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BULIETIN 1SuUED BY THE NORTHHERN PO BOX 1010
BRANCHES OF THE WIRELESS INSTITUTE LAUNCESTOL
OF ATISTRATIA TAS. DIVISION. TAS. 725G
AUGUST
VOL. 3 NC. 5
REGISTRED AT GPO HOBART
for transmission by post
as a neriodical. CATEGORY B PRICE 10c
Last year it was said that allowing the use of repeatzrs inthe
R.D. contest was a real hrainwave,
It resulted in an increase in points for most Z calls but more
important it gave them an increase in stations to work and
that coupled with being able to rework a station after 2 hours
gave bLhem their first taste of competition in an R.D. contest
This yoar repeaters are NOT allowed, however this division
) upon a little prompting by members has initiated a move to
T allow the use of repeaters again in this contest by writing
i tothe Federal Contest manager and all Divisional Councillors.
& What ever the outcome of this, it should certainly be an
agenda item for the next Federal Convention.
See ¥n the contest. JOHN VK7JV
_MEETINGS
AUC. 7th NORTH WESTERN BRANCH, LAKIN'S HALL, ULVERSTONE
BHANCH ANNUAL GENERAL MEETING.
AUG. 10th NORTHERN BRANCH, AEB ROOMS, HIGH ST
EQUIFMENT DISPLAY RVENING.
CONTESTS
AUC. 1€8219th R.D. DETAILS JULY AMATEUR RADIO.
i » AUG. 25&26th ALL ASIAN DX CONTEST
BULLETIN OF TH: WOR HF: ERANCHES W.I.A. TAS. August '73%
page 2 ;
Our last meeting drew an attendance of 31 members, 1visitor Basil
VK7BL (VE6BB) and that man from the coast, Ian VK7ZIE.
Many subjeéts were discussed resulting in three pages of minutes
being written upe.
Possibly the most important item was preliminary plans for the 1973
' Hamfest to be held on the last weekend in November at the Evandale
Memorial Hall.
Volunteers and press gang to look after the organisation are VK7's
'ZLD, ZAH, GW, RH, ZSF,ZBY allthough Brian doesn't know it yét. ‘
I have an idea I left somebody out but can't think who. i
I don't think these gentleman will have any trouble getting more 1
help if they need it. 4
If you have any ideas on improving on the last Evandale Hamfest
then contact any of the above, '
Kevin reported that we have {663,00 in the kitty and John reported
that we now have $880.00 in the clubroom account.
The @olden Jubilee came in for comment, 69 having attended and
. a good time heing had by all. ; }
Peter 7PD took the floor and spoke on a couple of subjects, one of
interest being a change of Club call sign to 7NB (Naughty Boys)
same wit sugested 7NW (Naughty Women) for the coast, Peter pointed
out that this would be more in keeping with the new set up.
R.D. contest came up for discussion and 7JV and 7RH stated that
they would go for the full 24 hours, more spartans are required
s0 how about it fellows? Even 12 hours per operator would help.
The use of repeaters for R.D. contacts are yet to be confirmed your
scribe awaits clarification on this from the Federal Contest Manager.
Fargot to mention that Peter 7PD has a source of cheap QSL cards
contact him for details.
Australis news from Peter 7PF promises exitement for the future with
OA7 scheduled for launch during the second quarter of 1974.
With an orbhit (planned) of 2000 miles and carrying a variety of
translators it should further enhance the interest started by
OA6 which is ten months old and still going strong.
No doubt Peter will suply us with full details of what the package ¢
will contain as soon as details are finalised.
7% NORM VK7NR
BULLETIN OF THE NORTHZRK BRANCHES W.l.A. TAS. August '73
page 3
In future, each month I propose to head the notes with a thought
provibking cohservation, a talking point, last month at least one
bloke got the message.
This month- ARE AWARDS A GOOD THING? In working 80 and 4O metres
nowadays one must exhibit a lot of patience, with current awards
running, no more can one have aquiet rag chew with old friends.
At allmost every over there are breakers in hordes and in trying
to do the right thing one often loses the original caller.
