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G8MNY > TECH 29.10.14 13:58l 170 Lines 8030 Bytes #999 (0) @ WW
BID : 13282_GB7CIP
Read: GUEST
Subj: RTT Comms Test Set
Path: IW8PGT<CX2SA<VE2PKT
Sent: 141029/1157Z @:VE2PKT.#QBC.QC.CAN.NOAM #:59382 :13282_GB7CIP
R:141029/1157Z 2485@N9PMO.#SEWI.WI.USA.NA BPQ1.4.61
R:141029/1156Z 32736@VE3UIL.#EON.ON.CAN.NOAM BPQ1.4.61
R:141029/1155z @:I0OJJ.ILAZ.ITA.EU $:13282_GB7CIP
R:141029/0953Z @:GB7CIP.#32.GBR.EURO #:13282 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Oct 14)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I bought this large test set in it's flight case, made in the UK, 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)
___________________________________________________________
³ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿³
³³ÚÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄ¿ÚÄÄÄÄÄÄÄ¿³³
³³³ \ AF ³³ \SINAD³³ 5 6 0.0 0 0 0 0 0 ³³ \MOD ³³ \POWER³³³
³³³__\____³³__\____³³___________________³³__\____³³__\ ___³³³
AF³³o ³³
in³³o ( )_______( ) (ú) ( ) O ø ! ! ! ( ) O ³³
³³ ³________³ ³³
³³O ( ) o o ( ) ( ) ! ! ( ) ( ) ( ) o ( o ) ³³RF
³³CTCSS SELCAL MOD GEN FREQ . . ³³in
³³1234 123456 12 (ú) 1 2 3 4 5 6 7 (ú) (ú) (ú) (ú)³³
³ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ³
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SO WHAT IS IT?
It is VHF/UHF RF test set with all of these in one Box...
Dummy Load.
Power meter.
Frequency Counter (very accurate).
PLL RF Signal Generator (7 thumbwheels)
PLL CTCSS tone Generator (4 thumbwheels)
Selcall ID Generator & Decoder (No PCB).
AF Oscillator (Wayne type but from 2 thumbwheels!).
AM/FM/PM Modulation Meter (automatic Rx).
SINAD Meter (Sensitivity Testing).
AF Volt & dB meter.
IF Xtal Oscillator.
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 (OK @ 40MHz).
Attenuator 0-9dB +7x 10dB steps gives 1.8uV-50mV before 40dB Load atten.
AF Meter 0.25mV - 10V with dB scale.
Pilot tone(CTCSS) PLL 10Hz-999.9Hz Mod Level adjustable & Counter Decoder.
Selcall PLL 7 char, Mod Level adjustable & Decoder.(No PCB)
Modulation PLL 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, HiFi 50-15KHz.
SCHEMAIIC (reverse engineered)
________ ________ _______________________
AF:ÄÄÄÄÄÄÄÄÄÄÄ´Range SWÃÄ´AF Meter³ MainsÄ´PSU +26,12,10,5,-12,-20³
IN ³ÀÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÙ 12V__/ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
_______ ³ _______ ________ ___________
:ijIF Xtal³ À´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 ³GeneratorÃÄÄÄÄÄ¿ ³ Gen ³
OUT ÀÄÄÄÄÄÄÄÄÄÄÙ ÀÄÂÄÄÄÄÂÄÁÄ¿ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÂÄÄÄÄÄÙ mod³ ÀÄÄÄÄÄÄÙ
RF³ rly³ ³ ³ _______ _³_ ³
___________ _³____³_ ³ ÀÄÄÄÄÄÄÄÄ´ 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_______ call dataÀÄÄÂÄÄÄÄÙ
³Mod MeterÃÄ´ AF ³ ____________ À´ Automatic ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
³+/-Switch³ ³FiltersÃÄ´Range & ModeÃÄ´Scanning RxÃÄoMod
ÀÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÂÄÄÄÄÄÄÄÂÄÙ
o o
Ext RF In IF Out
It was made in UK 1989. It uses several PLL oscillators for the RF generator &
modulation oscillators. Auto RF switching disconnects the Signal Generator when
the Power Meter detector sees Tx RF, so only the Tx signal is measured. Useful
but Confusing when chasing faults!
FAULTS
Going through all mazes of functions it does, I found several faults....
1/ Mains switch. The long push rod had come off the PSU switch deep inside &
also the button top had swollen & jammed in the case. Heat glue & sanding the
button top down solved this.
2/ Load 40dB attenuator. This presented 147ê not 50ê! It looked clean & not
smelling, so not burnt out? So I stripped it down, to find it was all quite
loose, & no open circuits Rs or burnt bits. Put backs all together & did up
tight, all OK now.
Small rod type Rs
(o)Ä8êÄÂÄ ÄÄ47êÄÄÄÄÂÄ39êÄ<SMA
N³ ³ \loose ³ ³
³ 139ê here 14ê ³
ÀÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÙ
Disc type Rs
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. (previous owner's playing?)
4/ 12V DC input inverter NPN collector framing (OK on isolated battery). Filed
metal case away. This may have been from a bad upgraded from small to large Tab
transistors.
5/ PM un-calibratable. Something is wrong I have not found yet, But I did learn
that when FM AF Mod Frequency = Deviation, it gives 1 Radian of Phase Mod.
6/ AF Mod frequency not very accurate, still looking into the 8 relay switched
Wayne Bridge osc. But no outrigger of the strange PCB connector.
MODS
A/ As well as making up a set of test leads for it.
3.5mm ==ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄ>AF & SINAD
Rig LS ÀÄ> Meter
PL259 <0=====================N> N Plug RF Dummy Load in, or BNCs
Both UR67
N Plug <N====================N> N Plug RF Dummy Load in, or BNCs
B/ I changed the 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 Hz in off air locked 500MHz reference.
Time min
0 1 5 10 15 30 40 50 60
-30K -1K +261 +122 +95 +69 50 42 31
6/10^5 2/10^6 5/10^7 3/10^7 2/10^7 <2/10^7 1/10^7 <1/10^7 <1/10^7
C/ Max deviation measuring range changed from 20kHz to 100kHz. (E.g. now does
5kHz & 100kHz), 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. Wired up in series & glued on top of meters, making sure the
top fascia bezel did not foul, & feed them via a 220R from the 12V rail.
E/ Thinking about adding a Tx mode LED, so you know which mode it is in.
F/ I am also thinking of stripping out the Selcall from front panel (no PCB
anyway) & replacing it with a small LS+Amp+Vol & a Source switch. So AF in,
Filtered SINAD AF, Mod, or Rx AF, can be heard.
See my tech Buls on "Syston Donner 115 Pulse 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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