QRM
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QRM
A
September
Newsletter of the Tasmanian Division
of the
Wireless Institute of Australia
(Insert in ‘A.R.")
R.
DIVISIONAL DIRECTORY.
Postal Addresses:
Tasmanian Division: P.0.Box 1010, Launceston, 7250.
Southern Branch: P.0.,Box 123, Sandy Bay, 7005.
Northern Branch: P.0.Box 275, Launceston, 7250.
Northwest Branch: P.0.Box 194, Penguin, 7316.
Divisional Officers 1986/7:
President: Peter Frith, VK7PF.
Secretary: Barry Riseley, VK7RS.
Treasurer: Frank Beech, VK/BC.
Asst. Sec.: Robin Harwood, VK7RH (Also Minuting Sec.).
Federal Council: Joe Gelston, VK7JG.
Council Member: Byron Dilworth, VK7BD.
Vice- Pres. Arthur Tregaskis, VK7SE.
Vice- Pres. Russ Pitman, VK/ZRP.
Branch Notices: , o _
NORTHERN BRANCH MEETS AT 8 P.M. ON THE SECOND FRIDAY of each
month (except January) in Room G25, Swanson
Building, Australian Maritime College, Newnham, Launceston,.
Next two meetings: 12th. September. 10th. October.
NORTHWEST BRANCH MEETS AT 730P .M. ON THE SECOND TUESDAY of each
month at the Penguin High School.
Next two Eeetings: 9th. September. 14th. October.
SOUTHERN BRANCH MEETS AT 8.15 P.M. ON THE FIRST WEDNESDAY of
the month, at The Activity Centre, 105, Newtown
Road, Hobart.
Next two meetings: 3rd. September. Ist. October.
Broadcast Officers:
Divisional Co-ordinator: Arthur, VK7/GH, 34, Ashbolt Crescent,
Lutana, 7009.
Tel: (H) 002.284963. (B) 002.305600.
Northern Branch Officer: VK7AV Bill.
Northwest Branch Officer: VK/ZFH Frank.
Southern Branch Officer: VK7GH Arthur.
Broadcasts commence 09.00 every Sunday, normally originated on
2m., with relays on 80m., 40m., 144.1 MHz (SSB) and ATV.
LETTERS 10 THE EDITOR.
Dear John,
I do not know what the oldies are going to think
if they see the letter from me in July "QRM" which finishes
up "73's from". That " 's " wasn't there when the letter
left me, so I can only think that the "QRM" gremlins slipped
it in knowing that it would annoy me greatly!
Strictly speaking, I was at fault in using "73"
in a written communication as it is a telegraphist's
abbreviation for "Best Regards" when using the key, but it
is widely used in this way and also on telephony these days.
“Very 73" is 0.K. if you must add something, but never add
an "s" or, as is frequently seen, "Best 73's", the meaning
of which is "Best best regards's".
73. Chas. VK7CH.
Editor's Note: Thanks, Chas, for your comment. Of course the
error was inserted after the letter left you. What these "QRM"
gremlins, plus the idiosyncrasies of an electric typewriter
with 7JK as a typist, will do next to create havoc, no-one
can possibly tell!
Dear John,
Our worthy President seems to have stirred up a
hornet's nest, considering he stated "for comment only".
He certainly got that! Anyone who is trying to do a job
that nobody wants can be sure of criticism. I jnow. May I
explain my position as a full pensioner? A few years ago,
I applied for and received the pensioner's rebate. Soon after,
I learned that my rebate was deducted from Division. So I
gave the local Branch a cheque for the difference. I soon
decided that this was a farce and arranged to pay full sub
thereafter.
So I suggest that:
If you can afford it, and approve, pay the full sub.
—
If your finances are such that the rebate is important,
N
apply for it.
3. If it is impossible to pay at all, we accept that and
thank you for past membership.
If you are one who accepts all the benefits of the
W.I.A. without membership at any time, the above will not
apply. In my opinion, the sub is too much, but we have a
democratic way of dealing with this if enough members think
likewise.