My record is theee hours non stop and then the BIG switch was
pulled with callers still there. '
It certainly is different.
OQur last meeting was certainly lively, the chairman had a bad
cold and I think the boys worked on this as during periods
of nose attention mueh square wave noise was generated by them,
very exasperating, my OSCAR went to 7ZJS with 7MS and 7ZlE
close behind.
I'11 bet that they quieten down at the next meeting, the ANNUAL,
when a call is made for office bearers, HI,
After the meeting and supper Tony 7AX conducted us around the
new telephone exchange and ably explained many of the complicated
bits and pieces, ably interupted by Bob 74J5.
It was pleasing to see two Kens 7£H and 7AL back again,
keep it up chaps.
ON A PERSONAL NOTE.
Les 7LH and David 7MS have both aqu#red TWOHUNDREDS so Devonport
should hold its own in the R.D. contest.
Bob 7ZJS was heard mobile on 6 metres, we now have several
operative on that band, wehave had some openings lately too.
Graham 7Z2AQ has come up with an ingenious whip lifter upper
on top of the car.
This became a necessity after little sister had wiped a couple
of whips off under the carport.
lan 7241E with some help has upended a steel mast on which a-
beacon aerial may sit some day.
And I 7MX have a steel tower stretched across the path waiting for
time and week end weather to add extensions.
IT'S A CRUEL WORLD . CUL 7MX
A note received from Chris VK7Ux said
Hi John and fellas
Had an enjoyable 11 days on the PATRIS from Melbourne to Singapowe,
2 hectic days in Singapore, I didn't buy anything but had fun
looking around, fantastic, most of the passengers bought,hifi gear
transistor radio's , cassette players, clothes, cameras etc.
Had a long flight by 707 from Singapore via Bahrain to London
and arrived at Victoria station after 2.00 AM being up for 26
hours. Been over London and am writing this from Hern Bay.
Radio and HiF1i gear here is half the price of that in VK cheaper
than Singapore.
All mail to C/o CBA bank, 34 Picadilly, London England.
73 CHRIS VKX7UX
Thanks Chris for the note and keep sending them, keep us informed,
how about a few lines about our hobby, how they go about it in
G land. Did you hear about the drop in tarifs in VK? prices should
come down quite a bit. CUL John
QeR.M.
BULLETIN OF THE NORTHERN BRANCHES OF W.I.A. TAS August '73
page L
The Northern eguipment store can now obtain all devices manufactured
by National Semiconductors at prices only slightly more than those
in the U.S.A.
A1l IGL equipment is still available on order allthough we will
stock a couple of 2 and 6 metre converters.
We have the following in stock
DALO etch resist pens $2.00 NEOSID
Ferric Chloride per 1b .60 SINGIE BASES 7c
TRANSISTORS DOUBLE BASES 8c
ON3563, 2N356l, 2N3565 .10 FORMERS 5¢c
SE1001 .30 SINGLE CANS 7e =
2N3055 $1.60 DOUBLE CANS 8¢ -
2N3866 ) §1.00 F16 SLUGS 2 - 12 Mhz 5¢ -
FET's F29 8LUGS 12 = 200 Mhz 5¢ i
oON52L5(TIS88) .95 XTAL SOCKETS o . ,29--55
2N3819 .70 MINIATURE 12 VOLT RELAYS $3.00
RIS :?g RELAY SOCKETS 45
ot VALVE KIT CONSISTING OF
-DIODES 1-6AK5, 2-6AU6, 2-6BA6 $1.00
EM4Y10 1000 VOLT PIV 1 AMP .45 :
EM4OL L4OO VOLT PIV 1 AMP .30 BELLANG. &, 1EE gégiETs 'gg
EM408 800 VOLT PIV 1 AMP .45 " " SOCKETS PCB .30
HP2800 HOT CARRIER $1.00 .
