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BULLETIN ISSUED BY THE NCRTHER! Z(NES CF THE P,C.B°X 1010,
WIRELESS INSTITUTE CF AUSTRALTA TASMANTIAN DIVISICN LAUNCESTCI,
TAS. 7250,
DECEMBER
VL., 1, NC, 8
REGISTELED AT G,P.C, HOBART
for tronsnission by post as
o Pericdical, CATEGCRY B, PRICE 5¢,
PAGE 1,
M abuncdance of food, ¢rink an’ sunshine helped to meke the Hanfest at
Eveancdale a big success, Everything went in favour of the organisers with
approximately 90 people attending includin‘g interstatc and overscas visitors,
The 2 meter band was open all through the weekend and dozens of contacts
i\
with VK3s were made via the channcl 4 repecater,
The R.D, contest results arc out and we coengratulate the VK4 Divisicn on a
job well dene, I an surc that if we can talk 6 people into entering a log in
cxcess-of 1,000 points next ycar we can't help but win as we have the participation
p@rcontagc to deo so,
Duc to holidays therc will be no € R M of the printed variety in January,
Deacline for the February issuc is January 15th, If you have something that
may be of intercst ploase sond it to our P.(. Zox 1010 and help £ill and improve
your bullctin,
We wish you a Merry Christmas and a happy and nrosperous 1972,
JCHY VK7IV,
EDITCR,
' ) FII
36
DECEMBER MEETINGS
Tucstoy 7th YNorth West Mccting at Lakin's Ilall, Ulverstonc.
Fricay 10th Northern Zonc Meeting A,E,D, Rooms, 8 High Strecet, There
will be a lecturc on Aircraft Navigational Aids,
‘ JANUARY MEETINGS
Therc is no nmeeting in the North West in January,
VoL,1, NC, 8
oa1 o —————— ————
REGISTELED AT G,P.C, HCBART
for tronsnission by post as
o Periodical, CATEGCRY B, PRICE 5¢,
PAGE 1,
In abundance of food, drink md swnshine helped to meke the Hanfest at
Evencdale a big success, Everything went in favour of the organisers with
approximately 90 people attending includin.g'intcrstato and overscas visitors.,
The 2 meter band was open all through the weekend ancd dozens of contacts
with VK3s were made via the channcl 4 repcater,
The R.D, contest results arc out and we cengratulate the VK4 Division on a
job well cdone, I an surc that if we can talk 6 people into entering a log in
cxcess-of 1,000 points next yecar we can't help but win as we have the participation
p@rccntag‘o to de so,
Due to holidays therc will be no € R M of the printed varicty in January.
Deacline for the February issuc is January 15th, If you have somcthing that
moy be of intercst please send it to our P.C. vZ’ox 1010 and help £i1l and improve
your bullctin,
We wish you a Morry Christmas and a happy and prosperous 1972,
JCHY VK7JV,
EDITCR,
333303
. DECEMBER MEETINGS
Tuosc‘.ay 7th North West Meeting at Lakin's Ilall, Ulverstonc,
Fricay 10th Northern Zonc Meeting A,E,B, Rooms, 8 High Street, There
will be a lecturc on Alrcraft Navigational Aics,
JANUARY MEETINGS
Therc is no neeting in the North West in January,
Fricday 14th Northern Zonc Meeting A.E.D. Rcoms, 8 High Strect,
CCNTES
Dcecenber 11th -~ January 23rd Ross Hull lerorial VHF Contest, |
February 12th & 13th Jolm Moyle National Field Day,
The Nerthern Zone mecting held on 12th November was attended by 33 merbers
and visitor MAX TMZ,
Eevin 7ZAH reported that cguipment store sales for the month of Cctober
was a record $278, 0O,
John 7JV reported on the Council meeting and mentioned that the QSL Bureou
has hancdled 14,000 outgoing GSL cards so far this ycar, John suggested that
the load could be lightencd for the OSL nanaper if amateurs could scnd their
OSL cards dircet to the burcaus of sorc of the rorc comron countries .. like
Iwssian cards to Box 88 lloscow, If you scnd 7 cards in one cnvelopc direct
to an overscas bureau by surface mail 1t works out about the sare in cost,
Pcter 7PF rcportcd that the repcater was working fine and that recording
of stations using the repcater the previcus day had shown that 12 VK7s anc 8
VK3s hac used thc repeater,
Chris 7UX reported that thc opcration in the Scout Jamborec on the air
fron Paper Deach carm was very successful and that great interest was shown,
A lettor was rceccived frem the Girl Guides Association thanking us fer our
participation,
The mnceting was followed by the sale of sorc rorc cguinrent from the shack
of 7B0 end 3 Mullard films titled "Girdlc arcund the Earth", "Hand Solderced Joints®
and "icro Circuitst",
Supser was served at 11, 30pn.
e
o
s
sk
sk
W
=
S
s
%
e
%*
3
3
TH/NKS
As with any function the hard work of a few neonle makes ell the differcnce,
In the case of the Hanfest, thanks rust ge to the LADIES, withcut their hclp the
shew wouldn't have existocd, To thesc behind the scene in the kitchen organising
food and to all those who preparcd food dishes our sincere thanks for a job
well dene,
FeIHN -)(9( eIt
FILST on the list of volunteer operators in Jamboree on the Air at Paper Beach
next ycar is TREVCR 7TB, It a;pears the camm was manned by Girl Guides arcund
18 ycars of age!
