hours.
At ap:prox9 1930 hours the }..ru1uo.l Dirmer of the VK7 Division got
under \7ay at tJ:1e Villae;e I11otel Launcosfon ui th 44 persons attending.
A very enjoyable dim10r, which ,"~as ,:ashed dmm ',ri t:1 a - selection of
excellent di1mer .1in0s, uo.s vory suitably disposod of, and judgine by
0
the reactions and antics of sone :,embers, and thoiJ::- ,r.i ves :;;;resem.t, the
1975 Lnnual Dim-~0r '>:as n rip-roarinc success. ;rJ:1e only comments I have
to nake is to thank the or[;'anisorE1 for their efforts in ensuring that
the uhole shou, including the L.G.E. :,rogrossed sr10othly; those who
did not attend this narvellous dinner were the ones ,Tho missed out.
73, Brian VIC7ZDY
DLi'.LTEUE R:.DI0 EZ~IIBITI0H
The dates for the Lr!mteur Radio .E:xltihi tion at tl10 Northern Regional
Library in Launceston have beer: finalised. The exhibition is to be hold
frOi:l June 9 th to Juno 21s t inclusive.
rorn V1"0°WR, ·who is organising this display would aprireciate any
equi1-ir1ent that you feel \10uld ·bu ;:mi table for this oxhibi tion.
As the exhibition is to be set up on SatuTday the 7th June, the
deadline for the equipment will be the last ueek in Hay to give Norn
and his helpers time to see }1m7 the display is goine- to fit together.
For further details see your October Bulletin on this subject.
EDITOJ1
4.
Receipt1:1,
Balance Brought Forvmrd ,s; 336-63
Gene_ral .i1ccount Interest 15-36
·rerm:. Deposit Interest 78-00
Donations Life Members 44-00
Subscription Collections 66-00
Refunds Federal Executive _773-74
1313-73
petty Cash Sec. $ 5-00
Wreath 10-00
Convention Expenses '73 98-52
A.R. Inserts and Advertisements 24-44
A.R. Losses to VK3 116-00
Bulletin Eixpenses 102-28
7 W.I. Licences 12-00
Stamp Duty Con0titution 2-00
Refund Interest Southern Branch 234-00
Travelling Expenses S. Fraser 18-75
Share Surplus Funds N.W. Branch 38-00
Subscriptions to E.D.P. Re,. 66-00
Unpresei1ted Cheques as at 22/2/75 543-80
--42-94_
1313-73
-
Treasurer: s.u. Carter
Auditor: D.H. Fisher
Auditor's Note: Monies from Federal Executive not readily
reconcileable ,nth documents received, and have taken these as
presented.
Equipment lwcount stands at $28-00 and is to be transferred to the
General I~ccoun.t.
5.
IJE.i:iiTIHG l'TOT~.
CounciJ. ~ February/Jllai~ch
'rhe February Council meeting was held on Saturday the 15th, at the
QTH of Peter, VK7PF. Apologies were received from Messrs. Yeoman and
Rand. After the minutes of the previous meeting were read and
confirmed, the subject of Divisional equipment held by the Southern
Branch \!CB discussed. The Southern Branch will be approached with the
view of asking that Branch to do a stocktake on Divisional equipment,
at present residingin that Branch.
Included in the corresrondence Y,as a lfomination Form for Federal
Councillor from Peter V:K7PF. 11s this was the only nomina ti om rocei ved,
Peter was elected Federal Councillor for the ensuing year 1975. Also
tabled in correspondence vras the report on tho 17th J .O.J,..
The Council discussed the subject of the Merit L.ward and resolved
that it be included as a 11 otice of Motion for the 1975 :,.. G.M.
The March Council meeting was .held on Saturday the 15th at the new QTH
of Reg VK7KK.:. ·. Present were Messrs. Frith, van Stavoren, Fraser, Rand,
Carter, Yeoman, and Enmett. JSter the minutes of the previous meeting
were read and confirmed, Council nominations 1rore received from VK7's
JJ{, JV, FB, ZAQ, ~~BY, KK, PF, and ZGJ.
