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G8MNY > TECH 06.06.21 18:28l 254 Lines 12580 Bytes #999 (0) @ WW
BID : 36666_GB7CIP
Read: GUEST
Subj: A Simple V.O.X. Circuit
Path: IZ3LSV<F1OYP<DK0WUE<GB7CIP
Sent: 210606/0803Z @:GB7CIP.#32.GBR.EURO #:36666 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Sep 09)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Here is a 3 transistors 6 diodes circuit that is a Voice Operated Tx PTT
control as well as an ANTI VOX circuit to stop mis-operation from Rx noise.
SCHEMATIC
ÚÄÄÄÄÄÄ¿ÚÄÄÄ¿ÚÄÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄÄ¿
>Ä´ RFI ôMICô AF ôSet Decayô Set ô LEVEL ô Set ô AF ÃÄ<Rx
Mic³Filter³³AMP³³DETECTOR³³ Time ³³Level³³COMPARITOR³³Level³³DETECTOR³ LS
In ÀÄÄÄÄÄÄÙÀÄÄÄÙÀÄÄÄÄÄÄÄÄÙÀÄÄÄÄÄÄÄÄÄÙÀÄÄÄÄÄÙÀÄÄÄÄÄÂÄÄÄÄÙÀÄÄÄÄÄÙÀÄÄÄÄÄÄÄÄÙ
ÚÄÄÄÄÄÁÄÄÄÄ¿
³PTT DRIVERÃÄÄ>PTT
ÀÄÄÄÄÄÄÄÄÄÄÙ
CIRCUIT
VOX TIME VOX GAIN ANTI VOX Smooth
+ÚÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÂÄÄÂÄÄÄÂÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÂÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄ<+9-15V
100u === _³_ 2uF³+ ³ ³ ³ ³ +³10u _³_
_³_ D1\_/ === ³ 220k ³ ÚÄ>10k === /_\ D5
ÃÄÄÄÄ¿ ³ === VAR ³ PNP³/e POT ³ ³
³ Ge_³_D2 10k ³u1 ³ 220k<ÄÄÂÄÄ´ ³ ³ D4 ³+10u
10k /_\ Ge³ ³ ³ POT ³ ³\ ÀÄÄÄÁÄ´>ÃÄÁÄ´ÃÄÄ47RÄ< LS
ÚÄÄÄÄÄ´ ³ D3 ³ ³ ³ ³ 10M ³ DETECTOR
³ ÃÄ´ÃÄÁÄ´<ÃÄÁÄÄÁÄÄÄÁÄÄÄÄÙ ÀÄÄÄÄ(ÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄ> PTT
10M ³ u1 DETECTOR ³ ³ ³
³ ³/ 4k7 ³/ BC107 _³_
ÄÄ´ÃÄÁÄðÄ´ BC109 ÃÄÄÄÄ´ NPN /_\ back
u1 FB ³\e 4k7 ³\e D6 ³ EMF
MIC ³ ³ ³ ³
ÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄ< GND
MIC AMP PTT DRIVER
All diodes are 1N4148 or Germanium point contact type.
HOW IT WORKS
The BC109 Mic high gain amp is RF protected by the Ferrite Bead on the base
lead. Its' low level output is voltage doubled with Germanium diodes D2 & D3
into double time constants Caps to give fast attach & slow decay time
responces. The rectified DC is referenced from the +ve rail less the voltage
drop of Silicon diode D1 together with the germanium detector diodes, this
makes the Mic Audio detector very sensitive! The voltage is put across the 220k
VOX gain pot, & the hang time determined by the 220k decay variable control
that discharges the capacitors.
The gain controlled sample of the DC switches on the PNP which turns on the NPN
PTT drive transistor, that is protected from rig relay back EMF by D6. The 10Mê
from the PNP base to NPN collector, gives positive feedback hysteresis if
needed (SCHMITT) for snap on-off action.
High level LS audio is also voltage doubled with Silicon diodes D4 & 5 to give
DC that feeds the ANTI VOX control, this DC is used on the emitter of the PNP
SB HOBBY @ WW
Re: regular packeteers on air
By G8MNY (Updated Nov 20)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
A long time back Andy, G0FTD wrote:-
> There's a surprising amount of true on air activity from some packeteers that
> we obviously don't hear enough about.
So here is MY BLOG
I have done a lot of amateur radio operating & construction since I started in
1977 with the B licence. (actually passed the written RAE in 1970 self taught
while at college, but too busy with that, work & discos etc. to take it up.)