0. R,
BULLETIY (F NCRTHER Z(NES, W.I.A. TAS........DECEMBER, 1971.
PAGE 3, '
VCRTH.WEST Z(NE NCTES
By the tinmc you read this, Koen 7KH will be back fron the land of
I"ip»-on, having no doubt tricd out his rccently acquircd knowledge of
Japancsc, ARIGATC GCZATITASHITA Ken,
After mony trials end tritulations Grahamn 7ZGS is now part of the
Channcl B nct, Nicc going Grahan,
Harold MZ is alsc back in thc nct, after an overhaul of his 2M gear,
Ve now rcgard llocl AR Mcbile Marinc on the "Australian Trader" as a
nerber of the local nct, We work Mocl cut at Devenport, Burnic and Dell
Bay on 24, Hc has channcl 4 crystals so look cut for him, His solid statc
ocutfit is rcally an eyeful,
Les 7LH was off thc air for a weck having locked the shack, Understand
a wedding in the family became very denanding, Cur best wishes Mnette,
Was very »Hlcased to hear frem Les 7Z2CF et Irishtown., We leoc
ferward te secing yeu a2t our meceting socn Les,
Tony 7AX is backt frem the land of Miss Australia 1972 lecoking very
brown, This timec a zenuine heliday with many cxperiences both Radic and
ctherwise, Hc assures me that working M and navigating city traffic is
not cermatible,
I again attended the Neorthern Zonc recting in Nevermber, Was
priviledged to try the new repeater, A renarkable effort chaps!
Wish the geod fairy would ¢ish cut scre channcl 4 xtals,
As T am cn holicday until 30th Decerber, have difficulty finding tirme
te premarc these notes!
CUL 73
X,
SRR KK
MURPHY''S LAW Presented by 7ZGLH
Prototyping & Procucticn,
1, Iny wirc cut tc length will be too shert,
2. Tolcranccs will accwmlate widircetly towards naxirun difficulty of asseml
.~ T e s . ee
Aftecr many trials and tribulations Graham 7ZGS is now part of the
Channcl B nct, Nicc going Grahan,
Harcld M™Z is alsc back in thc nct. after an overhaul of his 2M gear,
Wc now regerd locl 3R Mcbile Marinc on the "Australian Trader" as a
nerber of the local nct, We work Mocl cut at Devenport, Burnic and Bell
Bay on 2M, Hc has channcl 4 érystals so look ocut for him, His solic statc
ocutfit is rcally an eyeful,
Les 7LH was off thc air for a weck having locked the shack, Understand
a wedding in the family beecame very denanding, Cur best wishes Mnnette,
Was very pleased to hear frem Les 7ZCF =t Irishtown. We lcc'
ferward tc secing you 2t our meceting socn Les,
Tony 74X is bact from the land of Miss Australia 1972 lcoking very
brown, This timc a gzenuine heliday with many cxperiences beth Radic and
ctherwise, He assures me that working M and navigating city traffic is
not cormatible,
I again attended the Northern Zonc rmeeting in Nevermber, Was
priviledged te try the ncw repeater, A renarkable effort chaps!
Wish the geod fairy would c¢ish cut scre channcl 4 xtals,
As T am on holicday until 30th Decerber, have difficulty finding time
tc preparc these notes!
CUL 73
X,
FARHIAR
MURPHY'S
i
LAW Presented by 7Z2GR
Prototyping & Procuction,
1., Iy wirc cut tc length will be too shert,
2. Tolcrances will accuwrmlate wnidircetly towards naxirun difficulty of assembly
3, Identicel wnites tcsted under identical coenditions will not be identical
in the field,
Lo The evailability of a cormonent is inversly prepertional te the nced for
that comcnent,
Qo Ro Illl
BULLETT (F NCRTHERN Z(NES W.I.A., TAS.........DECR{BER, 1971.
PAGE 4,
RECEIVING A, T,V, (Assuming 625 line systen) STANDARD Aerin TRy
T - .
' 70 c.m. (STANDARB
L ONVERTER T V. Tures 7, CH g
Z/20"’ 450 MMz ReceWwER
Fron the abeve diagran it can be secen that very little cquinrent is required to
receive A,T, V,
AERIAL - This recuircs the use of a broadly tuncd (&1HZ) array cn the 70 Qf band
(420 ~ 450 MHZ), tlore about acrials in later articles,
70 Q7 CCMNVERTER,
Sclid statc technigques these days, allow for relatively easy construction
of 70 @ converter, The main aim in building an A, T.V. converter is that of cptirun
bandwicth (&IHZ), Because of the widebandwidth requirement, the converter usually
ecnsists of only onc stage of frequency ccnversicen, Two types of local oscillater
in the converter can be employed,
1o Crystal CSC., chain,
2. L, C(SC,
The crystel ose, is to be preferred because of the good frequency stability,
however this is not a majer factor, C(nc cdisacdvantage of using a crystal osc,
is the extra multiplying stages requircd for the osc, chain,
In L, Coscillator can work quite satisfactery as a fair amcunt of frequency
(rift can usually be telerated. c.g., 100XHZ drift is not cxcessive when the
bondwicdth of the T.V,chancl is in thc vieinity of 6 MHZ, At thc present tinc
I have two of these tywes of converters wmder constructien, If they comc
up to cxpeetations, I will cndeavour to procducc sare in a futurc issuc of C,ILLIM.