Six applications for nr.embership rroro recei vod from the following:
Stephen Russell, of Ulverstone, for studei1t membershi1 ·
Stanley Burtt, of Devonport, for associe,te nembership
1~1an Holmes, of Launceston, for associate membership
James Davis, of Latrobe, for associate membership
Bernard 'I'urner, of Burnie, for assoc:i.ate membership
John Wicks, of Ulverstone, for 1:tssociate me:nbership
Lfter due consideration, all of the above 1,-ere passed for
membership. The Council welcomGs you all to the VY:7 Division.
As this is the last Coun.cil meeting for the year, the Cormcil
would like to thank the Drenches for all thei:t co-operation during
the yeo:r and hopes that the i:1.coming Council will recei vo the srune
co-oper2,tion. ;Jee you all at the L.G.IL
73 • Brian i7.K7ZBY
The Febnrary meeting of the·northern Brw.1.ch was hold as per usual
in the 1~. E.B. Rooms, :i:Iigh Street; Launceston, ...-Tith thirty members
present 9 an inprovement on the January meeting.
The meeting vas informed by Ed~ VY7EE, thc1.t discussions with the
Launceston City Council on the subject of Clubrooms were still in
progress. Further details ·1rill be made knovm when available.
The meeting was then infori:1ed by Peter, VK7PF. that in line vvi th
the Department of Transport's 80 per cent cost-recovery programme,
prnver charges ,rill novv be made for the Mt. Barrm7 repeatW!'". VK?R1J1.
After discussion, the meeting agreed to pay the $32 per year for p0v1er,
and the ~);35 per year for the facility of having the repeater on standby
emergency l)ower.
6.
MEETHTG ITOTES (Contd.)
The Editor of the Northern Branch's Bulletin (Q,RM), John VK7JV,
indicated that hG would be resigning from this position and that a
net, Editor .i;,ould have to be found to· fill the position. I know I
speclk for all of the Northern Bfanch, John, when I say thank you for
a job well done •
.The meeting was then presented 'ivi th an excellent talk by Ed Bovis,
VK7ED, on JEarly Sea-faring Radio, in the days vhen spark transmi tt-ers
and sailing ships ,7ere all the rage. :Ed went into the·problems·that
an operator of a spark transmitter had to contend with, such as, after
every transmission a new spot had to be found on the Cr-Jstal Detector in
'b:l:ta Receiver, .oecause it had been burnt out by the transmitter. The
approximate pcw~r output from these transmitters ,ras 1.5 k:w·. As
technology improved, the range was increased, and with better receivers
and transmitters, break-in operation vas possible. After hearing your
tc.lk on early sea-faring radio, and the problems encountered, I think
•We can alJ. appreciate the advancements -made in the field of communications.
From aJ.l those present~ many thanks Ed, for a raost informative talk on
a most fascinating subject.
1'he meeting closed at approximately 2230 nrs. for the usual
1
~efreshments and eyeball QSOs.
73, Brian VK:/ZBY
March sav, the 1~.G.M. for the northern Branch once moro a:::id this
enticement produced a roll up of 36 members.
Prior to the election of Office Bearers, sev~ral items were
brouglit up. As John, VK7JV, was relinguishinc his post as Editor of
QRM, a ceneral vote of tho.nks WC>,S passed by the meetint; for his
tremendous effort in the past. We wish the new Editor, Graham,, VK7ZGG,
the best of luck i;;ri th bis nm; venture.
1~ point raised by Ed VK7ED, was 1ahether all technical articles.
published in QRM and Bulletin should be for,-;arded for publication in A.R.
Of several ideas put forrmrd, it seems that the greater percentage are
not of sufficient tech:r,J,cal standard and/or there is such a delay in the
articles being published in A.R. tho.t duplication 11ould not really
matter anyway,
The PrGsident Rog, VKTK!!.. 9 then tabled his li.nJmal Report, follovmd
by Kevin VICTZAJ:I, who presented his trading accou..vit for the equipment
store.
