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G8MNY > TECH 25.04.24 03:02z 324 Lines 17399 Bytes #30 (0) @ WW
BID : 5566_GB7CIP
Subj: Analyser Takeda Riken TR4122B
Path: SR8BBS<SR4BBX<DB0RES<DB0ERF<DK0WUE<PD0LPM<I0OJJ<GB7CIP
Sent: 240416/0659Z @:GB7CIP.#32.GBR.EURO #:5566 [Caterham Surrey GBR] $:5566_GB
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Mar 24)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Being a sucker for test gear, I bought this rather large & very heavy vintage
Japanese Spectrum Analyser, also badged as Adventest, for a "song" at a club
junk sale. It has a tracking generator & 2 digital stores. It was not known how
well it worked, but I had seen it switched on at a club's test evening, so I
knew it was not quite all OK.
Vernier Readout
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿Freq Tune
³oÚÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³~~~~~~³( O )³
CRT ³o³ ³ øÀÄÄÄÄÄÄÙ ³LHS/Center
Controls³o³ ³ . Ü_ ß- ³
³.³ DISPLAY ³ úSweep ³Scan &
³.³ ³ ( O ) ( O ) ³Bandwidth
On/Off³O³ ³ & Spot Ü_³
³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÙ Atten ³Vid Filter
³. . . ÚÄÄÄÄÄÄÄ¿ & Gain ³
Presets³. . . ³Counter³ ( O ) (0) 0³Cal BNC
³ ÀÄÄÄÄÄÄÄÙ . _Ü_ ³
Tracking³(ú) () Ü Ü Ü Ü Ü o . _Ü_ (ú)³N RF In
Gen OutÀÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÙ
³ Ü_ O [] [] [][][][] ³
ÀÂÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÂÙ
Phones Digital store unit
It came with no information or front cover, but here is my spec for it so far..
FEATURES
Freq : 100kHz-1500MHz (Display & Mechanical Vernier counter to 1750MHz)
Input : 50ohm N,+20dBm(0.1W)Max, 0-50dB atten, in 10dB steps, 1dB comp @-10dBm
IF Gain: 0 to +50dB, in 10dB steps (Gain/loss scale) & a Calibrated +12dB Pot
IF B/W : 3MHz, 1MHz, 100kHz, 10kHz, 1kHz, & 500Hz, all sweep friendly shape
Video : Video filter, 1/30 of IF BW. For noise averaging, sweep speed adjusts
Cal out: 50R BNC with 200MHz @ -30dBm, harmonics check to 1400MHz sweep cal.
Sweep : 2kHz-100MHz/Div (B/W linkable). Sweep stop for envelope & Phones use
Phones : AM 3.5mm jack, and AM/FM switched 6mm jack on memory unit
Marker : Movable spot stops sweep momentarily, for 8 digit Freq Counter readout
Modes : Trace (U sweep marker spot) / Manual select sweep time / Auto (best)
Display: Linear / 2dB/Div / 10dB/Div. 10 x 10 Div etched tube graticule
Gen out: Tracking Generator, optional filters. 0 to -50dBm in 10dBs, 50R N
Store : 2 Digital memories, one can be subtracted to normalise display
Outputs: IF @ 10.7MHz, X, Y, & Z, for a 2nd display. Data/printer socket out
Power : 122VA selectable AC Volts internal / External DC (Special Batt pack)
Weight : 24kg!
TESTING IT
Well it was very cheap, so I expected the odd problem, I soon saw one. The
precision input attenuator was broken. The first 10 20 & 30dB worked, but 40 &
50dB fell off the screen. It had a DC isolator to the input N socket, so I had
to open it up & unbolt bits to test further.
1st REPAIR
I located the attenuator, to find it was a SMA connected relay controlled
remote module after the N input. On testing I found all the relay control lines
went on & off OK, so it was not a control switch or relay drive logic fault.
Removed attenuator, took off the RF cover. Inside I saw 6x 6mm dia tiny uWave
relays & 3 RF attenuators & silver track line on the RF low loss substrate. It
was fairly symmetrical, & I was able to identify an open circuit metal
deposited R only 2mm square, on the input side of the offending 20dB attenuator
section. So it had been "burnt out", luckily only this attenuator & not the RF
input!
Searching Jessop G6JP's RADIO DATA book, I found the theoretical value for the
series arms of a 50R 20dB T atten should be 41R. I initially solder tinned the
silver strip lines either side of the faulty R, & tried a small lead resistor
of 47R, that proved OK, so this realy was the fault!
THE 1st 20dB RELAY ATTENUATOR
2 double pole change over relays 1
1a o-50RÂ50RÄo 2b & 2 are used, this ensures high
o___ 1b Á 2a ___o isolation with 4 contacts bypassing
SMA o)_/ \o_________o/ \__Next the through path when attenuating.