RECETVER,
ls mentioncd previcusly a stancdard T,V, rcceiver can be uscd (when
using 625 linc systen), The rceciver does not need modifying in any way.
The reeson for using channel 1 was nct just by acecident, When cdeciding what
channel to usc, many facters cnerge,
1. 18t and rost obvious, dec net usc a channcl which is in usc in
your viewing arca,
2, (nc must take inte account all the birdics and spuricuscs which
could occur, As fer as I know rost A, T.V. crs try tc usc
channel 1 if possible, as this appcars to be rclatively free
from birdies and spuricus signals fron oscillateors cte,
Next time a short article on transmitting A, T,V,
,
TNY (VK74X)
FHBRXK
WAN TED
A pocd quality all.wavc recciver having goed AGC action, scnsitivity
“GLO— 1’50 V)HZ I l I NeECLceEYWwWEIS I
Fron the above diagrenm it can be secen that very little cquirrent is required to
receive A, T,V,
AERIAL ~ This recuircs thc use of a broadly tuncd (&1HZ) arrey on the 70 @Qf band
(420 — 450 MHZ), tore about acrials in later articles,
70 G7 CCNVERTER,
Sclid statec tecchmiques these days, allow for relatively easy construction
of 70 Q1 converter, The main ain in building an A.T.V. converter is that of optirmun
bandwidth (&HZ), Beccause of the widebandwidth requirerent, the converter usually
ccnsists of only onc stage of frequency ccnversicn, Two types of local oscillater
in thc converter can be erployced,
1. Crystal CSC. chain,
2. L, C(sC,
The crystal osec, is to be preferred because of the good frequency stability,
however this is not a majer factor, C(nc disadvantage of using a crystal osc.
is the extra multiplying stages requircd for the osc, chain.
M L, Coscillator can work quite satisfactery as a fair arcunt of frequency
drift cen usuelly be telerated, e.g, 100KHZ drift is not excessive when the
bandwidth of the T.V,chancl is in thc vicinity of 6 MHZ, At thc present tine
I have two of these tyscs of converters under construction, If they comc
up to cxpeetations, I will cndcavour to procducc same in a futurc issuc of O,L,MM.
RECEIVER,
As rmentioncd previcusly a stancdard T,V. rcceiver can be uscd (when
using 625 linc system), The receiver does not need rodifying in eny way.
The reeson for using channcl 1 was not just by accident, When deeiding what
channcl to usc, many facters cnerge,
1. 18t and rost obvious, dc net usc a channcl which is in usc in
your vicwing arca,
2. (nc rust take into account all the birdics and spuricuscs which
could occur, As fer as I know rost A, T.V, crs try tc usc
channel 1 if possible, as this eppcars to be rclatively free
from birdics and spuricus signals fron oscillators cte,
Next time a short article on transmitting AT,V,
7
TNY (VK74X)
FHR ;N K
WAN TED
. A gocd cuality allw.wave recciver having good AGC action, scnsitivity
and sclcetivity,
The receiver need not have a product deteceter cte, as 1t will be uscd
prinarily for Cormicrcial DBroadecast DX,
R.L., GUNTHER, VI7LG,
32 WATERWCRKS RO AD,
DWYRNE, TAS, 7005,
Q.R.M,
BULLETIN CF NCRTHERY ZCNES W,I.A, TAS.........DECEMBER, 1971,
PAGE 35,
CPERATICN WITH THE DJ47C/DJ5KQ
(CCPY FRCM AMSAT
NEWSLETTER)
The DJAZC/DJ5KQ "H" repeater, described in the March 1971 issue of the
"Ansat" Newsletter, is a rmltiple-access, linear translator, receiving
uplink signals between 432.125 and 432,175 MHZ and re~cating them between
145,975 enc 145.925 MHZ cn the dewnlink, Sideband inversicn cccurs in the
translaticn process (i.e., upper sicdeband beecres lower siceband, and
vice versa),
To transrit signals threcugh this repeater, a 432 MHZ transmitter and
antenna delivering 200-300 watts of effcctive radiated nower (ERP) is
recormended, For best results SSB and CW should be used, [flthcugh A, B,
MCW anc AFSK will work with the repeater, these redes do nct make efficient
use of the limdted reeater pewer and should be aveided, We recorrend that a
Mrensverter" be used to frequency-translate from 28 cr 144 MHZ to 432 MHZ,
In this way, a ton cr two-ncter SSB or CW trensmitter can be converted fer
VFC~contrelled transnmission cn 432 MHZ, TFor CW operaticn, an armlifier/tripler
cen be used to frequency-rultiply the cutput cf a two-mcter transmitter
to 432 MHZ (see, for cxarple, Hem Radic, Feb, 1970),A varacter tripler con
alsc be used (sec the ARRL Hendbrck), Perhaps the lcast expensive methed
of generating CW power cn 432 MHZ is to cobtain a surplus 450 MHZ M
transritter strip and rodify it for CW cnoraticn on 432 MHZ, Mn article
cn this apprcach is planned by the ARRL Heacdquarters staff for a futurc issue
of QST, It is strongly recormended that scrne provisicn fer adjusting the
poewer ocutput of the transiditicr be included., This is cdesirable to be able
te adjust foer the rocper balance of satellitc repeater pewer arcng uscrs,
