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BRI
Bfiiietin issued by the Northern PO Box 1010
Branches of the Wireless Institute Launceston
of Australia, Tas. Division. Tas. 7250
February 1974
Vol. 3 No 10
Registered at GPO Hobart
for transmission by post .
as a periodical. Category B. Price 20c
It was mentioned the other day that there are several members
who have no intention of renewing their WIA subscription.
'The reason they say is that they are not getting anything out
of it. What a lot of ROT ! The very fact that they have a license
and frequencies galore to operate on shows that they are getting
something. You don't really think you would still have them
without the WIA do you ?
What about some of the more obvious, like repeaters, satellites,
Amateur Radio magazine, novice license, 10 words per minute Morse,
the Q8L bureau, equipment store, local branch activities( yes your
local branch is the WIA ) and last but by no means least, the
recent reduction of import duties on Amateur tranceivers, the
saving on this one could be up to $150.00, this alone would pay
your WIA subscri?tion for the next 10 years. ;
Ofcourse you don't have to be a member to benefit from about 90%
of the Institutes work.
You don't have to work for a living either, you could live
on the dole, but if we all look at it that way we will not have
a WIA or an Amateur license or the dole for that matter,
Think about it , and when you have post that cheque to
PO BOX 150 Toorak, VIC, 3142
73 John VK7JV
MEETINGS
Febe 5th North West Branch, Lakins Hall, Ulverstone.
Feb. 8th Northern Branch, AEB rooms, High st.
Auction of donated equipment, proceeds to clubrooms.
YRCS
N
Feb. 23rd room 38, Kings Meadows High Scool.
Contests
Feb. 9th + 10th John Moyle Memorial National Field Day.
ARRL international DX contest
Phone, 1st full weekend in February and March
CW, 3rd full weekend in February and March
QuR. M February '74
Page 2
Northern Branch Notes by VK7LK
The success of the current V.H.F. season is reported elsewhere and
no doubt Branch members had a ball on 6 and 2 metres. Kevin, VK7ZAH
efforts in frequently contacting VK 3AKC twice daily on 144, 432
and 1296 for the Ross Hull Contest would have amassed him a large
score,
Holidays have spread members overseas, interstate and around the
Island. They have also brought a number of interstate visitors onto
the Repeater channel., Those recalled are 2ZKG, 3EW, 3ZPX, 3CCX,
3ZGF, 5AS and 5UN .
Our December Branch meeting is now history and, despite adverse
weather conditions, the barbeque was voted a success by the 30
gdults attending. Thanks, Joe and Phill, for putting up with the
invasion.
A second barbeque held on January 19th was not so well attended.
Twenty adults and 8 children gathered at the same QTH. Publicity
for this event would not have been so effective but it appears,
perhaps, that such events aren't required. Or perhaps there aren't
enough of them to create the need, Your opinions please OM's and YL's.
January's meeting was low in attendance as expected- 24 attended
certainly enough to justify the meeting., Visitors Alan Holmes and
Martin Greer were welcomed. The only correspondence was from one
source (and I hate writing letters). A surprise was our low bank
balance, $170, No, it wasn't Kevin that treated himself to a New
Zealand holiday; it just represents the large amount of gear on
order for you either unsupplied or not paid for.
At least your money doesn't just sit in the bank. To yield more
money available to place orders, if you owe the store for goods
received PLEASE PAY UP before the fellows have to aske. If you've
ordered repeater crystals you will be requested to pay before they
are available., Remember VK7 RAA changes frequency on March 1.
A note to XYL's. Remind the OM to take that unecessary junk to our
-— Y
March meeting. It will be out of your way and will be sold to
benefit clubroom funds.
Psgst OM's . Don't worry too much, You can buy more, better gear. The
money still goes to the clubhouse funds- all you need to do is get
it past the XYL when you arrive home! .