Input Á o o Atten
50ê ÀÄÄ41RÄÄÄÂÄÂÄÄÄ41RÄÄ´ The unused paths are terminated.
/ 20R 20R trimR
Fault Á Á Á The fixed trimR used in calibration?
So for a proper job, the 41R had to be accurate, small & non inductive, if it
was to work well to 1500MHz. After consulting an old Basic Hamhelp Program for
multiple Rs, I used 3 surface mount Rs in parallel 2x100R & a 220R to give the
41R. Once stacked up & soldering together the SM Rs were not too difficult to
solder to the pre-tinned stripline, although it looked a bit messy in the end.
Success, re-assemble & tested, display now showed nice even steps of the 40 &
50dB atten & all exactly 10.0dB & quite flat to 1.5GHz.
2nd REPAIR
Later after many days of use & taking it to club fixit nights, it packed up!
The fault was a humming transformer & I found -15V was being shorted out!
Disconnecting the PSU load wire brought the volts back. The wire went to the
motherboard, so I pulled out the 5 cards & short went on my meter. The Log
detector PCB had the short, no high power components, just 10 x 10dB gain amps/
detectors. With the -rail the track was easily identified with its electrolytic
caps +ve to earth. I removed 3 of them, but they were not faulty, eventually I
came to the end of the double sided weaving track, to see a mechanical 3mm long
soldered lead bent over & shorting to adjacent earth. Fixed OK.
3rd REPAIR
After a lot of soak testing, to null some of the frequency drift, I noticed
ripples appearing on the digital store trace line. This was hum was on the +5V
in the difficult to access add on lower memory unit. The reservoir cap value
before the regulator, was low for the current at only 1000uF, & the +15V PSU
had 2 of them, so I swapped 1 of them over to the 5V PSU, & halved the pre reg
ripple, so all OK. On closer examination of the piggyback 2nd memory PCB, I
noted 2 Tant caps on the 5V rail had changed colour. Testing them 1 was as low
1K. It seems that this added load to the mis wired PSU C gave the fault. After
replacing them, & destroying 2 more, I DC tested to realised the silk screen
legend was actually wrong, with + on the -ve lead! So an original maker's PCB
fault I was not expecting!
CRT DISPLAY
Log The Long persistent White/Blue P7
10dB -5 0 +5 Lin 2dB Phosphor is viewed through a clear
/div 0ÚÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄ¿100% 0 /div thick blue glass gives a clear display.
10ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´90%
20ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´80% Usual Brill, Focus, & a bottom blanking
30ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´70% controls, Astig & Geom are presets.
40ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´60%
50ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´50% -10 10 x 10 div graticule with 0.2div
60ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´40% marks, are etched inside the tube
70ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´30% for accurate no parallax readings.
80ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´20%
90ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´10% The Tune Freq calibration can be
100ÀÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÙ0% -20 switched to LHS or Display centre.
-5 0 +5
ONCE WARMED UP:-
X: With centre freq mode, Zooming in with sweep range & on a signal (Zero Line)
in the middle & then zooming out, sets the X screen position middle.
Frequency cal lines (& harmonics) set the X Gain to get scale right.
Y: Linear scale mode, no signal defines the lower Y graticule. Y Gain is set in
10dB/Div mode, over 90dB of atten/IF gain, to get the scale right.
Memory: Repeat for the 4 preset Shift & Gains on the side of the memory unit,
so there is no difference with memory on/off. N.B. Position & Gains interact &
repeat adjustments may be needed.
INSIDE
The underside has the RF modules, which are well sign written, hence I was able
to work out much of a schematic for it..