The antenna gain rccormenced fer transmissicn tc the satellite repeater
will cdepend upen the transritter cutput pewer, A 20 watt transmitter will
requirc a 10-12 D antenna gein tc cbtain the rceemmencded ERP of 200-300
watts, . better aphrcach weuld be te add a 200 watt power arplificr, in
which casec a dipole or ground planc shculd provide encugh uplink simal te
the satellite, and then there will be ne nced to kecp the antenna peinted
toward the satellite, The satellite antennas for this repeater will be
circularly polarized, so that lincer pclarization (either horizental or
vertical) can be erployed on the greund, Circular pelarization can be
expected tc provide as ruch as 3 dB cver lincar and is probably worth the
effert, DBecausc thc spacceraft will be magnetically steabilized, the
orientation of the satcllitc will be crnstantly changing and the scnse of
polarization will depend upon greund staticn location, Staticns in the
northern herisphcre shculd use right-hand circular pclarization, and those
in the scouthern hemisphere, left-hand circular,
For recciving, any gocc twe-neter converter shoulcd be suitable, and a
two=rcter rcceiving anterna having a gain cn the orcder of 10dB should rtrecvide
geed resvlts, Lincar polarization is satisfactory, tut again, circular
pclarization can be expeeted tc srovide as ruch as 3 ¢B irprovernent (usc
right-hand circular in thc nerthern henisphere, lcft-hand circular in the
scuthern herisphere ), If a 10-dB antenna is ncot abailable, a ground
nlane or cressed-dipole shoulcd nrovicde cdetectablc signals fren the rencater's
ten-watt PEP trensrittecr., The recciver should be capable of receiving SSB
and CW (i.c,, have a BFC, and a bandwidth less than 4 XHz), and’ rost HF
receivers should be sultablce frr the purpese, Transcelve cperaticn 1s not
recprmenced, becausc it is highly desirablc that all staticns be able te
ronitor their cwn downlink siegmals during the pericds in which they arc
transri tting,
CPERATICN WITH THE MMSAT TWC~TC.. TEN METER REPELTER ,
The /imsat twe-to~ten reter rcpeater, described in the March 1971 issuc
of the "Arsat" Newslctter, is a rmltipleseaccess linear -translator which
receives uplink signals between 145,900 and 146,000 MHZ, and retransnits
then between 29,550 and 20,450 MHz on thce downlink, Sideband inversicn ta-es
place in the translaticn prccess (i.¢e, upper-sideband beecres lower-sideband,
vice versaj). :
To trans—it sig:als fiucngh fllls repeater, 2 < :
antenna delivering 200-300 w=tis cf effcctive ruliaht‘.m(m S
recormendeC, For best results SSB and CW should be used, Lthough l!, K, e
MCW and AFSK will work with the repeater, these redes de net n=ke efficient
use of the limited reveater powsr and should be awided, Wc recorrend that 2
"trensverter! be used te frequency-translate from 28 cr 144 MHZ to 432 MEE,
In this way, a ten or two-meter SSB or CW trensmitter can be converted for
VFC~cntrelled transnission cn 432 MHZ, For CW operaticn, an amlifier/h'lplcr
can be used to frequency-rultiply the cutput of a two-mcter transmitter
to 432 MHZ (see, for exarple, Hem Radic, Feb, 1970),.A varactor tripler car
alsc be uscd (scc the ARRL Henc‘brck) Perhaps the least expensive methed
of generating CW power cn 432 MHZ is to obtain a surplus 450 MHZ M
transritter strip and rodify it for CW cncration on 432 MHZ, /Mn article
on this approach is planned by thc ARRL Headquarters staff for a futurc issue
of 05T, It is strengly recormended that scne provisicn for adjusting the
power cutput of the transrdtter be included., This is dcsirable to be able
te adjust for the roeper balance of satellitc repeater power arcng uscrs,
The antenna gain rccormencec fer transmissicn tc the satellite repeater
will cdepend upen the transmitter cutout ncwer, A 20 watt transmitter will
requirc a 10-124D antenna gain tc cbtain the rceermended ERP of 200-~300
watts, A better apnrecach weuld be te add a 200 watt power arplificr, in
which casc a dlnole cr ground plane shculd grov:t@o cnoux;h uplink signal te
the satellite, and then there will be nc nced tc kecp the antenna printed
toward thc satellite. The satellite antennas for this repeater will be
circularly polarized, so that lincar pclarization (either horizontal or
vertical) can be valoycr on the greund, Circular polarization can be
expected te provide as ruch as 3 dB cver lincar and is probably worth the
effert, DBecause the spacccraft will be magnetically stabilized, the
orientation of the satellitc will be crnstantly changing and the scnse of
polarization will depend upon greund staticn location, Stations in the
northern herisphcre shculd use right-hand circular pelarization, end those
in thc scuthern hemisphere, left-hand circular,