Two losses to the south are David, VK7CY, and Steve, VK7Z8F, who are
continuing their engineering courses at the C.A.E.. Brian, VK7 ZBY,
offered to take over from Steve the task of keeping the Tas. Bulletin
in touch with Northern happenings. Associate Tony Polowy spent some
time in hospital during the month; trust your're now fit again.
Congratulations to Trevor, VK7 TB, on his marriage to Carolyn. Despite
it being their honeymoon he still managed to visit Robbie's disposal
store while in Adelaide to pick up some goodies.
Daniel VK7 ZDA and Vicki also are to be congratulated on the birth
of a daughter, Karen Louise. Surprised that the P.M.G. weren't
concerned about Daniel; with that lack of second harmonic suppression.
Associate Peter Guenther also figured in the news. He represented the
state at a Secondary Schools Mathematics Summer School in Sydney.
Seems we have a future computer expert in our midst,
Perhaps its not a first but Peter VK 7PD's recent operation from
Tasmania's highest point, Mt. Ossa, shouldn't go unrecorded. Peter
used his Ken transceiver to use the Repeater from a number of high
points during a recent walk through Cradle Mountain Reserve,
73 Reg VETKK
QeReM, February '74
North Westnotes by Max 7MX Page 3
I propose to continue with a talking point each month
until I run out of ideas or get clobbered. This month it's
Breaking In. Some operating on H.F. bands during the holidays
made me very aware of an increasing habit of busting in on a QSO.
This thing seems to have crept in until it now appears to be
accepted as normal.
It would appear that the day of the real amateur is fast going.
First he goes commercial and now one could assume that he is
getting to tired to call CQ.
As an alternative he listens around until he hears someone having
a pleasant contact and the next thing- break- break.
So the net grows, by the time it gets back one has forgotten
what it's about and excuses out thoroughly bored.
I have a feeling that part of the cause stems from all the awards
on offer., There are occasions when a break in is excusable such
as an urgent message or an old friend turns up, but even then I
often wait until the QSO is finished. Maybe I'm not with it.
Now the news, and there isn't much. Without a January meeting
and a gathering of the clan it is not easy to find out what
goes on ., However it seems that our members had a good Christmas
and entered the New Year full of Wireless hope.
The best news has been the repeated VHF openings for over a month.
Local operators on 2 and 6 have had a ball.
Allso there have been odd DX openings on HF. During the holiday
season several members have been on leave,
Graham 7ZAQ has been bushwalking in the hills, Ian 7ZIE has had
a shack and housework break, self 7MX did some trout fishing
and mountain travel, Harold 7MZ is at the time of writing
holidaying in VKi,2,% and 5. David 7MS has been awfully busy in
.
the tomato house, and rumour has it that Les 7LH has been carava:
some place. Tony 7AX is anxiously awaiting the arrival of a new
SSB rig for conventional, mobile and transverter use.
Maybe more news will be available after our next meeting on thi:
5th FEBRUARY 73 Max 7MX
) dishes 6ft diameter arrived in Launceston this week.
Phyll Mrs 7Z2GJ knew it was coming but didn't quite know what
to expect after all the kitchen is full of them. Joe had pointed
the dish in Juliana st out and told her that it was like the
smaller one but she thought he was kidding.
Well now she knows he wasn't and that a dish used by a Ham is
not quite the same as those in the kitchen.
Brian VK7RR is one of the few that never had the pleasure of
having had a Z call, untill he went to New Zealand for a holiday
and found that 10 wpm Morse just isn't good enough over there.
Brian was offered an on the spot examination at 12? wpm or a
T call, he settled for the latter and used the call ZL4TCX
during his stay .
Don't forget the Annual General Meeting and Dinner in Hobart
on the 23rd of March. The dinner will be held in the Prince
of Wales hotel in Hampden rd, Battery Point.
Book your accomodation now to avoid disappointment and lets
have a Gigantic turn up from the North and North Viestern Branches
Q.R.M. ~ February '74
Poem composed by M.Ives VK7MX. Page L
As recited by Max at the Tasmanian Jubilee Hamfest.