The election of office bearers for 1975 then folloued. These are:
President: :Brian VK1ZBY Lecture Officer: Wally VICTZWX
Vice-Pres. lg Lindsay VK7ZLD Q.,SL Officer: Col 1lICTLZ
Vice..;;pres. 2: Reg VICTKK Branch
Secretary: Ed Vl{7HE Correspondent: Bob VICTZHF
Treasurer/ nofreshment
Equip. Stor0: Ke,.rin 'TICTZli.H Officer: Reg- VlCTKY
QRM Editor: Grahara VK7ZGG Audi tor: Carl Walcto:rm
The Annual General i'feeting closed at 2015, to be reopened at 2025
for a Gene1·aJ. Eeeting by the ne,r Office Bearers.
7.
MEE'J:PTG I;OTES (Contd.)
Alan Holmes uas -r,olcm:-ied as a member to the Horthern Branch.'
Ed VK7HE, reported no ne,1 developments on tho Clubroom investigation.
He also requested. that peorlle intending to o.ttend the Divisional li.• G.H.
and Dinner 011 the 5th l1pril plG£tc:.1e let him or Kevin VJ.CTZAff., la.10-,7 before
the deadline, the 1st April.
Finally, Mr. John Hodson, an engineer ,Tith the P.H.G. gave the neeting
an inforrna tive and 2, t times cunusing lecture on the transi ti611 from black
and white to colour of the X.c:1tional J'elevision Tronsni tters, in particular
1
the Mount Wellington stahon.
It appears that rtmateurs nre not the only ones that eni t spurious
radiation fror;. their· transmitters, even if i t is 6Odb down - on 2Ok or
2OO1a, E.R.I'.
73, Bob 1/ICTZRF
S0l2ther::.1 Branch April
At the April meeting of the Southern Branch, held at the QTH of
Tor,1 Allen VJ{7}J.,, only nine members vore present, and alth0ueh this did
constitute a quorum, it was decided not to p ~oceed ·;Ji th the main
1
business, the election of office-bearers for the coming year. The
reasons behind this decision \7Gre several. Firstly, not enough
r~oBinations (or volunteers) 1.1ere received for tho·v::i.cant positions.
secondly, in vieu of the seemine lack of interest, it 90,s questioned
as to ·,,hethor the Branch should be continued, sc; it ,,-;as decided to
attempt to canvas the OI)inions of as nany nom'bers in tho South as
possible, before 2,:..'1Ythi11g further is done, Until then, ,re still have
last year's office-bearers.
In order to determine the feelinss of mer'.1bers, and o,,.v;iateur non.:..
mfnnbersj a specio.l Genorf,l I,1eeting is to be held at Tom AJ.len' s QTH,
22 Karoola Road, Lindisfa,rne, on Vvodnesd1:1y Hay 7th~ at, 8 p .n. As
stated, all members inter·osted are nskod to come along, a:,.1d as many
m::m,teurs who are not nemberfJ will be notified - the Branch has funds
and equipment, and only a snall fsTOU-J of those 11ho arc a,ware of it
see:C'l. interested in using the:ri. Perhc.J;.,s there are others who could use
them r:.lso, :possibly uuch uore effectively. J1s a background to the
s1;ecial General Meeting, the follm,inc is a brief sunmary of discussion
heard at the A1)I·il meeting, and of tlrn state of the Branch at present.
It i,7as generally acknoul0c.ged that interest in the W.I .A. in the
South has been declining, r:s heel the interest in radio generally; both
IIP. and VHF operntors seem to be less active (on the air, at least).
Many people e:iq:Jressed o:pinions as to the reasons for the decline; these
j_ncluded the fact that W.I .~i. meetings held 119 interest for members;
they had 110 intere3t in procedural natters and they found nothint;· else
at r,1eetings. Somo lectures. cmd social activi tie;:1 uere organised, but
the lack of sup1,ort 170.,3 disheartenine to the organisers, giving them
no incentive to e;o on. i1 lack of interer3t and support ·,ws also the
reason for the lagginr; activity in group 1,rojects, m2,L1ly the new
repeater.