For recciving, any gocd two-meter converter sheuld be suitable, and a
two=ricter rcceiving entenna having a gain cn the order of 10dB should rrovide
geed resvlts, Lincar polarizeticn is satisfactory, ut again, circular
pclarization can be expected tc provide as ruch as 3 OB irprovement (usc
right-hand circular in thc nerthern henisphere, lcft-hand circular in the
scuthern herisphore ), If a 10-¢B antenna is not abailable, a ground
plane or cressed-dipole shoulcd provide cdetectable signals fren the repcater's
ten-~watt PEP trensrittcr., The receiver should be cg7ablc of rc,celv:Lng SSB
and CW (i.c,, have a BFC, and a bandwidth less than 4 XHz), anc rost HF
receivers should be suitablc frr the purpese, Transceivc operation is not
recprmenced, because it is highly desirablc that all staticns be able te
ronitor their cwn downlink signals during the pericds in which they are
transritting,
CPERATICN WITH THEAMSAT TWC-TC. TEN METER REPEATER ,
The /msat twc-to-~ten reter rcpeator, described in the March 1971 issuec
cf the M"irsat" Newsletter, is a rmltiple-access linear -translator which
receives uplink signals between 145,900 end 146,000 MHZ, and retransmits
then botween 29,550 and 29,450 MHz on the downlink, Sidcband inversicn ta-cs
place in the translaticn prccess (i.c., upper-sideband beecres lower-sideband,
end vicc versa),
Q. LM,
BULLETIN OF NCRTHEM' ZCNES, W.I.f. TAS..........DECEMBER, 1971,
PAGE 6.,
To transmit signals thrcugh the twowto~ten noter repeater, a twc-reter
transmitter and antenna ceapable of previding 80-100 watts ¢f ERP is recervendod, |
Fer best results SSBendCW shculd bc uscd, Flight tests with the ropeater
aboard aircraft cercnstrated that AL and IM signals arc nct very readablc when
rclayed by the repcatler, and they nake very inefficient usc c¢f the linited
repeater pewer (1.2 watts). CW eperaticn is ff(>rur'a.11y pessible with est two-
neter transmitters. The rest cipedient neans of achieving an 3SB canability
cn twe rneters is thrcugh the use of a transvertcer which can up-.ccnvert the
cutput of a ton, twenty cr siz-metcr SSB cr CW tramsmitter to two meters,
Transvertcrs of this type are available fren several anateur radic cquiprent
nanufacturers, and arc alsc described in the AIUL Hancbeck and the VHF Manuals
published by theRSGB andALRLRL, Transverters arc alsc usablc cn CW, and have
the added qr’vantage that thcy provide a VFC capability if the ba51c transmitter
elready has e VIC
The antcn-M gain reccrmened for trensmissicn to the two-te-ten reter
satcllite repeater will Cepenc upen the transritter cutput pewer, A 20 watt
tremsmitter will wire a 6.7 r’b antoenna gein to cbumn the recormencded ERP
ct 80-100 watts., Tt would be preforablc to use a ansuttcr in the 50-~100
watt power cutput class, se thet e nendirceticnaldipele cr ground planc antenna
2
can be erployed and pecinting of the antenna toward tho satellite will net be
nccessary, ihe Suel ito uc.-neter receiving entenna will be circularly polarizcd
so that linear polarizaticn {either horizental or vertical) can be crployed cn
the greound. e ClI’CU.lc..r" polarizatica is availeble at the greund staticn, as ruch
as 3 @B less transmitter power will be required for geod cormmmicaticns,
(Stations jn the northera herisphere sheuld use right-hand circular nolarizaticn
and these in the scuthern '10:.1@11@:0@ should usc left-hand pelarizaticn),
fny geod OF reccilver capable of receiving S8 anc CW on the ten-meter band
shculd be suitabie for rcceiving the ten.reter downlink signals if the recciver
sensitivity is one- volt/meter or better and the local noise level does not
excced thie level, &7"‘”'L'.‘tl"l" pelerized crossed-~dipele shoculd be adequate for
receiving in low-noei svirenrcats, but a higher gain entenna, such as a threc-
clenent bearn sheuld u‘,dc ke results, especially if it is circularly
‘*olarizry1 The s m"'-n’..tu ton-neor transittting antenna will be lincarly
clarized (a dipele), and Wurx.ag-‘ tading can he expceted e cceur just as was
the casc fer Aaubrel te-CSCAM5, 1uloss a circularly pclarized rceciving antenna
is uscd at tm, &j'l}at._a 'n, The uzc of Srenscelvers is nct recormended,
Swara tc tl ans nrent should be usced because it is
'm‘
Toto wendtor thelr owl dewnelink
5
\
si ’n(;LS whllu DT‘”II»JL"'tull'][’Z,
CPERATICNWITHTHLAUSTRALISj4d~%c../35 Mz FMREPEATER
The Australis 144 - 435 MHz rcpeater is now a cne channel cnly hard-limiting
*f-o'aoater of the derodulaticn..rercdulation type, and is designed to handlc M
mals only (CW, SSB and AM cannot be used w1tn this repeatcr) The repcater
rcccives A1 uplink signal cn 145.80 and retransrits on 435,10 on the downlink,
Telemotry 435,2 out,
Tremsminsion ol sigrzls threugh “he 144-435 MHz repeater will require a twe..