SCHEMATIC __________
Cal o)ÄÄÄÄ<ÄÄÄÄÄÄ´200MHz OscÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
ÀÄÄÄÄÄÂÄÄÄÄÙ ___________ ³ _____
Track _____ ÚÄÄÄÄÄÁÄÄÄÄÄÄÄ¿__³10.7MHz Osc³ ³ ñ15VµDC orÃÄDC
Gen o)´AttenÃÂÄ>Ä´Gen Up Mixers³_ ÀÄÄÄÄÄÄÄÄÄÄÄÙ ³ +5V´MAINS³
Out ÀÄÄÄÄÄÙ³ ÀÄÂÄÄÄÄÄÄÄÄÄÄÄÙ ³ __________ ³ +150V´ PSU ÃÄ230V
_______ ³ÚÄÄÄÄÁÄÄ¿ _______ À´411MHz Osc³ ³ ÀÄÄÄÄÄÙ
³ Gated ³ ³³YIG UHFÃÄ´ Sweep ³ ÀÄÄÄÄÄÄÂÄÄÄÙ ³
³CounterÃÄÙ³ Osc ³ ³Control³--------³------------³---------¿AUTO
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ÚÄÄÄÁÄÄ¿ ³ Frequency ³ ³ |speed ³ ³ |
³MarkerÃÄÄÄÄ)ÄÄÄÄÄÄÄÄÄ<ÄÙ ³ | ³ ³ |
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In o)´AttenôMix1ôIF GainÃ>Ä)Ä)´613IFôMix2ô210IFôMix3ô10.7IF & Filtersÿ
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³ CRT ³ ÚÄÄÄÄÄÄÄÄÄÁÄ¿ Y ÚÄÄÁÄÄÄÄÄÄÁÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³
³DISPLAYÃÄÂÂÂÄÄÄ´ DIGITAL ÃÄÄÂÄÄ<Ä´Video FilterÃÄ<Ä´Lin/Log DetectorÃÄ<´
ÀÄÄÄÄÄÄÄÙ ³³³ ³STORE & PSU³ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
X o)ÄÄÄÄÄÄÄÄÄÙ³³ ÀÄÄÄÄÄÄÄÄÄÄÄÙ ³ ³
Y o)ÄÄÄÄÄÄÄÄÄÄÙ³ ______ ³ ____________ ³
Z o)ÄÄÄÄÄÄÄÄÄÄÄÙ oÄÄÄÄ´AM AMPÃÄÄÙ ³FM Det & AmpÃÄÄÄÄ<´
Phones o)ÄÄÄÄÄÄÄÄÄ\o ÀÄÄÄÄÄÄÙ ÀÄÄÂÄÄÄÄÄÄÄÄÄÙ ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
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Understanding the internals does help you use gear better.
YIG UHF OSCILLATOR
This is the heart of this Spectrum Analyser; it uses a free running UHF osc,
with a temperature controlled high Q "Yttrium Iron Gamete" bead, like a ferrite
core, in the centre of the UHF osc coil. It's magnetic inductance is changed
with powerful external magnetic field at right angles to the UHF coil, & this
linearly sweeps the oscillator between 613-2113MHz. YIGs are very stable (when
temperature controlled) & like Xtal oscillators have very low noise sidebands,
unlike PLL & DDS sources, have NO sprogies/spurs, but with no PLL they drift!
WARM UP DRIFT COMPESNATION
On close in work I have found the YIG osc drifts a good 30MHz @ 1400MHz from
cold to hot. To try to compensate this, I used a 47K NTC thermistor with an
insulated in heat shrink & polystyrene cover, all taped to top of the warming
YIG Osc Box mounting point, 10cm below the main geared vernier Pot, & fed with
a screened lead to reduce any hum pickup.
Earthed @ Preset1
SWEEP CAL 0VÄÄ100KÄÄÄÄ47KThÄÄÄ¿
À - - - - - - - ¿³ ~+5V DC from
SWEEP PCB __ ³ __ SWEEP PCB
LF cal _()ÄÄÄÄÄÄVerner10KÄÄÄÄÁÄÄ()_ HF cal
pot R86 /³\ pot R83 Comparitor
³ __ FET
ÀÄÄÄÄÄÄÄÄÄÄÄ()_ SWEEP PCB Mean FreqÄ10KÄÂÄÄGate
===1uF
Á
One end of the thermistor goes to ground (Cal pot earth point) via Preset 1.
This limits the temperature compensation action at hottest temp. The other end
is wired to the 10 turn vernier tuning pot (most +ve lead ~5V) which is the DC
feed from pot R83, & which also sets the slope (gain) of the compensation
action feed from pot R83.
Minimising drift..
1/ Set FRONT PANEL "CAL" & "FINE TUNE" controls to mid position.
2/ When warmed for only 5 mins, repeatedly adjust R86 & R83 to give the correct
vernier calibration @ 200MHz R66 & R83 on the 7th harmonic at 1400MHz of the
200MHz Cal Ref. to agree with centre marker spot counter frequency.
3/ When warmed up with cover on for 1hr, set vernier to 1400 & adjust Preset1
for 1400MHz on the counter. Note there is some temperature / magnetic /
hysterisis settling time on the YIG osc until it & the control circuit
settle down & stop drifting.
4/ Let it cool down for an hour or so (cover off?), & go around the loop from
2/ again & again, until hot & cold frequencies do not need adjusting
(eg. within +/-3MHz @ 1400MHz).
N.B. This will not stop all display drift when zoomed right in & @ 500Hz B/W,
but it will make a big difference!