A sug0 estion \7as nade that the Branch should hibernate for tHelve
months or so, but such a decision could not be made 1-Ji th so fevt members
present.
8.
MEETING. HOTES (Contd.)
.The state of the branch is probably reasonably well lmovm to most
members, and the following is just a brief summary. There are several
p:rrojects and activities which are beine carried on mainly by a fev:
interested P.1embers, on their mm, and with little interest, encouragement
or support. 'l'hese include the Saturday riorning Y .R. C.S. classes, which
are going extrenely vvell although the interest is about half a dozen
members and a couple of interested~- menbers, The Divisional
broadcasts once every three weeks, and the 1'e-broadcasts every v,eek -
again a few interested :::ieoplo keep it going, but their efforts are
hardly rewarded by foe numbers checking in on the callbacks, especially
on VHF. The last project is the coristruction of the repeater - to date
only about four people have shown much interest, and they have done all
the work so far, although several new faces have expressed a great deal
of interest lately. This group is Y,'orking under its mm ir:rpetus.
Finally, the state of the Branch finances: we are ru..."111une an
equipment store which has been very poorly supported in recent times,
even though prices on the raI1ge of items stocked have been very good.
Tho equipment store has been financing the repeater project to date,
although with miserable turnover, is making quite a hole in the funds.
The clubhouse funds stand at about $3700, mainly in fixed term deposits,
all of which will me. ture by AUe,"11Gt 1975. We have had soveral offors of
land on which to build a· clubhouse, one of which \rould be more than ,
suitable in all respects, if the offer is still open. li.ssuning then,
that we do not have to buy any land, the clubhouse funds at present
1lill go a long y;ay tmmrds providing material for a building.
These then, briefly, are so:ne of the i temz \7hich will be brought
foward: should be 1mintain the Southern Branch, and supy)ort the V,'.3,rious
groups a...YJ.d projects already struggling along? Should '.70 start on something
new, which vrill have the support of raore thru.1 just a few? Or should 110
let the Southern Branch dio a natural death, in the hope that perhaps,
at a more fertile period in the future, it nay rise again? Interest in
radio and electronics is still strong, on an individual basis - people
are still sitting for their .'i.oO.C.P., and the Y.R.C.S. has raany keen
young members; perhaps, if the W.I .ih i.n this area can re-:..<!11..::idm. itself
to proraote radio and electronics, for individuals and groups, then ve
may be able to do far 11ore good and interest more people, than we have
in the })ast. It is horJed that the meeting on Wednesday May 7th uill
discuss and hopefully resolve many of these points, and conclude vri tl1 a
concrete plan of action for the future.
If anyone is unable to attend this rreeting, for any reason, and
has some ideas, or opinions, these 1-:ill be well received by either Phil
Thompson VICT:S3, or A.'1.drew Boor VI(}i\.W, verbally or in writing, prior
to the meeting. But everyone 17110 hL-1.s any interest at all, no rratter
how slight, in the W.I.J1. and radio, is urc;ed to mnko an effort to
conre along to Ton' s place.
Sieyecl: Andrew I3oon VK7AW
Phil Tof:lpson VIr7SS
Fl'.'011 Hike Jenner VJCTFB cone13 a request for the dossier tlhai; was
compiled and Y,Ti tten by the late Lon Jenson VJ.CTLJ, on the VK.7 Division
since its inception. Anyone having this dossier, or krwwing of its
whereabouts, please contact Mike on one of the follo"1.1ing _phone numbers.
Work: 441611
Home: 478729
9.
C,\LCUL./,.'l1IOE,'3 OF WIND 10,.1DING ON TOJER AED J.NTENI-U. STRUCTURE Plill.T 2.