reter transmittcr anc antenna capable of providing a minirun ERP of 200-300 watts,
u;fl"‘”MM _ainuld be used, with a deviaticn of + 7.5 KHz, Available two-tcter FM
tpur“transccivers and converted taxicab radics sheuld opcrate satisfactorily,
but a power arplificr should be used to increase the cutput power, If the power
output is 50 watts, a 6.8 A3 antoina gain sheulcd be sufficient, It weuld be
advantagecus, however, Uo usc a power arplificr in the 100-200 watt pewer cutput
class so that a noen-directicnal dipcle, greund plenc or vertical antenna can be
oipleyed without requiring peinidng toward the satcllitc, The satellite two-meter
receiving antenna will be circularly polarized, so that lincar rolarization (cither
l’lOI'lZCntul or vortical) can bc uscd cn the greund, The usc of circular polarizaticn
cn the grewnd will reducc the transritter powcr rcquircrents by as ruch as 3 DB
(usc right-hand circular pelizzization in the ncrthern herdsphere, and left-hand :
circular in the scuthcrn hemisphere, R(-ccption can perhaps rost easily be achicved
threush the usc of a (:fod; 1cwqczse 435.-to-144 MHz receiving converter, which'
will ccnvert the sanc ; I tronsceiver Thflt is used for trensmssur
cn twe ETers 1S tharcuga TiC usSe ¢l a wransSverter wilch can up--ccnvert the
output of a ten, twenty cr six-metcr SSB cr CW transnitter to two neters,
Tremsverters of this type are available frenm several arateur radic cquiprent
nanufacturers, and arc alsc described in the ARIL Hendbock anc the VHE Menuals
published by ’bhu RSGB and ARRL, Transverters are alsc usable ¢n CW, and have
the added adven tage that they provide a VFC capability if the basic transmitter
already hes & VFC,
The antenna gain rcccrmened for transmissicn te the two-teo-ten ncter
satcllite repester will depenc upcen the transritter cutput pewer, A 20 watt
transmitter will reouire a2 6.7 dB antenna gain tc obtain the recormended ERP
ct 80-100 watts. Tt weuld be preferable to use a transritter in the 50~100
watt power cuiput class, sco that a nendirceticnal dipele cr ground planc antenna
can be erployed and pcinting of the antenna toward the satellite will net be
nceessary, 1nc satc ":i’so tuc..neter receiving antenna will be clrcularly polarizcd
so that linesr poliarization (either horizental or vertical) can be erpleyed cn
the ground. If circular pelerigzatica is available at +hu grcund staticn, as ruch
as 3 dB less trensmitter power will be required for geedcerzmmicatiens,
(Stations in the northera herdspherc should use l*ght..hanfl circular polarizaticn
those in the ecutherrn herisphere should usc lefit=hand pelarizaticn),
iy gccd IOF recciver capable of receiving SEB and CW cn the ten-meter band
sheuld be suitabie for roceiving the ten.meter downlink signals if the receiver
sensitivity is one-microvelt/meter or better and the local neise level dees not
excced thie level, A circularly pelerized crossede-dipelce should be adequate for
receiving in lewencisce eavirenreats, but a highor gain entenna, such as a threc-
clerent bear should provide botder resul ts, especially if it 1s circularly
aolarized, Thc szicliite ten—meicr tramsimitting antenna will be lincarly
selarized (a dipole fl v fading can bhe expected Te occur just as was
the case for fas uruJ8 rn‘lcss a circularly pclarized recciving antenna
is uscd at the gecund of Sranscelvers is nct recermended,
Scparate transn L'ttLrg ‘”“p]'.luflu sheuld be used beccause 1t is
! desirable hos 01 ge titnc be abie e wenitor thelr owa dewn-link
b“r1<,_'Ls whilec ©
CPE%TICI [ TRAVISi4dcr. /35 MzFM REPEATER
Thefustralis 144-435 MHz 1 neater is now a cnc “channcl. cnly hard-limiting
rcpeater of the derocdulaticn..reredulation type, and is designed to handle FM
signals only (CW, SSB anc AM cannot be uscd with this repcater), The repcater
I‘CC(,:LVGS BT uplink signel cn 145,80 and retransiits on 435.10 on the downlink,
Telemetry 435,2 out,
Treneminsicn o eizrzls thrcugh “he 144-435 MHz repeater will require a twe.
roter transritter and antenna capal16 of »roviding a minirun ERP of 200-300 watts,
Ouly M aiovld be used, with a deviation of + 7.5 KHz, Available two-reter FM
aratcur trensccivers and cenverted taxicab radics sheuld opcrate satisfactorily,
but a power arplificr should be used to increasc the cutput power, If the power
output is 50 watts, a 6.8 dB antoinagain should be sufficient, It weuld be
dvantagecus, however, o usc a powm:' arplificr in the 100-200 watt pewer cutput
class so that a nen-directionel dipcle, greund plane or vertical antenna can be
crpleyed without requiring neinwing toward the satellite, The satellite two-neter
rcceiving antenna will be eircularly polarized, so that linecar peolarization (cither
horizental or vertical) cen be uscd on the greund, The use of circular polarizaticn
cn the growmnd will reducc the transmititer powcr requircrents by as rmch as 3 DB
(usc right-hand circular polzzization in the ncrthern herdsphere, and left-hand
circular in the southern hemisphere. Rcception can perhaps rost easily be achieved
through the usc of a good, low-ncise 435.to-144 MHz receiving cenverter, which
will ccnvert the same two~meicr FM transceiver that is used for transnmission,
These ccnverters are cormercially aveilable, A highegain circularly pelarized
rceeiving antenna should be usced, with a gain of at least 12 dB, because this
satellite repcater is oxpectsd te provide an cut:ut nower of less than cne watt
ner channcl te indivicdual linearly pelari ed ronepele antennas,
Q. R M,
BULLETIN CF NCRTHERY ZCNES W,I.A., TAS........DECEMBER 1971.