The Ham's a very busy bloke, he has no time to spare.
The shack is always pretty rough, with rubbish here and there.
This was the case around my joint, law and order was alack.
At least 1 found requirements, till the misses cleaned the shack.
I'11 never know what prompted her, she'd never tried before.
I really thought she didn't care, or knew the unwritten law.
But undeterred she sailed right in, the rubbish to attack.
She really did a dreadfull thing, when the misses cleaned the shack.
To gain access to most surfaces, she had to move most gear.
There was no harm in doing this, allthough results were gueer.
Most things she left just where they were, and didn't put them back.
So everything was back to front, when the misses cleaned the shack.
You know how things are left around, to hand when needed most.
Mine finished up in boxes, and virtually were lost,
I couldn't find a dad-durn thing, components now I lack.
I should have run the nuisance in, when the misses cleaned the shack.
Condensers were resistors, inductcrs packed with pots.
I could have sold some boxes, as mixed assorted lots.
There was no law and order, apart from a panel rack.
I bit my nails and tore my hair, when the misses cleaned the shack.
An RF choke was needed, by 7ZAQ.
I said I know I got one , and you're welcome to it too.
1 searched and looked and fumed and swore, my hair turned red to black.
It didn't help its missing still, since the misses cleaned the shack.
A mouse got in and made a nest, but I found the 1little pest.
It was very comfy in a box, but it went quickly west.
Now in that box was a piece of gear, 1'd lost from sometime back.
That incident shows what I mean, when the misses cleaned the shack,
This happened many years ago, it was never done again.
The lecture lasted several months, the message was quite plain.
She's quite a dear at normal times, but she sure got off the track.
The day she went and went beserk, and cleaned the flaming shack.
FOR SALE
1 - 4 El, 6 metre beam $10.00
1 = SSTV picture tube P29 phosphor $20.00
1 - 10 El. 2 metre beam $ 5.00
1 - 20 metre centre loaded whip. best offer
T, Briggs VK7TB, flat 2, 37 Woolven st. Launceston.
e esfe e s e ol e o
|
¢/
? Q.R. N, February '74
i Page 5
i
DX Notes by ben VK/DK il <
Well here it 1s February arready, and time has passed quickly.
1 would like to wish everjpone lots of rare DX this year.
Well quite a few things h%we happened in the last two months,-but
first I would like to deal! with some comments on the last notes.
I made mention of the pos&fibility of Clipperton Isl. becoming active.
Further to that, [ have hf{ard that a team of scientists are going to
Clipperton and that there lare 5 Hams amongst them, lets hope at least
one of them is granted a ljicense.
East Germany has been recofnised as a separate country by the A.R.R.L.
This will count as a separite country as from 17-9-'73 , but it
will be necessary to confifim West Germany after 17-9-'73 as well,
to get both countries on ypur credit. So get cards from these two
after the above date. i
The V59 mentioned last monih had the license revoked due to the
political situation. /
To the keen night owls, 20/metres has been open to Europe from
around midnight to 3am . On two occasions I stayed up to work them
and found myself in great demand, but I am sure it was only because
I was the only stupid idiot to be burning the late night oil.
In July 1972, VK3JW and some other Hams went on an expedition to
Mellish Reef, there has been some controversy since. but this has
now been resolved and it will be counted as a new country, bul only
on cards received after 1-4-'73 , by the A.R.R.L. The VK bureau
has been accepting.
Some rare DX stations active are as follows, XUTAA 1s sometimes on
S.E.A. net, 5B4LL has been heard, Vi3ALL/SU is said to be active
as is YK1AA . It looks as if CR9 may be active again soon.
VP8MF in S.Orkneys was worked by a ZL on 14205 at 0600 Z. but even
with my ears inside the speaker nothing was heard, well thats life.