NO CW
I was not interested in the 150 year old CW mode, I am not musical at all, so
learning CW looked too hard to do for me.
§=Â=Ð==Ð=¿ -. - .-.- ??
ÀÄÄÄÄÄÄÙ
So I strove to do more technically challenging modes like ATV, where home
design & construction was the norm.
PACKET
I have been active on packet radio for over 30 years, started with YAPP
software. Now still do it with RF...
____________ _______ ______ ______ \|/ Loft
³Compaq W98seÃÄ´TNC 220ÃÄ´FT290RÃÄ´30W PAÃÄÄÄÄÙ fullwave dipole
³ PaKet 6.2 ³ ~~~~~~~ \ÃÄÄÄÄÄÄ´ ÃÄÄÄÄÄÄ´ |12v PSU &|
~~~~~~~~~~~~ ´FT790RÃÄ´10W PAÃÄ>Chinmey X500 Colinear | battery |
~~~~~~ ~~~~~~
I am well known for my ASCII art, in technical bulletins, that I publish on
packet radio, this I do to try keep the mode more interesting. These I allow to
be freely copied to Ham WW internet sites.
ACTIVITY _____________________________________________________
My level of activity, | | | | | | | | | | | | | | | | | | | | |
since 1997 I have filled | | | | | | | | | | | | | | | | | | | | |
20 full size log books |1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20|21
with main station & /P | | | | | | | | | | | | | | | | | | | | |
activity, not incuding | | | | | | | | | | | | | | | | | | | | |
/M operating! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DX
My best DX ever, was years ago in 1983 with a confirmed SSB contact to VK on
70cms /2m via OSCA 10. ____
_ - ~ /G ~\
_ - ~ 70cm up | |
Osca10*= ~_ | EARTH |
~ - _2m down | |
~ - _\VK _/
~~~
<8000miles>
< ---- 23000 miles ---- >
Although using a satellite may be seen as cheating by some, my 70cms LSB signal
had to go 23,000 miles up to OSCA 10 when it was just on/below the horizon.
Then through the transponder to 2m USB, then another 23,000 miles to again
another earth scraping path to the VK. The rare 10 min window was only possible
a few times every few months!
ATV
On the ATV front I often used to run fast scan TV with a 400W PEP Vestigial
Side Band colour on 70cms from a homebrew Tx & homebrew K2RIW PA. I worked
stations in full 625 line PAL colour ATV a 100 miles away.
_______ ______ ________
|12V PSU| |ATV Tx|---|K2RIW PA|-----¿
~~~~~~~ ~|~~~~~ ~~~~~~~~ \__________70cm beam
__Ú---¿ | ___ _______ Relay/ LDF 450 & rotator
()_|CAM|-----/ |[ ]|---|PREAMP |----Ù
À-Â-Ù ~~~ ~~~~~~~
/ \ 70cm TV
Later I moved most ATV activity to FM on 23cms, but with only a 40W homebrew Tx
& PA when GB3HV repeater started up 51kM away in 1987. I have been one of the
main players in the Home Counties ATV Group since it formation in 1980, serving
as club secretary for many years, & I can still be found at rallies on the ATV
stand.
/P CONTESTING
I have also done a lot of /P contest from the hilltop @ Woldingham (sometimes
under G6CTU or other calls on 2m 1988-1999) working mainly on VHF/UHF both ATV
& SSB modes with ERPs of around the 40kW mark from large aerial arrays at 66ft
& I designed & built much of the kit for this.
o_o_o_o_o_o_o_oo²
70cm 27el ×
Quad Loop Yagi º 400W
/-/-/-/-/Â/-/-/-// @ 66ft º
/-/-/-/-/Â/-/-/-// º
4x 17el ÃÄÒÄ´ 400W º
Boxed ÃÄ×Ä´ ×
/-/-/³/×/Á/-/-/-// º
/-/-/-/-/Á/-/-/-// º
º º
2m beams º º
@ 50ft × ×
º º
º º
º ÚÄÄÄÄÄ.-Ä-. º
º generator |Operating³ º
Rotator² [] |Tent&³Van³ Rotator ²
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 4x 17el was soon replaced with 2x 17el @ 55ft & 66ft due to the work needed
in putting it all together /P, but it was VERY nice to use a 20dBi gain aerial
on 2m!