PAGE 7,
PART 2 ; ELECTRICAL WAVELENGTH
e wavelength is the dinmensicn cccupied by the clectrecmagnetic field
for a single cycle of the apnlied R-F wvcltage,
. owme Cyels TRANS M5S0
P ONE V/AVELEMGTHN LIvE
oNenes
RF Gl
/\7.;?
DI Lomp
Y 'H”T“ul'
1 electrical wawlength is designated by the Greek symbel (lamba)., A
definition of 1 wavelength cculd be the lincal dirension cccupied by the
electric lines of fcrece created by all the arplitude variaticns of weltage
in 1 cycle,
wavelength in neters ()\)
A = Velccity cf the encrgy in meters per second
Frequency in cycles per seccnd
VELOCITY OF PROPAGATICN (V.P.) |
The velceity of prepagation clectrenmagnetic energy, (as it is advancing)
varies with physical nedia, Different kinds of transmissicn lines bear
different V,P, constants, : ‘
Some exarples s
300 % /07 é >
N METERS
€TE A = FHe ) FREE SPACE
( |
4 frequency of 30 MHZ has an electrical wavelength of 10 metcrs in free
space, thercfore a velocity factcr of 1 exists! But if the sane 30 MHZ
signal was connccted te a transmissicn line, the wavelength weuld be
scrie—what sherter then 10 meters, This length weuld cdenend cn the VP,
cf the trensmissicn line, * ’
Tyrical figures g
Cpen wire = V,P., o8&
- Twin lead = V,P, 82
Ccaxial cablc = ¥.P, 667
at 30 MHZ in free space = 10 meters -or 393,7 inches
at 30 MHZ in ccaxial cable having a V.P, cff 0.66 = 259,8 inches
PHASE RELATICNSHIP TN A TERMINATED LINE
0 = ZL
B
; .
i ~
W WS 4 / oM Cyels TRANSH o
‘e ; ONE V/AVELENGTN : L.m'r?‘ -
y
Az L/
I]
'
1
A =
p ,
!
CIRECTION
et
CF ADVANCE
Lons
1 electrical wawlength is designated by the Greek symbel (lamba), A
definition of 1 wavelength cculd be the lineal dirension cccupied by the
electric lines of fcrece created by all the arplitucde variations of woltage
in 1 cycle,
wavelength in neters ( A)
A\ = Velccity cf the encrgy in meters per second
Frequency in cycles per seccnd
VELCCITY OF PROPAGATICN (V,P,)
The velceity of prepagation clectremagnetic energy, (as it is advancing)
varies with physical nedia. Different kinds of transmissicn lines bear
different V,P, ccnstants, _ ' ‘
Scme exarples g e
IN METERS A =
300 % /O
: (7reE SPAC £)
FHz
4 frequency of 30 MHZ has an electrical wavelength of 10 meters in free
space, thercfore a velocity facter of 1 exists! But if the sane 30 MHZ
signal was conncected te a transmissicn line, the wavelength weuld be
scrcewhat shorter than 10 meters, This length weuld cdepend on the V,P,
cf the transmissicn line, , ’
Tyrical figures :
Cpen wire = V,P, o8&
Twin lead = V.P, 8%
Ccaxial cablc = ¥.P, 6&¢
at 30 MHZ in free space = 10 meters or 393,7 inches
at 30 MHZ in ccaxial ceble having a V.P, cff 0,66 = 259,8 inches
PHASE RELATICNSHIP IN A TERMINATED LINE
o0 = ZL
G.R.M,
BULLETIN CF NCRTHERN ZCNES W.I. A, TAS....o00e .DECEMBER, 1971,
PAGE &8,
" The phase of Veltage and Current changes every halfwavelength
therefcre in phase at 1 wavelensth,
TRANSMISSICN LINE NCT TERMINATED TC ITS CHARACTERISTIC IMPEDINCE ZG,
MISMATCH,
Energy sent down the linc tcwards the 1lcad finally reaches it, but is
cnly partially abscrbed, That nerticn nct absorbed is reflected frem the
load, and travcls back up the line tc the generater, The result is that
we have veltage and current waves travelling in two dircecticns sirwmltanecusly
in the line, The forward and reflected vcltage waves cembine and preduce
resultant sun v ltage waves kncwn as standing waves, The useful energy
abscrbed by the lcad is the differcnce between the ferward energy and the
reflected energy,
RESCNANT TRAMSMISSICYN LINES (CPEN CIRCUITED
sB ool
HI Z +H Z
A half wave cpen line bechaves as a 1 te 1 impedance transfecrrer,
et ég e
Low z Aow 5
Qe ee 0
A quarter wave cpen line behaves as a lew Z et its invut and a high Z
at 1ts cutput.
T—
RESCNANT TRANSMISSICN LINE SHCRT CIRCUITED
Lowd 2 im l ZOI;J Z our
A low impedance will appear at the input terrdinals cf a shert
circuited transmissicn line,
%—
A
‘HlfH z M l LO\u/ Z ouT
S,
Behaves as a very high irpedance at the in»ut,
TREVOR VK7TRB
£33 3%34363
VIIF GCNSTRUCTICN TIP
The gencrally accepted nethod of by-passing at VHF is to conncet the
capaclitors with the shortest ossiblc leads, but this may not be the real
answer., At 50me and akcve the lcad inductance and internal irductance
rust be considercd when selccting by-peass capacitors, In the VHF region
the loads car be used as the inductive elcenent of a serics resonent circuit.
