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G8MNY > TECH 01.09.16 18:41l 224 Lines 11415 Bytes #999 (0) @ WW
BID : 16555_GB7CIP
Read: GUEST
Subj: RTT Comms Test Set
Path: IW8PGT<CX2SA<N0KFQ<GB7CIP
Sent: 160901/0620Z @:GB7CIP.#32.GBR.EURO #:16555 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Nov 14)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I bought this large test set in it's flight case, at a recent junk sale. It
looked very smart & could do quite a lot. It came with an Operating Guide, but
no service information. (nothing on internet)
___________________________________________________________
/ /|
/ / |
ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ/ |
Þ /__________________________________________________________/Ý |
Þ³ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿³Ý |
Þ³³ÚÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄ¿³³Ý |
Þ³³³ \ AF ³³ \SINAD³³ 5 6 0.0 0 0 0 0 0 ³³ \MOD ³³ \POWER³³³Ý |
Þ³³³__\____³³__\____³³___________________³³__\____³³__\ ___³³³Ý |
ÚÁ³³o _ _ _ _ _ ³³Á¿ |
³_³³ (_)_______(_) (ú) (_) o ø ! ! ! (_) o ³³_³ |
AF³³o _ ³________³ _ _ _ _ ³³ |
on³³o (_) o o (_) (_) ! ! (_) (_) (_) o ( ú ) ³³RF /
³³CTCSS SELCAL MOD _ GEN FREQ ú_ú _ _ _ ³³in/
³³1234 123456 12 (ú) 1 2 3 4 5 6 7 (ú) (ú) (ú) (ú)³³ /
³ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ³/
~~Þ²Ý~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Þ²Ý~~
SO WHAT IS IT?
It is VHF/UHF RF Transceiver test, set with all of this in one Box...
Dummy Load.
Power meter.
Frequency Counter (very accurate).
PLL RF Signal Generator (7 Decimal Thumbwheels).
PLL CTCSS tone Generator (4 Decimal Thumbwheels).
Selcall ID Generator & Decoder (6 Hex Thumbwheels, but no PCB, so removed this)
AF Oscillator (Wayne type, but unusually controlled by 2 Decimal Thumbwheels!)
AM/FM/PM Rx (Automatic Scanning Rx).
Modulation Meter, +/- Peak reading.
SINAD Meter (AGC & 1kHz Notch, for Rx Sensitivity & Distortion measurement/adj)
AF Volt & dB meter (level & frequency response checks).
IF Xtal Oscillator. (Xtal tester & IF reference Output)
SPECIFICATION
Power AC IEC Mains input 230V/115 @ 60W or 12V DC @ 4A.
RF Input N socket 50ê 40dB Load atten. Max 1kW peak, 50W continuous.
Power meter 1W 3W 10W 30W 100W 300W (RF detection Counter & Rx switching)
Frequency Counter 9 digit 1Hz-560MHz in 3 gate times & averaging to 1Hz.
Freq Reference Accuracy < 1/10^7/month, internal Oven Xtal reference.
Signal Generator 100Hz steps 60MHz-560MHz, PLL type (OK @ 10MHz).
Attenuator 0-9dB +7x 10dB steps gives 1.8uV-50mV before 40dB Load atten.
AF Meter 0.25mV - 10V FSD, with dB scale.
Pilot tone(CTCSS) PLL 10Hz-999.9Hz Mod Level adjustable & Counter Decoder.
Selcall 6 char, Mod Level adjustable & Decoder.(No PCB)
Modulation AF Osc 100Hz-9.9kHz or external, Level adjustable.
AF Meter Bal/floating input, 3,10,30,100,300mV,1,3,10V 11Hz-27kHz -3dB
SINAD meter Auto level, 1kHz Notch, 0-20dB/0-100% Noise+Distortion.
Modulation meter Auto Rx. +/- peak, AM 50% 100%, FM 5kHz 20kHz, PM 2Rad 5Rad.
Rx AF Filters Comms 300-3kHz or HiFi 50-15KHz -3dB.