Meanwhile, I will pay my sub in full without grizzles,
and hope that there's enough left to feed me and Mum.
Warning - watch your blood-pressure, chaps!.
Max, VK7MX.
Dear John,
I am writing to let you know that my callsign is
now VK/ZFM and not VK7ZBX, the change being due to an error,
not of my making, but at the DoC. (A photostat of their
letter was enclosed - Ed.). Several weeks ago, I informed
the Divisional Office in Launceston and the N.W. Branch as
well. However, there has been no response from either, so
I thought I would ask you to insert a line or two in "QRM"
on my behalf to publicise the change. As I worked for
several months with the incorrect callsign and also had my
QSL cards printed in the meantime, the whole affair has
been rather frustrating to me. During this time I have
worked several stations on VHF and UHF and I think this is the
best way to let them know. Thank you for your assistance.
Cheers and 73, Frank, VK7ZFM.
Editor's Note: Sorry to hear your "QRM" hasn't arrived this
month, Frank. I hope the replacement one has come by post
by now. All the stick-on labels for "A.R." seem to have been
guillotined in the wrong place with the result that callsigns
are half on one label and half on the next. I have a feeling
that "QRM" is probably floating around VK3, VK4 etc., as well
this month, and goodness knows what they'll make of it!
HOW TO GET HOLD OF THE EDITOR.
His name is John Rogers. His callsign is VK7JK. His l
telephone number is 002.293402. His address is:
No 1, Darville Court,
|
|
Blackman's Bay,
Hobart, 7152,
|
And when you lose your copy of "QRM", remember he's QTHR. When l
he is at home, the 2m rig is normally running and listening
v
to Repeater 2.
FURTHER CHAPTERS ON SIMPLE VALVE VHF GEAR, by VK7BD.
The following circuits may be of interest to readers of i
"QRM" - they really constitute a conclusion to my series of
valved 2m. gear. The designs are basically from (1) the VK7
VHF Group's VHF Communicator for the regen receiver and
(2) the Minitran 2, by VK2's ZTM, ZCF, and ZCK for the trans-
mitter and modulator. I divided these into separate sections.
All these have been built by myself and modified to suit
parts that are still available. Due to inherent drift, however,
in both the receiver and transmitter (0.K. in the 1960's but
poor by today's standards), their practical use is somewhat
restricted. Notwithstanding these problems, they will all
go together to form a basic AM Tx/Rx on two metres, and are |
a cheap way to get some simple VHF gear which is ideal for
general demonstration purposes.
12AT7 12BY7
L1
47pf
— '
- : |
S ' QFC |
4%
KEY
1SON ReGULATOR tooopF
(oPrionar) B
(oon ‘
0k AM W |
MoOULATED
e s1 250v. A.M. only,
X1 - 8MHz range.
LT - Resonant at 24 MHz L2 - 4 turns, +" dia. (32 MHz)
L3 - 3 turns, 3" dia. 144 MHz.
L4 - 1 turn insulated loop coupled in L3.
Key Jack is closed type when key not plugged in.
S1 - Make switch or change-over type wired as shown.
Oscillator and P.A. Stage of "Minitran 2"
(Refer "A.R." March 1962 for full description)
Coil details differ from original description. The ones
shown are those which worked for me.
The regulator tube in the Oscillator supply made little
difference to stability - note the two separate supplies
used for A.M., so no oscillator pulling occurs on A.M.
However, some pulling will be evident on C.W. where a common
supply is used.
It should also be noted that drift (severe by modern standards)
will occur, so a broadband receiver is a must. The regen
types I have described earlier are ideal.
REGEN
, *ur
280v
SPEAKER
|
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!{
.
S 5623538252y
Li+L2 =/% Torns /6 eavce %5"'DiA.
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I "
=
AT/ . 6BmM8 ;
R.F.STAGE AUDIO STAGE.
10pF tuning capacitor is a modified "Eddystone" VHF type
with only one moving plate.
REGENERATIVE RECEIVER FOR 2 METRES.
(Based on VK7 VHF Group "Communicator", "A.R." Dec. 1962)
This design is for single band use (as compared with the
previous design in "QRM") and is modified from the original
"Communicator" design where the audio amp was also the
modulator for the A.M. transmitter.