What used to be the Territory of Papua, and the Territory of xew
Guinea are now both the same country of T.P.N.G. and it is
necesgsary to have a P29 Q5L for DiCC,
73 Den VK7DKX
VHF notes by Joe VL7ZGJ
The Ross Hull contest has now finished, we hope you have all
enjoyed yourself, if so please send your log to the contegt
manager. Lt appears,from listening around, that when the Ross
Hull finishes most VHF operators go QRT untill next year.
There are still many sporadic £ openings after the'conte§t closes,
During the contest all states were worked except VK9, ZL's wexre
very elusive in VK7 although ZL3AAN was worked by sgvera} Launceston
stations. Activity in the Launceston was very pleasing with
approximately 12 stations being active during the contest.
Temperature inversion across the Strait provided some very good
contacts with VK3's, all bands from 6 metres to 1296 Mhz being
usable. Kevin 7ZAH mgnaged to work Ro? 3AKC tw;ce a day on
2, 144, 432.and 1296 Mhz on quite a few occaslonsS.
gafiiel %ZDA is now operational on 14l, 432 and 1296lhz, varactor
triplers being used on the top two bands, his 6ft dlsh.w1ll be
mounted on the front of his house and should be operatlona}
shortly. Wally 7ZAZ worked ViL4FE on 14L.1 Mhz as far as I know
this was the only sporadic E contact in VK7 on this band, al@nough
there were many interstate contacts made on the malnlapd during
peak sporadic E openings, VK5 to Viae and Vi3 to VKu'belng the
most common, I wont go into details as no doubt you 11 read about
this in other publications.
P 73 Joe VK7ZGJ
QeRe M, February '74
6
Page
dB - dBm and all that jazz by Norm 7NR
What's a dB or dBm? That's a question often asked, we are not
referring here to the cost of something (sic), but to the arbitrarily
defined unit of gain or loss that came into general use about 1925,
Primarily developed for use in the telephone industry it was named
Bel. in honour of Graham Bell the 600 ohm expert.
The ear is more sensitive to changes of volume at low sound levels,
that is, it responds LOGARITHMICALLY to variations in sound
intensity. Therefore any unit to express power gain or losses must
also vary logarithmically in order to be practical.
The Bel is very convenient for comparing two power measurements on
a logarithmic rather than a linear scale because several gains
or losses can be merely added together to determine total gain or
loss. Other methods would be too complicated.
The Bél is too large a unit however, deviding by 10 gives us the
decibel or dB.
The number N of dB by which the power P.out exceeds the reference
P.ref is defined by,
Pout
N(in dB) = 10 log
Pref
N is negative when Pout is less than Pref
The non linearity of logs can be seen by plotting it on a linear
graph paper., see fig. L
Assume we are measuring the output power of a variable gain amplifier
The input power P.ref is held constant at 1 Watt, note that when
P.out equals P.ref the power difference is O dB,
FPowen
DIFFERGueE
+3
/! 23456 799 /O;// /2»-—-/,3 ‘4 /5)6
Powes Ovrrez (iWats)
) This non-linearity of logarithms canbe observed by noting:
tha. doubling the power corresponds to a 3 dB change.
Going from 1 watt to 2 watt is a 3 dB change so 1is
from L watt to 8 watt .
© dB change is a L times change,
Using the formula
Several useful conversions can be made;
1. _Power Ratio to dB
a) Assume an amplifier with an input of 1 watt and an output
of 2 watts, What is the gain in dB ¢
Gain in dB = 10 log Pout
Pin
= 10 log 2
1
= 10 log 2
from tables log 2 = 0.3 , s0 Gain = 3 dB
QeReM, February 1974
page
7
b) Assume now that the same amplifier gives an output
of 0.5 watt for the same input of 1 watte What is
the gain in dB ?
Gain (dB) 10 log %%%E
- 10 log %—5
= 10 log 0.5
= 10 (-0.3)
SN0 By
Note that a 2 to 1 power loss corresponds to
a 3 dB loss ( or a gain of =3 dB)
2, dBtoPowerRatio
The above procedure can be reversed by rearranging
the formula and using anti-logs (the reverse of logs).
since log £2%¢
in - Gain
70 (dB)
then Pout
Pin
== Antilog
: Gain
10
(dB)
a) Assume we have an amplifier with a 1 watt input and
13 dB gain, What is the ocutput power ?
