SKM C450i24093017033
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THE MONTHLY BULLETIN OF THE WIRELESS INSTITUTE OF AUSTRALIA
NOVEMBER 1966 TASMAJTIM DIVISION TECHNICAL ARTICLE
AN ADD-ON NOISE LIMITER by Lee Cordell and G-reg Johnston.
Input fi"OBi •••--- ••
Audio
01
OA202 47 K Volume Pot
I—''VNAAA ''V\A
^ i
$^7OK <
^l.-330pf
Either AJT or ^47OK ^1.5-1- ^330pf- <"
?" 'I M' 1
roduc-b Detector. -.)....-
+
'•, A/VV<—/•\^/(^—- -
1 uf lOKpot
M'-I_ ^lOOK
^
^ Level Adjust Po-fc.
RX B+
OA91 or similar may "be used. bu-t no-fc recommended. Silicon Preferred.
Wi-th the unforl. unate wealth of hefty lumps of noise 'bothering q.ui-te a few, as
is obvious from the frequency with,which complaints are heard on the Sunday call-
back, -the circuit and comments following c.ould prove of interest to quite a few.
As can be seen, the limi-ter can ~be made 'up on a su'b-chassis and provided you
can find room on the front panel for the single con-trol, all you need 'to do is i.nsert
the unit immedia'fcely in front of the grid of the first audio s'tage of your receiver
and. leave i-fc in circuit.
The"cliFpingtl level of -the device is con-fcinuously adjus-table from zero -bo "very
appreciable" with -bhe circuit values and po'tp, nt;iometer shown.
As anyone who has aver -tried -to beat the noise with an audio noise limiter in
one of i-ts many forms knows, the results vary from "CToB«Go" -through "just efifective"
wi-fch -the 'best T3ein.g"not 'bad". With this particular circui-t -the performancse comes
into the "not bad" category where by far the greater propor-fcion of the really otoject-
ionable hash is muted, down to an accep-fca'ble level and is -the best ye-fc as far as either
THE MONTHLY BULLETIN OF THE WIRELESS INSTITUTE OF AUSTRJ'iLIA
NOVEMBER 1966 TASMAI^IM DIVISION VHP SUPPLE1IENT,
PYE VHF MOBILE UNITSo
It has been brought -to the a-fctention. of the VHP group by Rick, VK7ZAT, that the
modifica-tions given in AE for toth crystal and tuneable receiver will not work when
-the uni-t has 3mos xtal in the RX Osc. However, by adding, ano-ther trio&e stage-
as a -tunable osoil. l at. pr, it will work and very well -boo.
AT the las.t meeting of the Group, a fox . hun't was''held.. As there was c[uite a bi-t
of business -bo attend -to, -bhestar-b was'delayed, somewhat, much -to -the agi-ba-bion of
Wins-bon, 7WH, -who wished', pick up his XYL. No wonder he wanted to -bake par-b» I -fchink
he must have known something no-one else did., because he -burned round sjid won it: IS
We hope -bha.t in the near future there will be 6. new call signs in the Hobar-t
area, subse<iueni; -to the October CW exam. At ^his. stage I will not mention any names
-to save embarresment if -the results turn out to be not all we could wish for. However
I am confiden-t tha-b you all made i-b fellas.
ZL VHF FIELD DAY.
This event will -bake place on 10-bh and 11-th of Decem'ber and as in past years,
the Kiwis will be climliing hills and moun-tains looking for DX, so keep yours ears
in the speaker and the 'beams Eas-b over that weekend..
On -the 7-th Secem'ber the Ross Hull Memorial VHF con-fces-b begins and -this year
logs will be en-tered for the best 7 days. The Rules should be appearing in AR any-
-time now» All the bes-t to you all. Lets see what the Tassie boys can do -fchis year.
NORTH -(UTO TORTH WEST ZONE NOTES. Thanks to Sandy, VE7ZFL ajid Tony, VK7ZXT.
Tony, 7ZXT and. Frank, TZW are Tso-bh. active in Smith'-ton using Pye Reporters on
-the VK3 Ne-fc freq.u, •of 53. 032 Mcs 'but anticipa-te changing -bo . 035 in "the future.
The pair are using ^ wave whips on their cars at the moment, Tsu-t are making
inves-fciga-fcions into the cons-bruc-fcion of small collapsible beams for por-table and
T)X use Tonv and Frank are looking ou-fc for con-fcac-bs along -the coast and would like