SUMMER CAMPS
For many years I have supported the Caterham Radio Group Summer Camp GX0SCR/P
in Oxforshire, active on 160m - 2m. But when they stopped, I have gone on to
support the 8 day Wimbledon & District ARS Summer Camp on Reigate Hill GX3WIM.
Active on MF HF SSB 400W & QRP, as well as QRO on 6m, 4m, & 200W on 2m FM/SSB,
& 2m packet link to Caterham 70cms for Dx cluster & the ww conver chatnode ch
11. Very large aerials are put up e.g. 2m 5/8+5/8 colinear/11el beam, 6m 5el &
3el HF tribander @ 40ft, 80 & 40m wire dipoles, G5RV, 70m of long wire @ 40ft
for Topband & Xtal set, a 4m end fed halfwave @ 10m, & a 2m 9el beam @ 54ft.
The station is located near Reigate Hill IO91vg in a cow field.
DEMO STATIONS
Also been /P for many demo station both ATV, VHF, & HF etc. with SCOUTS, GUIDES
RAFA, OFCOMM, CLUBS, RALLIES, SUMMER CAMPS etc.
/ / /
/-/-/-/-/-/-/ 80/40m trap dipole /----/-----/
17 el ×--------=-------------Â------------=--/----/× /
2m º | 3el HF º
beam º | Tribanderº
@ 66ft × | @ 66ft ×
º | º
º | º
× /\ | ×
º / \ | º
º generator |Demo|| º
Rotator² [] |Tent|| Rotator ²
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
HF AT HOME QTH
I have grown VHF & UHF aerial systems over the years & have/used to have up..
2m Loft full wave dipole (packet),
4m dipole @ 25ft,
2m & 70cm X500 15ft tall colinear @ 35ft
2m 8el homebrew Quad @ 40ft
70cm 19el Tonna @ 41ft
24cms 24el Tonna ATV Tx @ 42ft
23cms 55el Tonna ATV Rx on 2nd mast @30ft
70cms 55el fixed vertical beam (ATV repeater command)
Since class B's were given access to the HF bands, I equipped my shack with an
HF rig now IC735, & the garden with a nest of HF dipoles & a squeezed in a
topband dipole over the house too.
Houseúúú------------------------------o----------------------------------úTree
Chimney 80m 40m~ ~ ~ ~-~-~-~-~/º\~-~-~-~-~ ~ ~ ~
+15m 20m ~~~~ º ~~~~10m
feeder
But my HF interest is not as high, all too easy rubber stamp QSOs etc. I have
had a brief go at PSK31 as well, but again not that interesting really. So ofen
to be found nowadays in afternoons natters with 400W on 80/40m. As my health
has affected my tong, I try to have many QSOs in the afternoon, to keep it well
excersised. (before much of the neighbourhood QRM starts up)
TRAINING
I have also been involved in training (on air & tech side). At first just a 1
day break a year from the normal lecturer on the original full RAE courses, &
later with Novice & now the M3/6/7 Foundation & 2E0 Intermediate & Advanced
courses, at the Bromley club. And also once @ RSGB HQ for their staff. Our club
has had over 300 students of all ages youngsters to old timers, with a good
pass rate.
So ask yourself "what have you done to bring more people into amateur radio?"
CLUBS/SOCIETIES
I am member of B.A.T.C. (UK ATV), Home Counties ATV club, R.S.G.B. (UK Soc),
Bromley & District ARS (Mainly Training), Caterham Radio Group (Mainly packet),
Surrey Radio Contact Club (based in Croydon where do monthly "Fixit nights" &
VHF NFD) & Wimbledon & District ARS. I often give talks & help out with demo &
/P activities to these clubs. There are loads of other clubs locally I could
join too, but enough is enough!
How many clubs do you actively support?
COMMUNITY RADIO
On a different tack, since 1994, I offered my radio expertise to a local
broadcast Restricted Service Licence projects (28 day max), 37 done so far.
Normally they are 10W ERP Vertical pol on Band 2, full spec stereo & RDS, with
band 1 or band 3 VHF links & sometimes live O.B. systems as well. Also 6 AM
ones done on 531kHz, with a wire aerials that are huge, but still tiny compared
to the wavelength! Now SUSY RADIO is on its 2nd 5 year licence for 103.4MHz &
there has been loads more work done to get it all through the Ofcom technical
inspection etc. See old photos & listen on www.susyradio.com
I see this as another way to "put back something into the community".
See my technical/bcast buls on these subjects.
Y don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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