ZENERS 9.1 VOLT LOO MW 45 COAX CONNECTORS
RESISTORS PL259 PLUG .75
% and 7 WATT MOST VALUES Le 80233 ROCKET « 10
1 WATT BAGS CONTAINING . INTEGRATED CIRCUITS
APPR. 35 VARIOUS VALUES #1.00 MC1 550G RE/IF AMP 42,00
CAPACITORS 7,00 series 1IC's are available
CERAMIC 2,2Pf-820Pf LIMITED ex stock at various prices. _
OCK . B
EENIKTURE DISC 001, .01, °® L inch 8 Ohm speakers $2000
+047, 50 VW 5c CALLBOOKS 1973=75 %120
TANTALUM 4.7 Mfd 25 ¥ .25 . :
22 Mfd
10 16 VV, 1 Nfd 35 V
Nfd 16 .25 %2%883K§Ufi§g
3 2§PgRDER $5?oo
.
ELECTRO 32+32 Mfd 300 VW .30 FIBRE GLASS BLANKS FOR
fRé¥T§§§ «7-6Pf 1.5-9Pf o I.F. & 2 METRE 2 WHIPS
BOOKS ON ORDER ONLY ARE ON ORDER AND SHOULD BE
;EQL fiANfiBoox £5.95 HERE WHEN YOU READ THIS
ANTENNA BOOK $3.00 RADIO COMM. HANDBOOK $9.80
ARRL VHF MANUAL $3e30 AMATEUR RADIO TECHNIQUES ?
MOBILE MANUAL ARRL $3.30 VHF/UHF MANUAL RSGB $Le35
e e
BULLETIN OF THE NORTHERN BRANCHES OF W.I.A. TAS. August '73
Page 5
_A4th ALL ASIAN DX CONTEST
1. At 1000 GMT August 25 to 1600 GMT August 26
2. Entry classification, (A) single band, single operator.
(Bg multi band, single operator.
(C) multi band, multi operator, single transmitter
36 All H.F. bands, CW only :
L. Call : CQ AA
5. Serial numbers, OM stations, five figures, RST + 2 figures
derioting your age. YL stations, five figures, RST + 2 figures.
6. Scoring. .
(A) non Asian stations, a contact with an Asian station will
count one point and a multiplier of one point for each prefix
of Asian country worked on each band.
Total score willbe the sum of prefix multipliers of each band
multiplied by the sum of the contacts points on each band.
7. Logs (A) all times in GMT
(B) £ill in prefix or country first time contacted,
C) use a seperate sheet for each band
D) Mail to, JARL Contest committee
Central PO BOX 377
TOKYO , JAPAN
Before 30th November 1973
# sk m % % % ok % %
CONGRATULATIONS THIS MONTH GOES TO
JOE 7Z2GJd and PHIL on the birth of their first child, a daughter
CHARMAINE IOUISE.
GRAENE 7ZGT and DIANEon the birth of a daughter KAREN LOUISE.
And to MIKE WILSON for his 21st birthday.
* ok ok % ok %k ok % %
After the dinner in Hobart certain gentlemen patronised the Casino
till 3,00 AM and recovered some of their weekend expenditure.
Norm 7NR put his key into the motel door at about 2.30 AM attempting
to open the door when the key broke.
Ten minutes kicking on the manager's door produced another key
from a character dressed for a cold winter night in long johns,
woolly vest and no socks, but suitably insulated internally
against influenza HAPPY DAYS. 7NR
ok % % %k ok %k %k %
Don VK5BM/MM has been active on ch.l during last weeke.
I was silly enough to take up his invitation and visit the '"shack"
68000 tons of it, and 750 ft long.
I came away with three impressions, one, you need to be a UNI type
to drive such a shack, two, Sailors haven't changed and three,
"Duty Free'" tastes better.
His Jjob would suit an old codger like me, five months leave a
year and a fair wollop of db im salarye.
7NR
*ok sk sk W %k %k
AT AT T3y
4 -IJL:J - ‘,
A 250 1% TRUANCY COUTTAR
e .....__ DART 4 -
|
Crystal Oscillator, 2 Chain, Strobe and 2eset Pulse Generation
A5 mentioned in DART 1 of this article, some means must be ‘emplored to
open and closc the count gate accurately, ”wi: is done in this instrument by
first starting with a 2 1774 crystal osecillator and then dividing its output
dowmn to obtain the required control »ulses for the count sate. The strobe and
1 4 33 o&Y ; T4 N 2y
reset rulses
.
are also sencrated
o
from the timebass chain.