VIA is a grounded grid "amplifier" with unity gain to
provide buffering between antenna and detector.
VIB is a regenerative (plate) detector.
V2A and B form a "normal" type audio amplifier.
Byron VK7BD.
Dear Sir,
NAVY CONCERNED AT
CANCER DEATHS naval personnel who have coantracted
CANBERRA — The Navy is con-
{
cerned at the number of deaths from cancer or cancer-related diseases. i
cancer and cancer-related diseases of He suggested there could be some link
former personnel who worked at shore with asbestos used in ships and asbestos-
stations with high-powered radios, the related diseases.
Senate heard yesterday. “I hope the number of cancer-related
During the adjournment debate, Sena- deaths are simply coincidental and that
tor Austin Lewis (Lib., Vic.) said: “The some investigation would indicate naval
Navy has been...concerned about the personnel are not exposed to any more
number of fellows (ex-Navy personnel) hazards than the population as a whole,”
who have died in the last 12.months or so of .Senator Lewis said. .
cancer. The Deputy Leader of the Government
“They have all worked at naval shore in the Senate (Senator Grimes) said the
radio stations which have high-powere .Government would investigate the matter.
radio transmitters.” : The possibility that high-frequency
He called on the Government to make a radio waves could cause cancer was
thorough investigation into naval and ex- already being invegigated, he said.
I found this item in our local paper up here on the
coast and thought it would be of interest to "QRM" readers.
Max VK7KY - Sulphur Creek.
SUNDAY BROADCAST ARRANGEMENTS.
31st. August: Originator VK7RH, Robin.
7th. September: B VK7AMC (Maritime College
Club Station).
14th. September: B VK7#MX, Max.
2 t.
Is
t Hb
September.) Originators N.W. Branch stations to be
. .
28th. September notified.
Our broadcast co-ordinator, Arthur, VK/GH reports that we
have had callbocks on 40m. from N.S.W. and Victoria and even
from a VK6 (mind you, he WAS on holiday on the north coast -
of Tassie!)
Edsel Murphy’s Laws
/\1‘12;.*[)/))/’3 General Law as Applied to Amateur Radio
There have been attempts recently in several publications to obtain a unified
theory of the behavior of inanimate objects. These articles represen_ted dissatisfac-
tion with the predictability of the perversity of matter. All treatments of this subject
included contributions from one Edsel Murphy, the infamous rapsca{lion, qnd scala-
wag, who related in his thesis the basic laws relating to the be_h_a.vzor of xnanima{e
objects. Our author, having had 44 years of experience in building amatf?ur 'radzo
equipment, has compiled in the accompanying article a sample of the application of
Murphy’s laws to amateur radio engineering. : .
B.— Assembly
1) If a project requires n components, there
will be n — 1 components avaulable.
2) Interchangeable parts won’t.
3) Components that must not and cannot be
assembled improperly will be. -
4) The most delicate component will be drop-
ped. ‘ ' :
5) The construction and operating manual will
be discarded with the packing material. The
garbage truck will have picked up five minutes
before the mad dash to the rubbish can.
6) The necessity of making a major design
change increases as assembly and wiring of the
unit approach completion.
7) A dropped tool will land where it can do the
most damage. (Also known as the law of selective
gravitation.) . )
A DROPPED TooL WiLL LAND WHERE |T S8) A component selected at random from a
CAN DOTHE NMOST DAMA%:E. gALsO group having 999, reliability will be a member
KNOWN ASTHE LAW OF SEL of the 19, group.
: GRAVITATION))
9) Tolerances will accumulate unidirection-
ally toward maximum difhculty of assembly.
BY MYRON E. LAWSON,* WSACL 10) The availability of a component is inverse-
ly proportional to the need for that component.
11) If a particular resistance is needed, that
PR.\CTICALLY the entire scope of our hobby is value will not be available. Further, it cannot be
under the influence of Edsel Murphy’s Laws. developed with any available series or parallel
Without a thorough understanding of his combination. :
principles one cannot derive maximum pleasure 12) After an instrument has been fully assem-
from his work. In fact, you can’t even get started. bled extra components will be found on the bench.