Roprintocl oxtracto fron Han Radio, Lu.gust, 1974
Jrlg. 3
Ur,_iform ·c1ind
force. 7.32 lbs ,"tQ FT.
per foot.
292.8 lb.
40 F'I.1.
20 PT.
10.
JTig. 511
477.6 lbs. 40 Pr.
20 Pr.
238.8 lbs.
Fig. 5B
40 FI'.
ll.
Guyed t0,mrs have the ac.l.vantc:.,geof regui·dng uuch le,Js structural
11s ar.~ e:x:l-t1JJJlG, a fJelf--su.pporti11g
n1t.1. to rial tI10.:n 2Glf-su.p11orting tc1.:.i-erso
700--foot ( 213. 4 neters) stoel tmrnr of conventional cleoign 9 uill veigh
about 460,000 lbs, (208,651 kg.)" :1. conp~,ra1J1e guy tower -;;ill ·c10igh
about 200,000 lbso(S0,718 kg.) i;_1.cluchng the \'.'eight of the guys. It
should be roL1enbered tlla t e. g~1.1yecl tm:or nust also be capable of
supporting; the guy-,:1irec-;. VT.hi le very fei;; auateurs are E.lo fortuno. te,
or u::.1fortun2.te, 0,3 to have a 700-foot to,:;"er, the m.,v:ings in material
of a guyed to-,rer is obvious.
Assune nm-r tho sane 40-foot tmwr nnd m1tenna array as previously
described haf::J a set of guy ;_,ires 30 foot ( 9 .1 netors) from the base of
the tover 1 a;J sho~;n in Pi.,£,°J 6 o _ ~roE the Pythagoro.::,,n theoren tho length
of the gu~r vire is ,i40"' + 30- = 50 feet ( 15. 2 rJeters) The
angle ·.:i th respect to ground is:
G == tan = 53.1 degreeo
For the sake of sim:pli.ci ty, wo Y.rill consider only one guy wire 0
This is 2.ctually the case vhon tho vinc1 is blo-vring touard the tm-.rer
fron the dii~ection in which the guy wire under consideration is
anchored.
It h; :;:wt generally appreciated, but a guy wire convorhi an over-
turning uoEont into incroa;JGd doYtm:arc.l streus cm the tm:0r 9 Ls previously
noted, the totGl horizontal force in this GXEJ),rplo is 293 lbs., (132.9
kg.) on the to11er plu,J 92 lbs. (42 kg.) on the antenna. ,Since the to:,o
of tlw touor is 110',T constrained by tho guy uires, tho overturning r:ioraont
is zo:ro. For this reason the structural .roquire:ments on the toner
tu1.d foundation are groetly reduced becau8e these i terns neod on support
the ·,.reight of tho D.f:lSGnbly arn1 t>e ad.di tioni'.,l load inposed by tension
in the guy y;ires.
Fig. 6 146.5 + 92 = 238.5 L B - - - -
m~rn FORCE.
/
I
40
F'r
LL:\.[)T
I
c~·uy
~~1ire
146.5 LB"
WIED FORCE
I
- 30 FI'.
12.
Because the horizontal force on tho tover - 293 lbs.(132.9 kg.,)
is uniformly distributed over the length of the touer, ,le -r:ill assume
that one-half the constraining force - 146.5 lbs. (66.5 kg.) - is
located at the top of the to\rer and one-half at the botton. The
horizontal force 011 the antenna - 92 lbs. ( 41. 7 kg,) M• w:illl be e.ssumed
to be located entirely at the top of the touer. This is ~hmm in Fig.
7•
. This allocation of reactiorw given mayseom arbitrary, but it is
difficult fo visualize a mechanisn by \,hich the 92 lb. (41.7kg.)
horizontal force of the antenna can be transnitted to the base of j;he
tower Y.ri thout generating a monent. .ilso, if there is any error, the
forces in the guy ;;r.ire will be overeDti,:iatod and not underostinated.