CALIBRATION (After warm up)
Using the internal 200MHz -30dBm Calibrator & its harmonics, with a patch lead
you can do most of the calibration:- Test Input Attenuators, IF preset gains,
Frequency & Sweep controls, & you can check & set front panel CRT Preset
Geometry, Shifts, & Gains, etc. Under the top cover are lots of presets &
timers for..
PSU, has 5 pots for setting left to right +15, -15, +5, & +150V.
EHT Box, next to the CRT has 2 presets for "EHT" & "Focus" etc.
Sweep board PCB, is next to the CRT & at back "Pincushion", & "Trapezium"
geometry pots, then "unknown pot", then "Y shift", "2dB mode gain", & "2dB mode
base line" pots.
The Log Amp Screened PCB adjacent, has no accessible adjustment presets.
IF PCB, has gain equalising pots between filter bandwidths "100kHz", a "shape
trimmer", "under 100kHz". Then pots for the "+30dB", +20dB", "+10dB" control, &
gain control "+12dB", "0dB gain control" cal pots, then an overall gain preset
pot used with front panel Cal @ centre.
IF Filter screened PCB, has 1 preset for gain equalising "wider than 100kHz".
Timebase PCB, has 3 interacting sweep speed pots that control the complex sweep
stop & measure spot frequency & carry on. Scope test point & adjust time with
spot off screen for best time accuracy in manual time mode. Nearest pot is
another for "trigger", used in mains Line lock & Video modes.
Sweep PCB, has control of YIG osc magnetic field current & freq limits. Middle
of PCB is "X gain", an "unknown", "R83 1400MHz", "R86 200MHz".
On the underside there are several metal boxes..
The RF unit has 200MHz Calibrator "RF Level" pot, & "Freq" trimmer. With a
patch cable in, the 613 & 230MHz IFs can all be carefully peaked. Several of
the RF unit controls feed ref osc to the tracking generator box, & are adjusted
with a Generator patch cable in place. Use wide sweep to see a flattest line to
1500MHz.
The tracking generator box, has harmonic filters in filter mode, & a rippled
line is displayed. Adjust all, for best flattest line. Adjust O/P match
flattest near 1500MHz & Output level for correct level.
The Counter can be calibrated with an external ref osc @ 100MHz patched in
after the 1/10 pre-scalar box, to read 1000MHz.
Underneath & difficult to access, is the add on memory unit. It has presets for
"Y top" gain clip, "Playback sharpness" trimmer, "Y in" Bottom clip, (test on
2dB range), "X position" trigger, "X in" gain. On the 2nd memory Piggy back
card is a "spot" location pot to set it identical to the non memory position.
IN USE
Compared to simple home made & commercial Spectrum Analyser I have used, this
"Proper one" is not as sensitive & takes some getting use to. With the multiple
bandwidths available from 3MHz for fast sweeps right down to 500Hz close in
work. The inter-lockable Sweep & Bandwidth control & the Auto sweep speed,
stops you getting a faulty spectrum display (warning LED). But as this is not a
modern PLL system, slow drift of the swept YIG UHF oscillator is noticeable on
close in work. but it does reduce after 1 hr warm up or so. One shot sweeps
with memory easily solves most of this drawback though.
The Zero Hz line can be seen when the YIG Osc is on the 1st IF freq, as well as
about 300MHz of the spectrum mirror image.
With slow sweep, narrow bandwidth, video filter in & the storage memory, the
noise floor can be seen as low as 98dB down on a just overloading 0dBm input.
Harmonics & images are well down, if the signals are >3MHz apart so they are
not in the 1st IF together.
The tacking generator with sweep stopped can be used as an RF generator, it is
also very useful on filters & pre-amps etc. But the first thing you notice is
all your bad cables & connectors! Of course it can also be used just a sweep
gen too, triggering a scope from Z out etc.
Best accuracy for adjustments is in Linear mode or the expanded 2dB/Div.
The 2 memories can be used in subtraction mode, so a change in display can be
seen, or an un-flat response of test leads normalised before measurement. And
the Peak store mode lets you capture a rouge signal too.
For power RF inputs, I have a N connected 50W 40dB attenuator DC-5GHz to put in
front, so hopefully I will not be burning out the input!
FURTHER INFORMATION
I have only found 3 pages of the user manual on line so far, without buying the
full price set of 5 manuals, so I wonder if any readers have used this S.A. or
have any information on it?
Also see my Tech buls on "Spectrum Harmonic Demo circuit", "A Versatile Pulse
Tester", "Clip on QRM Probe". "Analyser SWIRES RESEARCH SA87", "Spectrum
Analyser mods 88-89", "Power Line Telecomm QRM", "SSB Demo circuit", "Marconi
2019A Sig Gen", "FeelTeck Dual DDS Osc FY6600-60M", & "RF Directional Coupler".
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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