His basic law is: “If anything can go wrong, it
will.” Or to state it in more exact mathematical C.— Wiring
form: 1 4+ 1 = 2 where = is the mathematical 1) Any wire cut to length will be too short.
symbol for hardly ever. 2) Milliammeters will be connected across the
To show the all-pervasive nature of Murphy’s power source, voltmeters in series with it.
work, here are a few corollaries of his basic law 3) The probability of an error in the schematic
which are applicable to ham radio: isdirectly proportional to the trouble it can cause.
A.— Design D.— Test
1) In any given price estimate, cost of equip- 1) Identical units tested under identical condi-
ment will exceed estimated expenditure by a fac- tions will not be identical on final test after being
tor of 3. ) | buried under other components and wiring.
2) Dimensions will always be expressed in the 2) A self-starting oscillator won’t.
least usable term. Velocity, for example, will be 3) A crystal oscillator will oscillate at the
expressed in furlongs per fortnight. wrong frequency — if it oscillates.
3) If the breadboard trial model functions per- 4) A p-n-p transistor will be found to be an
fectly, the finished product will not percolate. n-p-n.
4) In a mathematical caleulation, any errvor 5) A fail-safe circuit will destroy others.
that can creep in, will. It will be in the direction
that will do the most damage to the calculation. E. — Operation
5) Inany given computation, the figure that is 1) If a circuit cannot fail, it will.
most obviously correct will be the source of error. 2) A transistor protected by a fast-acting fuse
6) The probability of a dimension or value be- will protect the fuse by blowing first.
ing omitted from a drawing is directly propor- 3) Probability of failure of a component is in-
tional to its importance. versely proportional to the ease of repair or re-
7) In specifications, Murphy's Law super- placement.
sedes Ohm's.
F.— Trouble Shooting G.— General
1) After the 24th cabinet-to-chassis screw has 1) Inaninstrument or device characterized by
been removed to replace the under-chassis fuse, a number of plus-or-minus errors, the total error
it will be observed that the line cord plug has be- . will be the sum of all errors adding in the same
come disengaged from the a.c. receptacle. direction.
2) After the last of 24 cabinet-to—chassis screws |, 2) In any given miscalculation, the fault will
has been assembled, the driver tube will be found never be placed if more than one person is in-
under the schematic on the bench. volved.
3) The bleeder resistor will quit discharging 1 3) All warranty and guarantee clauses become
the filter capacitors as the operator reaches into l void upon payment of final invoice.
the power supply enclosure. The man who developed one of the most pro-
found concepts of the twentieth century is prac-
tically unknown to most of us. He is the victim of
his own law. Destined for a secure place in the !
engineering hall of fame, something went wrong. |
(With acknowledgments and thanks to "QST" Magazine).
PSS
NEW W.I.A. MEMBERS.
The following new members have been notified to "QRM" by
Frank, VK/7BC:
From Bradey's Lake: J. HILEY, VK/7JH.
From Golden Valley: G. De GROOT, VK/GY.
From Launceston: J.D.SEAMAN VK7NJIN.
From Latrobe: An Associate Member, D.A.ODGERS.
e e e e ee eP et
RADIOTORIAL.
Conversations with colleagues and friends at W.I.A.
meetings and Activity Centre groups seem to support the
view that W.I.A. monthly meetings should be much more widely
based than they are at present. In previous issues we have
talked about the need to interest younger members and recent
letters and comment in "QRM" have indicate strong views
on problems of future membership. Perhaps W.I.A. groups
should organise regular lectures, teaching videotapes,
demonstrations and experiments to be used at the normal
meetings. Business and W.I.A. politics should be the work
of the executive committee at each branch, and such work
ought to be completed, with decisions taken without the
lengthy thrashing around which often takes place in the
general meetings. After all, what does "executive" mean?
It means "action" - and if the committee lives up to its
name, there should be a great deal more opportunity for
the sort of content we have listed above.
T,
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