SCHEMAIIC (reverse engineered)
_______ ________ ________ _______________________
AF:ÄÄÄ´Bal AmpÃÄÂÄ´Range SWÃÄ´AF Meter³ MainsÄ´PSU +26,12,10,5,-12,-20³
IN ÀÄÄÄÄÄÄÄÙ ³ ÀÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÙ 12V__/ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
_______ ³ _______ ________ ___________
:ijIF Xtal³ ÀÄ´AGC AmpÃÄ´Rej 1kHzÃÄ´Sinad Meter³
oÄÁÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÙ Ext Mod
__________ ________ link ___________ _________ o ______
RF ³Dummy Load³ ³ Relay ÃÄo--oÄ´ Switched ÃÄ´ PLL Sig ³_/ ________³PLL AF³
IN o´AttenuatorÃÄ´SplitterÃÄÄÄ¿ ³Attenuators³ ³GeneratorÃÄÄÄÄÄÄÄÄ¿ ³ Gen ³
OUT ÀÄÄÄÄÄÄÄÄÄÄÙ ÀÄÂÄÄÄÄÂÄÁÄ¿ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÙ ÀÂÄÄÄÄÄÂÄÄÙ mod³ ÀÄÄÄÄÄÄÙ
RF³ rly³ ³ ³ _____³_ _³_ ³
___________ _³____³_ ³ ÀÄÄÄÄÄÄÄÄÄÄÄ´ Freq ÃÄ´Ref³ _____ ³ _______
³Power MeterÃÄ´ RF ³ ³ Ex in o´Counter³ ³Osc³ ³CTCSSÃÁ´Selcall³
³ & Range SW³ ³Detector³ ³ ÀÄÄÄÄÂÄÄÙ ÀÄÄÄÙ ÀÄÄÄÄÄÙ ÃÄÄÄÄÄÄÄ´
ÀÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÙ ³ ³ctcss ³Display³
_________ _______ ÀÄÄÄÄÄÄÄÄÄÄ¿ ______³____ ÀÄÄÂÄÄÄÄÙ
³Mod MeterÃÄ´ AF ³ ____________ À´ Automatic ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
³+/-Switch³ ³FiltersÃÄ´Range & ModeÃÄ´Scanning RxÃÄoMod
ÀÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÂÄÄÄÄÄÄÄÂÄÙ
o o
Ext RF In IF Out
It was made in Feltham UK in 1989. It uses PLL oscillators for the RF generator
& CTCSS. Auto RF switching changes the Rx & Counter over & disconnects the
Signal Generator, when the Power Meter detector sees Tx RF, so only the Tx
signal is measured. Useful, but confusing when I was chasing faults!
FAULTS
Going through the maze of functions, I found several faults....
1/ Mains switch. The long push rod had come off the PSU switch, deep inside, &
the button top had swollen & jammed in the front panel. Sanding the button down
& heat glue on the push rod switch end solved this & a rubber sleeve captured
the rod.
2/ Tx Load 40dB attenuator, presented 147ê not 50ê! It looked clean & not
smelling, so not burnt out? I stripped it down, to find it was all quite loose.
It had screw on ends that held large ally washers with spring washers in the
tube surrounding the RF resistors. There were no open circuits Rs or burnt bits
Put backs all together & did up tight, all OK now.
Þ Þ Þ Þ Þ Þ Þ Þ Þ Þ
Small rod type Rs Þ Þ Þ Þ Þ Þ Þ Þ Þ Þ
(o)Ä8êÄÂÄ ÄÄ47êÄÄÄÄÂÄ39êÄ<SMA __Úßßßßßßßßßßßßßßßßßßßß¿
N³ ³ \loose ³ ³ N³ ³Ü._____±_____±_____.³Ä¿SMA
³ 139ê here 14ê ³ ³__³ß'~~~~~±~~~~~±~~~~~'³ÄÙ
ÀÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÙ ÀÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÙ
Disc type Rs Þ Þ Þ Þ Þ Þ Þ Þ Þ Þ
Þ Þ Þ Þ Þ Þ Þ Þ Þ Þ
3/ FM deviation range not right/un-calibratable. Stripping down the Rx unit, I
found a broken 10k preset. Replaced, but needed to be 15K to calibrate the 5kHz
range! Also the 20kHz range need a series preset on the range switch to get
that right too. Inside the Rx box there are also discriminator adjustments that
affect calibration! (previous owner's playing?)
4/ 12V DC input 2 transistor inverter had a NPN collector framing (OK on
isolated battery).
0.25A
LÄÄÄÄo-oÄÄÄÄÄÄÄ/oÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
NÄÄÄÄÄÄÄÄÄÄÄÄÄÄ/oÄÄÄÄÄÄÄÄÄÄÄÄ¿ Mains ³ Transformer
+12VÄo-oÄ´>ÃÄÂÄ/oÄÄÄÄÄÄÄÄÄÄ¿ (((((((((((()
5A ³ ===========³====================
120 ()))) ()))))))))) ()))) ())) ())
³ ³ ³ ³ ³ 8-0-8v ³ Other
INVERTORÃÄÄ(ÄÙ ³ ³ ³ Secondaries
BIAS ³ ³101ÀÄ)ÄÄÄÄÄ¿ ³
³ ÀÄÄÄÄÄ)ÄÄÄ¿ ³ ³
22 \³ ³ ³ ³/
³ ÃÄÙ ÀÄ´
³ e/³ ³\e
0VÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÙ
The cure was to file some metal case away. This may have been from a bad
upgraded from small to large Tab transistors? I also added 4700uF across 12v
input. On off switch stops inverter OK, but leaves bias load on the battery!