The tension in the guy ·,fire may be recolved into a horizontal and a
verticc1.l componcmt. 'I1he horizontal conponent nust be 238.5 lbs. ( 108.2
kg.) since it must exactly oqual the horizontnl windlo2.d (146.5 + 92
lbs. or 66.5 + 41.7 kg.). The tension in the guy \7ire itself nay be
calculated by setting up o. vector diagrOL1 as in fig. 8.
238.5
l!~,;-
b' = •;;:;~ 3G.•)0 -- 397 • 2 --1 b 0
Oo
IIor. i,J"incl force == 238.5 LB.
== 181 kg.
uhere F gw is the force on the guy Vertical Tension
uiro and the additional verticc.l conponent ill guy
conponent \:rhich nust be resiGted resisted i7ire
by the tover is: by tmwr 397.21B.
318 LB.
238.5
:!!' V == tan 36.9° :::: 318 lbr.~o
Fig. 8
108.2
F V = -tan
·---
36 .. 9 0 = 144.2 kg.
In other liC:rcls, an 86.6
mph (139.4 kph) vind vill
develop a tension of 397.2· lbs.
( 180. 2 kg. ) in the gu.y \7ire and
an additional vertical load of
318 lbs. (144.2 kg.) on the
tmiOr.
This vertical loo.cl is moro tl:L1::i.l1 the \!Oight of the :tntonnat It
should also be erJphasised that these loads are in addition to the vertical
loads caused by the initial tension in the guy uires.
So far Yo'e ho.VG considered thG in,z-olvo;nont of just one guy ,1ire. Slhen
considering- ti:ro gu;r ·.Jiros you nigl1t think that for the sar:o horizontal
vind load, the teiwion in. onch guy c;iro T,ould l:ie one-half the tension for
one \7ire. Unfortunately, it doos not 1,;ork out that easily. · Lo·!;' s
considered c, touer held by three g,J.y 1·Jires ilt 120° intervals, c,s shown in
Fig. 9. This is a typical arro..ngenent. If thG uind blm,s in the direction
of arrow "f,.", guy 11ire nunber 1 truces the \find load and the si tuo.tfon is
as explair.Led for one guy Hire~ If the Y,ind blG,:s s.s shmm by arrm, "B",
things are slightly different, as shmin by the vector diagran in Fig. 10.
Using the saine numbers as in the oxample above, the horizontc:.l l,ind load
of 238.5 lbs. (108.2 kg.) is shared equally by guy kires 1 and 2, so ue
o.11011 119.3 lbs. (54.1 kg.) on each. In this case the third guy wire
carried none of the load. The horizontal force in thG direction of each
guy ,JirG io thus ~ 119 3
Fh -· cos o
60 0 = 238.5 lbs.
54.1
---~ o = 108.2 kge
cos 60
Fig. 9
Guy \lire
,l
Wind
Vc:Ctor
:B.
Ls in the prececling oxm::1plo 1 the tension in each gu.y -i;riro is 397 .2
lbs. ( 180.2 kg.) and tho vertica1 cor1poncmt of each guy ·Lire is 318 lbs.
(144.2 kg.) - a tota1 of 715.2 lbs. (324.4 kg.)o The total is thus
nvice the vertical 1oad gcmoro,ted by a uind blOi:ring in the sane direction
as n11:y 011G lW-:l TTire It is eas:'l to se:e t110. t \)iri.dlouds car1 o.dcl up pretty
O
quicklyt 'l'he use of :;_,i;.y "s:ires inpoDO,s a }JOnal ty in thr1t the touer and
foundation nust be:; desig:iod for gre[rter vertical loads. Tho ,lclva.11.tage of
guy wires is that the to,:or and foundation need not be designed to resist
an overturning i:1ono:1t.
Ju1 inporta:1t factor to be considorecl in tho installation of a guyed
touer is thiJ initial tension in tho guy \1iTGS& If thG GUY ·. ires aro too
loose, the tm.-or uill S'T1.y excessively. If tho guys aro pulled too
tic;htly, an oxceDs:i.ve vertical load r:my be put on the to,.-roro In fo.ct, in
large i11stc,lla 1cio:,1s it :1.ay be possitle to buckle the tover \:itJ1 excessive
ini tiaJ. tension. It is therefoi·e 11ocossc,ry to co:11)ro:ii,JG botveen stiffness
nnd re2.0011ab1e sized structural no,:bors in tho toirer.