The heart of the instrument is oscillator, as shown in Fig. 7.
This uvses a quod tro=intut " IATD" zat cnly tro sections are used in
the form of o »air of inverting amlifiers wvith the crystal in the feedback
path. “he cepacitor/trimmer comnected in series with the crystal allows for the
adjustment of freouvency against o standard such as 7,7.7. or some other
frequency-measuring device of kmowm accuracr., The crystal used is a D type, with
a .003. adjustment tolerance, Al-cut t.me, specified for overation at ambient
tomperatures. The crystal was purchased from I3 Pty. Ltd. and the 1Ya designation
for this type of crystal in torms of tolorance and stability io cless "P,E,7."
with the holder code "712a" and the nominal intended ghunt canacitants of 307F.
For maximum stability the capacitors in sories with the crystal and the tw
sections of the 7400 shouid be of sood aualitr,
As we require theinput of the timebase chain to be 1 172 we must f'
}_l. 4
D"
divide the output of the crystal oscillator by two. Thig is d
©
ced
r*a
s
o=
0
o
'O
7473 dual J-7 flin-Tlop, boih as an osciLlfl;0r bulfer and as the 1n1tal 21
divider. 3Both flip-flo s are connectedin the togsling mode and operate from e
the 2 Y43 output. (ne scction nroviiin~ en effectively buffered 1 774 output
and the other »roviding an indepeondent 1 7774 signal for the following divider
chains :
+5v
7400 PIN 14 = 48VealS I® 1| MHZ CAL OuTpuT
M_Z__*ND
TZB DiVIDiER Ci/AIN
WO SECTIioNSCF 7hc o
)
U a0l Angust 73
vage 7
TRATTT LT A & YA ad S . ..
IACTIICAL
AN A ANTICLE
SN 083 (Jontdj..
Timebase Chain
The divider chain consiats of six 10:1 divi der decades {7490s). The
first four do nothing else but divide by ten and so »provide the outnruts necessary
to the gate control circuitry. ‘"he next two decades, as well ag providing
outnuts forgate contrel, also provide outnuts for strove and reset pulse
generation. (ne requirenmcnt that needs to be nme t ia that the strobe rulse be
gencrated before the reset mulse. If this condition is not met the main
counting decades will be reset to zero hefore their outruts can be displayed.
How this effect is stopred All hHe shom in the write-up on the main counting
wecades.,
Strobe
ie L
and Reset
ee
Pulse
AT
Generation
TR T T P A e »ared n»n“%mm.
»w.-qrm-n v S 00 et e ey s o »
1 ve have a choice of two sanpling rates, one per-second and ten ner second.
{ Phis is selected by switch 31, which is a trinle nole twoe position switeh.
$ebtion A" celects the o output of the corrsct half of & 74H20, a dvual four
“inmut "oD" gate. 3ections "3M and "ot nelect the correct outmuts of the last
two decade counters for reset pulse gereration. A3 already mentioned the
strobe pulse must be generated belore the roset sulse; just how this occurs is
as followss:
e will only have to consider the.last two decale counters, nas these are
resyonsible for the generation of these pulses, As the input frequency to the
5th docade is 100 HZ (10 17/3) there will be a »nulse at the innut every 10 m/s
and the four "BCD" outouts vill change at that rate in the l=2-4=2 DCD code.
The four outputs are A =1, U =2, C = and ") = 3, The truth table helow
o
indicates what outputs are at Losdce 1 for 11v nunbar of inputrulses.
Fulse 17 s .