Pout
. Pin =o .
Antilog 13
373 _dB
Pout = 1 « antilog 1,3
= 20 watt
An Easier Way
Now the above calculations assume that you have log taiL.cs
and that you are brighter than me and can use them,
There is an easier way and a great number of situations
can be handled withoub logs by using a simple technique
that requires you to remember 2 key numbers.
For 3 dB the key number is 2 o
For 10 dB the key number is 10
A 3dB change means a power change of 2 to 1.
A 3dB increase corresgonds to 2 times the power,
A 3dB decrease means 7 the original power,
A 10 4B change means a power change of 10 to 1.
A 10 dB increase means 10 times the original power,
A 10 4B decrease corresponds to 1/10 th original.
Remember also that adding logs is the equivalent of
s multiplying the powers of ratiose.
Q.R.M. February 'Th
Page 8
Examples 1) consider 6dB as 3dB + 3dB
since each 3dB is a power gain of 2
power gain of 6dB = 2 x 2 = 4 times °
2) Power loss of 20 dB = 104B + 104B =
1 1
0 <1
| 3) Power gain of 13dB = 3dB + 10dB = 2 x 10 = 20 times
L4) Power gain of 16dB = 3dB + 3dB + 10dB =
2 x 2 x10 = 40 times
Our notes so far have only covered measurements of power, our
concluding article will deal with voltage measurements.
33ksk o S s esfesfes skeosjesksk esk e skok eok K
eR gAR
ek
FOR SALE FOR SALE FOR SALE FOR SALE FOR SALE FOR SALE
1 only AR-7 receiver in original condition, complete with
power supply and all coil boxes (5)
Full coverage from 150 khz to 25 Mhz $75.00 apply to '
Mr. K. Berg , 79 Cherry rd , Launceston. Phone 25084
s e eo e i st el s sk s sk s e o
MR20B low band not converted, in very good condition $25.00
B.R.Waldron VK7CX , 62 Connaught cres. Launceston.
ssk ok ets esl ks sk ke
Copies of the constitution of the WIA Tas., div. are now
available . There are two ways of getting hold of a copy
1) attend the next meeting of your branch and ask the secretary
for one.
:
2) send a self addressed stamped envelope to the divisional
secretary at, PO BOX 1010, Launceston 7250 (15 ¢ stemp)
. es es 3% esie eskstslesfe sfesle sk Skok
New equipment around the place includes:
IGL tranceivers to , Graeme 72GG , Greg 7KJ , Dean 7ZAD ,
Phill 7ZAX and a receiver for Winston 7WH.
Joe 7ZGJ has sold his Galaxie and bought back his FL200.
Any day now there will be some smiling faces around Launceston
when the FT-620's arrive for Kevin 7ZAH and Daniel 7ZDA,
transverters for 144 Mhz are already in the making and no
doubt will be followed by 432 Mhz.
esiesl s stes slesk esl esl s e sk
MITS calculators are available trough the Northern branch.
One of the most popular ones has fixed and floating decimal,
leading and trailing zeroes are blanked, 8 digit LED readout
with error indication, L arithmatic functions plus square,
square root, reciprocal.and percentage in a single key stroke, s
Also includes a memory., This one is available to members only
for $82,50 if you are able to get a tax exemption. NON- members
price is $86.25 + tax unless tax exemption certificate is supplied,
0
QeRe Mo February 1974
" PAGE 9
1 MHz Stacked Arra D, St John, VK3AQR
(originally QST Oct 1966)
Advantages of this array are;
1. Easy to construct and match
2, Dimensions not critical
3. Ideal for DX scatter work L4, Gain about 14-15 dB
5, Wide bandwidth
— &2'?———1 14L=147 MHz
20
+
AD) SHoRTING
BAR
CoRAr
BOOM DIAMETER 3"
FRAME DIAMETER 1"
ELEMENT DIAMETER %"
SELF TRPPER
ELenenr Mouny gv
A few modifications were made to the original design to
improve performance on the section of the band used in VK., The
element lengths were altered slightly to improve the SWR over the
main part of the 144-145 MHz region. The horizontal section of the
H frame can be made of wood treated with Esterpol for water proofinge.