Such a circuit is thce theorctical icdeal by-pass having close to zero
irpedance, The method is to twist the lcads together and grid dip for
frequency of operation, As an cxarple, at 144me a ceramic disc of 1000 pf
with 3/8 leads has an impedance of 12-16 chms, on the other hand a 25 pf
with 1 inch lcads is clese to zero impedance, In this cday and age of
transister circuitry where low impedances erc corren place, a by-pass
whose irpedance is eround, say 25 ohmns, would be cuite cut of place if
soint where the clircult immedance 1is of the sare order, AA
Lacrgy =i QoW ulCc LUIC Wwartes e 10at lilllall)y reaClles 1L, UUL Lo
cnly partially abserbed, That porticn nct absorbed is rceflected frem the
load, end travcls back up the line tc the generater, The result is that
we have voltage and current waves travelling in two dircecticns sirmltanecusly
in the line¢, The feorward and reflected vcltage waves cembine and preoduce
resultant sun veltage waves kncwn as standing waves, The useful energy
abscrbed by the lcad is the differcnce between the ferward energy and the
reflected conergy.,
RESCNANT TRANSMISSICI LINES (CPIN CIRCUITED),
I — —
HI Z Il Z
B ee e
A helf wave cpen line bchaves as a 1 te 1 impedance transfcrrer,
——— 3 —
—0
Low z Low 2
e e ee — .O
A quarter wave cpen line behaves as a lew Z et its inbut and a high 2
at its cutput,
RESCN/ANT TRANSMISSICN LINE SICLRT CIRCUITED
e
LO\V\/ 2 I~ [ ZC"I\/ Z ouTt
A low impedance will appear at the input terminals of a short
circuited transmissicn line,
X
.
Hign 2 l Low z ouT
P
Behaves as a very high irpedance at the in»ut,
TREVOR VK7 TB
2
3
e
S
VHF CCNSTRUCTICN TIP
The gencrally accepted nethod of by-passing at VHF is to conncet the
capacitors with the shortest cossible leads, but this may not be the real
answer, At 50mc and abcve the lcad inductance end internal inductance
st be considercd when sclecting by-pass capacitors, In the VAF region
the loads carn be used as the inductive elerent of a serics resonent circuit,
Such a circuit is the theeretical ideal bywpass having close to zero
irmpecance, The methed is to twist the lcads together and grid Jdip for
frequency of operation, As an cxaiple, at 144nc a ceramic disc of 1000 pf
with 3/8 lcads has an impedance of 12-16 ohms, on the other hand a 25 pf
with 1 inch lcads is clese to zero impedance, In this day and age of
transister circuitry wherc low irmedances arc corron place, a by-pass
whose impecdance is cround, say 25 ohis, would be cuite cut of place if
used at o point where the circuit impedance is of the sarc order, A
little attention to this immortant fecaturc, will ray dividen's espccially
in that high gain low ncise converter you are building for 432,
7AK,
0. Ho M,
\
BULLETIV (F NCRTHERN Z(VES W,I,A, TAS...es...DECEMDER, 1971,
PAGE ¢,
A METLE LIGHT WEIGHT BE/M,
SolDER To ELErmenT
\l CAMMA CAVPACITo,
Boom
7
GArM
A
Row
3lug
THG STRIP
REFlecToR 40"
SPACED 50 . COHX
E/Eflf/yrs
AT 187 CemrRES
1
This 4 clement bean was whinsped up in half a rorning end is currently
scrving duty for leocal centacts, If you noed a sceend bean or a cheap lightweigh
collapsable bean, then this should be of intercst te yeu, The beon is 3/4M
plastic conduit and the clerents arc fitted by drilling a helc two sizes too
small for the cleuents and then forcing them threuch, With carc it is pessible
te pull then out again anc. again without looscning ther, The clerents arc slight
offsct to allow the germe rmatch to be fitted to the centre of the driven clerent,
They need not be offsct if the bean is not required to collarsc, Elements in
the original werc madc from stiff Mo, 10 conper wirc althcugh 2" eluninirum
tubing will alse worz, The prototypc was not wcather proofced end a permoncnt
instcllation weuld require rore attention in this respect,
VK7 ZzM s
M. Mom\Le WHIT
-
78 X Long o’
?
AMMA
q Ron
3Lug |
THG STRIP
ReEFlecToR 40"
X
f/EME/yrs SPAcCeED S0 5. CoAX
AT 187 CemrrRes
This 4 clement bean was whinsped up in half a rorning end is currently
scrving duty for lecal centacts, If ycu need a sceend bhean or a cheapy lightweisht
collapsable bean, then this should be of intercst te yocu, The beon is 3/4M
plastic conduit and the clerments arc fitted by drilling a helc two sizes too
smell for the clerents and then forcing then threuch, With carc it is pessiblc
to pull then out again and apain without looscning then, The clements arc slightly
offsct to allow the garma rmatch to be fitted to the eentre of the driven clerent,
They nced not be offsct if the beant is not required to colla;sc, Elcments in
the original werc madc from stiff Ne, 10 conper wirc althcugh " aluninirum
tubing will alse wors, The prototypc was not wecathcr proofed and o permancnt
instellation would require more attention in this respect,
VK7 ZzM s
ZM. MoriLE WHIT
7 X Long
L= 11 TuRNS 14 Gauge
Tarms oPenes OR Closes For g
Turin
WHEN Timed CoveR VTR FRRALMPITE
500 Conx