0
OO0 HEHOOHKFOO
1 If we exes -ine the truth table we can select
2 the neccessary conbinntions that will meet
5 the reauirements of strobe pulse renaration
4 before reset ~ulge generation. Nrouging the
5 coont of 7 (L4, 08, and 2C at 50”10 niny for
6 strobe ani the count of O (A ! \ l at logic
! nimy for reczet, this requirement is met,
8
9
0
¢n the count of seven, the three no~ic nin ontruts {4, 3, and ) nake the
\
innuts of the 74720 go ! .y 50 roduci a low outrut, Breause of loadine of
the devieces uczedin the mein coun idne uGCRueS to store comted ~mlses is too great,
we nmustprovide some meang of buffering and also invert the logic "O" outmt of
tne 74720 to logic "1, as a logic "1" is required by the device to command it
o store the outrut of the nain cmumting decades This is done by using a TiX
IEV:ZT"“ (747104) which provides the necessary bufforing end inverting, Taving
now stored the erunted signal we must now reset the counter back to zero before
the comnt pate again onens. This is done at the count of nine when the outruts
A end QD rise to logdic "lv, The logic 1M outnuis are apnlied o the two
cates o.fi of a2 7400 via the sampling rate o itch S1 scetions n and s e 7ith both
gobes high the outrut will be low.
z T CF T3 T T g0 7S A TAS st 73
-
nae
DECITIICAL ARTICEE (CONTe)eenves :
StroveandesetpulseConcration {Cont) L
Ao this cutout is of the wrong logic levelwe must invert it. This is done by =
another -, soction of thecame 7400 used to combine the A and 1D outruts of the
: aecade counter used for recsettine. The output of tiis uvctlop is av~lied to
’ two goates of a dual 4 inout Schmitt Trigger (one half used), This Schmitt
Tripger will orovide the correct hvlse shane recuired for the reset line., The
ffh output of this chnmitt Trigrer then feeds a number of scctions-: they are the
i gate control 01r01“ur" the main counting an’ subtracting decades via a dual
MRAKD" vower gate (7440) and to the overflow fli-flop via - of a 7400. The
T44D ig required because tiie loading of all %iic resct pates in the decade i
: counters and gate control would be toc great for the 7415 Schritt Trigeer, The 2
section of the 740U ig reqguired for the cvorfiow flip-ilop because it requlrvu
a logic "O" for resetting. The circuit of the divider chain and control nulse
generation anvearsat My, 8. :
G, 8
T LUN20, fale 268, 1413 i/ --
j__.sr_uz_»"_g_.,u,,_-_i-.__z- U ey !
Zigo 15VolspivS, GNP pin 0
—
O [PRR
i '
STR03E pulsE
OuTpul 7O 4AIN
|’>)—‘)‘I~ CoucnmiTing DEcadIs
! v
SIA-C= Smggfl‘ /’:9/_1{[ Po54 - iofSéc
&cu— T LfSee
=
k.
e
-
5
Moy
BULILETIN OF THE - £
‘oo Fla
maQ
LitiDe August 1973
reprinted from AELA Page 9
SOLID STATE SWITCHING FOR THAT 2 NoTTEAMPLIFIER--Basil Barnes VE6BB
I f you 're buflding yourself amplifier for your 2 metre rig-- an
whether it's a tube type or semiconductor type--you're a
going to come to the problem of how to switch it in and out of
the circuit in the transmit-receive cycle. Here, naturally, I'm
referring to the placement of an amplifier after a transceiver.
It is possible to use relays, but they are bulky; they .require a
switching voltage (keyed to your PTT, no less); and they're prone
to failure especially when it will doe the maximum harm (Murphy).
The following circuit is very simple, foolproof in normal operation,
and allows instantaneous switching by RF. sensing:
D |
Iw 4 | i ¥ auTteuT 3 ANTENN A
- THINFUT fifl.mi’l..meflf.
All dicdes are " "; {\ g * i
s !
siicon {jP‘z /NQI?
i
Each phas (g s i
i
®< A
i. {I‘}L .6o& =l
14 3/.(_“ lonfl of o
L)
g
RG 174 u ‘ mAraler K_“u,\ e
Thes may by coled wp and taped outr 7
ob the Oy
Theory of operation is easy to understand. On receive the silicon
diodes, with a conduction threshold of from .5 to .7 volts do not
conduct so the received signal passes from the-antenna to the
receiver by-passing the amplifi &I 4 There is virtually no signal
loss on receive.