The wooden frame is believed to improve the pattern of 432 MHz beams
80 will have a similar effect on 144 MHz although aluminium tubing
can be used. The entire aerial used here was painted with Esterpol
and over the connections a silicon rubber compound of excellent
VHF properties was used. The matching stub used 300 ohm open line
and, as an example, the length from the shorting link to the point
A was approx. 39" and the balun was about 6" from point A.
Balun length was 26" and 72 ohm coax was useds
+ + A+ +
NOTE Fekruary is a short month, Contributions for liarch
L
'Q.R.M,' are required now,.
QeR.M. February '7.4
Distances from Launceston to Page 10
VK1 MILES VEL _MIIES
Canberra L37 Rockhampton 1264
Mt.Ginini u17 Toowoomba 995
Townsville 1536
VK2
Albury 369 VK5
Armidale 794 Adelaide oLl
Bathurst 567 Bordertown 490
Deniliquin 422 Ceduna 981
Lismore 939 Millecent LL6
Newcastle 641 Mt.Gambier 418
Orange 571 Murray Bridge 606
Pt.Macquarie 748 Port Pirie 757
Sydney 564 Renmark 610
Tamworth T4l Sterling 635
Wollongong 526
Vib
VK3 Albany 1642
Ballarat 318 Carnarvon 2226
Bendigo 356 Geraldton 2020
Frankston 251 Norseman 1532
Geelong 270 Perth 1843
Melbourne 274
Mildura 568 VK7
Mortlake 323 Burnie 67
Morwell 22 Devonport L8
Mt.Cowley 263 Hobart 103
Mt.Waverley 267
Tahara 38l VK8
Wangaratta 352 Alice Springs 1445
Traralgon 225 Darwin 2239
VR ZL
Biloela 1197 Auckland 1509
Brisbane 1032 Christchurch 1307
Bundaberg 1186 Dunedin 1205
Hughenden 1434 Wellington 1431
Ipswich 1004
Mackay 1406
Nambour 1075
QeReM, February '74
-
Distances from Devonport to Page 11
VK1 Miles VEL Miles
Canberra L3L Rockhampton 1255
Mt.Ginini 411 Toowoomba 991
Townsville 1518
VK2
Albury 352 VK5
Armidale 794 Adelaide 599
Bathurst 563 Bordertown LL6
Deniliquin 394 Ceduna 935
Lismore o Millecent ;00
Newcastle 6U5 Mt.Gambier 371
Orange 565 Murray Bridge 561
Pt. Macquarie 752 Port Pirie Yy
Sydney 568 Renmark 569
Tamworth Iy Sterling 590
Wollongong 529
VK6
VK3 Albany 1596
Ballarat 280 Carnarvon 2179
Bendigo 321 Geraldton 1972
Frankston 217 Norseman 1484
Geelong 231 Perth 1796
Melbourne 241
Mildura 531 VK7_
Mortlake 279 Burnie 20
Morwell 202 Hobart 132
Mt.Cowley 221 Launceston L8
Mt.Waverley 234
Tahara 339 VK8
Traralgon 205 Alice Springs 1404
Wangératta 331 Darwin 2201
VKL 2L
Biloela 1188 Auckland 1553
Brisbane 1032 Christchurch 1354
Bundaberg 1182 Dunedin 1253
Hughenden 1411 Wellington 1477
Ipswich 1003
Mackay 1393
-
Nambour 1074
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50 Brisbane Street,Launceston.
Telephone 2 2251
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