Mains lead must not be connected when the 12V is used !!
5/ PM un-calibratable. Something is wrong, had to change op amp gain R in Rx as
a get around. Same as FM for inside the Rx box.
But I did learn that,,, 1 Radian of PM occurs when FM AF Mod Freq = Deviation.
6/ AF Modulation frequencies not very accurate, adjusted one of the Wayne C
values (room for 4 caps on PCB for this), 2 BCD switches operated 8 relays to
controlled the osc Rs. I also put a CR (220 & n82 across the 150R (Thermistor
to earth R) to calibrate the extended upper frequencies after my modification.
(See G/).
7/ CTCSS Pilot tone poor shape @ LF. The output device is ICL 8038BC, so I
added LF frequency correction bias to Set square 1:1 preset, as I have done on
AF osc ICs before, but this correction DC had to come from decoded BCD data
line with Rs added them together this time.
MODIFCATIONS
A/ Made a set of test leads for it.
13A Plug ð===================> IEC right angle Mains
+ >Äfuse¿
- >ÄÄÄÄÄÁ===================> XLR 12V
3.5mm ú-===================ÂÄ> Balanced AF & SINAD
Rig LS ÀÄ> Meters. 4mm plugs
PL259 -é]===================N> N Plug RF Dummy Load in
Both UR67
N Plug <N===================N> N Plug RF Dummy Load in
BNC <========================> BNC general patch lead
B/ I changed the Ovened Reference Oscillator fine tune 10K preset resistor,
inside the counter box for a multi turn version, & drilled a hole to access it
with the inside cover on. This permitted the finest of tweaks when hot without
modifying it for an external off air Reference, that jitters would cause
measuring problems. I also made a polystyrene cover for the hot oscillator box.
This reduces the oven power & makes the temp more stable (& hence Frequency)
more quickly. Warm up time....
Counter error of an air locked 500MHz reference.
Time min 0 1 5 10 15 30 40 50 60
Hz off -30K -1K +261 +122 +95 +69 +50 +42 +31
Error -6/10^5 -2/10^6 5/10^7 3/10^7 2/10^7 <2/10^7 1/10^7 8/10^8 6/10^8
C/ Max deviation measuring range changed from 20kHz to 100kHz. (E.g. now does
5kHz & 100kHz FSD), I put in a 10K series preset on the range switch.
D/ Added Meter illumination LEDs. Ground down 4 white LEDs to a thin square
sliver 4x4x2mm.
__
Original (__³== Ground []== ÚÄÄ´<ÃÄ´<ÃÄ´<ÃÄ´<ÃÄ220Ä<+12V
LED Down LED Á under run white LEDS
Wired up all in series & glued on top of meters, making sure the top fascia
bezel did not foul, & feed them via a 220R from a +12V rail plug nearby Rx.
E/ Added a Rx mode LED (relay's +8V via 470R), so you know which mode it is in.
F/ Stripping out the Selcall from front panel & replacing it with a small LS +
Amp + Vol & a Source switch. So AF in, Notched SINAD AF, Mod, or Rx AF, can be
heard.
+12VÄÄ10ÄÂÄÄÄ¿+
SOURCE ³ ===470u
AF to SINADÄÄÄÄÄÄÄo<ÄÄ¿ ³\³6 Á
u1 ³ 2³ \
SINAD Meter AFÄ´ÃÄo 1M<ÄÄÄÄÄ´LM\ 5 +470u
Log ³386>ÄÄÄÄÄÂÄ´ÃÄ¿
MOD SwitchÄÄÄÄÄÄÄÄo Vol ÚÄÄÄ´ /¿7 10 ³
Pot Á 3³ / ³+ ³ ³_/³8
Rx Mod BNCÄÄÄÄÄÄÄÄo ³ ³/³=== === |_ ³LS
³ 4³ ³10u ³u1 ³ \³
ÁÄÄÄÄÄÄÄÄÄÁÄÁÄÄÄÄÄÁÄÄÄÄÁ
G/ I changed AF mod BCD controlled Wayne Osc's kHz thumbwheel, from Decade to
Hex (from Selcall). This adds 6kHz more range, 100Hz-15.9kHz in 100Hz steps.
But thumbwheel types were not same, so 1 2 4 8 & C lines rewired on ribbon PCB.
See my tech Buls on "
"Analyser Takeda Riken TR4122B", "AF Waveform Generator (RS)", "RTT Mod Meter
(100)", "Marconi Distortion Meter TF2337", "Marconi 2019A Sig Gen"," Systron
Donner 1702 Sig Gen", "198kHz Off Air Standard", "Comparing Off Air Freq
Standards", "Off Air Lock for Ref Osc", & "Scope RF Trick".
Why don't U send an interesting bul?
73 de John, G8MNY @ GB7CIP
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