On transmit the silicon diodes at point A conduct and ground that
point of the coax (i.e. short t he centre conductor to the braid).
As the coax is quarter wave-i ength (allowing for the velocity
a
factor of the coax), then the input end appears as an open circuites
One of the properties of a quarter wave-length transmission line
shorted at one end! The signal! voltace then overcomes the threshold
of the silicon diodes and is applied to the input of the amplifier.
At the output the same effect applies and the signal is shunted out
to the antenna! Result is an amplified signal with no interaction
with the input circuit.
However it should be noted that if the amplifier is not wanted,
“then it will have to be switched manually out of the circuit with
switches or relays. This is a very small price to pay for such a
simple performer.
I built a solid-state ampl ifier to follow my TR-2200, with 20
have
Watts output. The compltete amplifier.is built into a minibox with
7 e
the dimensions of 5" x 3" x 1" {minus the heatsink). The 12 volts
to the amplifier need not be switched as there is no drain at all
without RF excitation.
-l am toying with the idea of placing a receiver preamplifier at
point A to give a more usable s ensitivity. Judicious choice of a
drain load resistor may enabile the preamplifier to be left on, but
to receive virtually no voltage whi'l e the amplifier is drawing current.
SailelMa
BULLETIN OF THE NORTHE RN BRANCHES Wa.leoAe. TAS. August 1973
Page 10
reprinted from Westlakes Radio Club - Newsletter.
¢ 7 AN _EXPERIMENTAL DIRECT COXVERSION RECEIVER FOR 80 MET:UES. ~ D.Crofts,
The circuit described is a rclatively simple form of a direct- conversion type
receiver. The basic version consists of an R.TF., amplificr, feeding.directly
into a balanccd mixer or product detector - with a tunable carrier insertion
oscillator at the signal frequency, followed directly by the .audio stages and
without any form of I.F. amplifier, Provided that the balanced mixer is truly
linear, then the effective selectivity is governed by the bandwidth of the A.F,
circuits j thus climinating the necd for cxpensive crystal and mechanical filters,
Such a basic configuration can be extended to A.Ms and D.S.B..rcception =
with substanticl thcoeoretical advantages over the use of enwelope detection =
provided that the local osgcillator can be locked to the frequency and phase of
the incoming signal, L1 interesting possibility is that of developing simple
transceivers, sincc the local oscillator on the signal frcquency, could be used
directly as the transmitter V.F.0. without heterodyning.
PRODUCT.DET/CTOR. r——~——~——~__4 +12V L1s Coil wound on a
. » Ducon F4040/2 Toroid,
< 680" outside diae
Q2 material with 10 x
«010 hoolkup wirce
<01 Audlo ¢1; Variable type at
I about 365 pf,
18 turns
AT " Out,
MPF121 connectdons
as shown fromn abovc,.
i o 16ul
turng lo01 |~
4 turnd ,_m%__,L____l_,__f‘-12v
-)
———————————————————————————
e
Figc1 _Q_S_c___Ingut
The receiver Figure 1, features solid state circuitry and will enploy
Mosfet ICys, and discrete transistors, Although the list just shown nuy appear
expensive, it is cecrtainly not so, because componants chosen for use were the
lowest priced in their class, consistant with performance, The rcceiver will
be presented in 3 main nodules, so that the constructor can determine for himself
whether to omit a section or include it, The Oscillator, shown in Figure 2 is
a tuned-gate type, with a drain fecdback winding,: no buffer is employed. No
attempt has been made to regulate the actual oscillator power supply.