Boc1:iusc of the increasing interost in 1250 khz. and CLbove, rn1d the
easy avail2.bili ty of go.rabolic G.ntemi:1D T,i th solid refloctorn, it i8 both
intere,sting and instructive to a:rl)ly the above principles to G paro.bolic
dish gnd. con:pare thsse ui tl1 the to\wr. ";Je ·,rill rwsune a dish ,.1i th a 10 FT.
( 3 ff3ter) dioneter and n 100 ~.:ilo-per-hour ( 161 kph) -.✓-indo Frou equation
1, the vincl pressure cause➔ cl by 100 nihl=per~hour vincl is 40 lbs. per sq.
ft. The projected areG is~
= 78.5 sq. ft.
o.nd the total horizontal ,;rind pressure is~
2
( 78.5 ft O ) x (40 lb/ft 2 ) = 3140 lbs.
If a 10-foot ( 3 neter) antermn is to look at the ho:dzon to see a
rising satellite, as sho,:n in Fig, 11, the noun ting structure uust be
at least 6 foot tall to provide a ground clearance. Thus, the nininun
overturning nonent 1.'ill be :
(3140 lh.) x (6 feet) = 18,840 lb-ft.
Note thn,t a ten-foot parabolic dish nountecl on a 6-foot support has
approxiua tely h,'i ce the overturnin£,· r.10n0n t as a three-e1enen t 20 ueter
beaz:1, uoun ted on a 40-ft. to•,1er.
14. Fig. 10
Rer-ml ting guy viro
tennion 397 .2 lb.
One half of the
total horizontal
uind force.
23E3.5/2:::; 119.3 lb •
.,,/
./
~~------------------
sido force cancolled by
guy ·wire No. 2 (in this t:nmnple)
Unfortunately, this is not the vholo ,3tory. T'he .::tbovo cr,lculations
are for a hec,d=on .. ind. Bxperiuents have shoun that the greatest Hind force
on a parabolic antem1.a occurs not for a hea.cl-on condition, but '.,hon the
uind is blo\i-ing at an angle to the antenna. o.xis, as shm:n in Fig. 12.
Fig. 11
• 1 ang 1 e J.s
For r10st an t·01111(:tS t his 11ina • o.JlIJroxir:,n ,. rQ , an d t]-ie
• .l.1.,G 1y '.)t;
naxioun force is 10'/~ higher than for a o \cincl angle. 'l1he reason for
0
this is that o.:I:; sone ·.7ind angles the roar surface of tho dich acts o.s
an air foil, -v,:llich dovelo1,s LD!'-T in a sinilar w:m.ner to 011 aircraft
uing, thereby incroa,3ing the horizontal force on the antenna.
J}acau::;e this extra force depends on the shape of the antem1a, it
nay not l)e the sor.1e for all paro.boJ.ic antennns. The antenna pernneter
that has the greatest effect on this additions,l lifting force is probably
the focal leng·th of tho rmtenn2. 2.,s this deteminos hou deep the dish nust
be for a given dianeter, and hence \7ill affect the LIFT/DR.ti.G co-efficient
of the dish. It is not prcwtical to give lift co--cfficients or 2nglos
of uaxinur.1 wind lo:.::ding for all cases, but a 10:,\; increaso in ·uind loading
due to lift at an angle of approxiuately 56° is proaba-bly n good
appnxination for nost parabolic o..ntennaso
The relatively largo 1.:inzl loc,ding of a parabolic dish can be
considerably reduced by _perforating tho dish. If the holes are snall
conpnred to the ,IaVe length of operation, the effect on antenna perforaance
\;:'ill be negligible, bu·t the 1Tind loading -;;ill be decreased considerably.