It e AN —-——9 ,
5 turns :EéM, 4700hns +12V ‘ pflPF
s . Fig.2 o2
! 68pf g/ | > feef To
; i '-”'”“”"T"’”“1 —_ Product
4%" urns | . . ~— S DL?teCtoro.u’.n 1
12" longy - C1 %4 7 D) kCT
(g" ferrite ”"365pf§ Mpf102| T -2V 5
rods 7 — — —
o om 4 ®
- @
BULLETIN OF THE NORT HoRN BRANCHES W.I.A. TAS. August 1973
Page -11
AN -D}PERIWQJTuLDIRBOT
ale i e
COuVELLS LOW HECETVER 3 PART 2.
The soccond nodulc to be shown 1s the audio Piltsr, The filter is of the active
type with fcedback via a Twin=T nctwork. Threc bandwid‘th positions arc available
which aree 800, 160, 800, 60, 300-3%500 (plus or minus) Hz, Thesec bandwidths
cater for _ both CU and phone, is.varied by placing damping rg¢sistors
Bandwidth
across the fecedback network, Power requirements are 9 volts at o715 nfl;\¢
;: 1000pf 1000pf X
""f“"‘" ’f -_— -”wnx-.-—-———~e
100K ‘ XL
-qu___ l
2200pf | 1. hone= )QO-)5OO Hz
4-_../\/"/'\'./‘\’._ ANV - 2e ColWeom &005—160 Hz
220K 220K 60 Hz
%, Co\le=-300+="
Y + Position 1. 100K
Wh—p " 2, 2,21~
Inpus . 5ex * ; 4?Kf~"m_—"_Jl oo ' o AN
051%4' f;‘_mwé_fi‘@ 2, W 4TuF
i
g ful
<L ‘ ‘ 741 t—|[——o Output AUDIO FILTER
- ! 3 '
. <+ ‘g
56K 3o l-: ’ J.
= - o st
ed < 4 Tul / / h e
T 6.k \ Lo\ Top WEw
D 5 7/“
,.__A_L————-L-—IT—_.—_——‘{?‘M¢ 9V .‘.\\ » f Conncctions
— \.A-,
4s shown in the circuit ciafran, the circuit uscs a 741'IC, that is usec o Fair-
1
schild ul741cy dational LIT7/41ch, Motorola MC1741Gand so on, Unfortunately,all
I can tcll you about the IC ic that it is an internally frequency coupgnbated
.operational annlificr,. You sound surpriscd ! 3y ncxt nonth I will have all the
blurb »n the IC, including Lnturn L 61rcu1try and will publlsh 1t thefi.
I hawe=Tocn inpresscd with the ilters performance that I hTVL ncrnan@ntly
oy
0y
installed it in Ly nain recciver = a Superhet - and intend to build angxhor one
for ny direct c-umversinm receiver, If a uorse signal is tuncd in, the phone
‘
"pesition is covered in static. When it is switched into the CW bandwidth the
signal buconcs 2 purc aulio toney with no ~tatic orinoisce My thanks to Janie
Canmpbell for verifying the results I have achieved,
Next Month s High ;o in audio amplifiers (o nd, hopcfully the 741 IC data)
N
-’Ol/febblb 2y nmistake crept iato the conncections for
N
s the MPI' 121, last nonth. 'The corrcct
.Defim/<q
connections are shown opposite,
| MPF1<
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PLEASE NOTE NEW ADDRESS & PHONE
NORWINDS :\55\
= i
ELECTRLICAL ENGINEERS ¢
. VSPECIALISING IN MOTOR REWINDING AND ASSOCIATED WORK
“r ' _
e - 27 SUNCREST PLACE, RAVENSWOOD
' TELEPHONE 391515 o
- __* oo koA o e sk sk sk % kook ok o ok ok ok ok % %k ok %k % % K ok ok
e
JOE VK7ZGJ has the following for SALE
- ,
AWA MRT 25a carphone with xtals for CHe B, 4, 1. $1 30,00
VK3 , 432 Mhz converter double conversion w1th xtal $18.00
- IGL 6 metre converter with xtal - < $12.00
PYE Mk3 with FET preamp, xtals for 53.032, 5W out $121OO
55 Mhz crystal filter, circuit and components ‘
to built an SSB execiter, inecluding upper and
lower sideband xtals $10.00
No 10 xtal ealibrator unit $ 8.00
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