| |
G8MNY > TECH 03.05.16 14:46l 236 Lines 12582 Bytes #999 (0) @ WW
BID : 3121_GB7CIP
Read: GUEST
Subj: Analyser Takeda Riken TR4122B
Path: IW8PGT<IZ3LSV<ED1ZAC<GB7CIP
Sent: 160503/0904Z @:GB7CIP.#32.GBR.EURO #:3121 [Caterham Surrey GBR] $:3121_GB
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Dec 15)
(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 with Digital Store (also badged as Adventest), for a
"song" at a club junk sale. It was not known how well it worked, but I had seen
it switched on at a club's test evening.
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 Out
³ ÀÄÄÄÄÄÄÄÙ . _Ü_ ³
Tracking³(ú) () Ü Ü Ü Ü Ü o . _Ü_ (ú)³RF In
Gen OutÀÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÙ
³ Ü_ O {} {} [}{}{}{} ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
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 (displays to 1750MHz).
Input : 50ê N, +20dBm (100mW) Max, 0-50dB atten in 10dB steps.
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: 50ê BNC with 200MHz @ -30dBm, harmonics checks the sweep cal.
Sweep : 2kHz-100MHz/Div (B/W linkable). Sweep stop for envelope & Phones use.
Phones : AM 3.5mm jack, AM & FM switched 6mm jack on memory unit.
Marker : Movable spot stops sweep momentarily for 8 digit Freq Counter reads.
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, 50ê 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 (unknown Volt/Batt)
Weight : 24kg.
TESTING IT
Well is 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 has a DC isolator to the N socket, so I had to
open it up & unbolt bits to get further.
REPAIR
Located attenuator, to find it was a SMA connected relay controlled remote
module after the N input. On testing I found all the 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, I saw inside 6x 6mm dia tiny uWave relays &
3 RF attenuators & silver track line on the RF substrate. As it was fairly
symmetrical, I was be 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 the attenuator & not the RF input!
Searching Jessop G6JP's RADIO DATA book, I found the theoretical value for the
series arm of a 20dB T atten is 41R. I initially solder tinned the silver strip
lines either side of the faulty R, & tried a small wired resistor of 47R, that
proved OK, so this was the fault!
THE 20dB RELAY ATTENUATOR
2 double change over relays are
1a o-50ÄÂÄ50Äo 2b used 1 & 2 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´ Unused paths terminated.
/ 20R 20R trimR
Fault Á Á Á The fixed trimR used in calibration?
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 venues, it packed up. Fault
was -15V being shorted out & transformer humming. Disconnecting the load wire
brought volts back. The wire went to 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 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.
CRT DISPLAY
Log The Long persistent White/Blue P7
10dB -5 0 +5 Lin 2dB/d Phosphor is viewed through a clear thick
/div 0ÚÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄ¿100% 0 blue glass to give 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 can be switched
100ÀÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÙ0% -20 to LHS or Display centre.
-5 0 +5
CALIBRATION (After 1 hour warm up)
Using the internal 200MHz -30dBm Calibrator, Input Attenuator, Frequency &
Sweep controls, you can check & set front panel CRT Preset Geometry Shifts &
Gains 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.
N.B. Position & Gains interact & repeat adjustments are needed.
Inside are lots more for PSU. Linear & 2dB/Div scales, Filter gain equalisers,
12dB Log pot, Verneer freq pot ends, centre-side offset, as well as RF tweaks
on the S.A. Rx & Gen modules. The RF modules are well sign written, hence I was
able to work out much of a schematic for it...
SCHEMATIC __________
Cal o)ÄÄÄÄÄÄÄÄÄÄÄ´200MHz OscÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
ÀÄÄÄÄÄÂÄÄÄÄÙ ___________ ³ _____
Track _____ ÚÄÄÄÄÄÁÄÄÄÄÄÄÄ¿_³10.7MHz Osc³ ³ ³DC orÃÄDC
Gen o)Ä´AttenÃÄÄÄ´Gen Up Mixers³ ÀÄÄÄÄÄÄÄÄÄÄÄÙ ³ ³MAINS³
Out ÀÄÄÄÄÄÙ ÀÄÂÄÄÄÄÄÄÄÄÄÄÄÙ\ __________ ³ ³ PSU ÃÄ230V
_______ ÚÄÄÄÄÄÁÄ¿ _______ ³411MHz Osc³ ³ ÀÄÄÄÄÄÙ
³ Gated ³ ³YIG UHFÃÄ´ Sweep ³ ÀÄÄÄÄÄÂÄÄÄÄÙ ³
³CounterÃÄ´ Osc ³ ³Control³-------³------------³---------¿AUTO
ÀÄÄÄÂÄÄÄÙ ÀÄÂÄÄÄÄÄÙ ÀÄÂÄÂÄÂÄÙ ³ ³ |
ÚÄÄÄÁÄÄ¿ ³ ³ ³ |speed ³ ³ |
³MarkerÃÄÄÄÄ)ÄÄÄÄÄÄÄÄÄÙ ³ | ³ ³ |
ÀÄÄÄÄÄÄÙ ³ ³ | ³ ³ |
_____ ÚÄÄÁÄ¿ÚÄÄÄÄÄÄÄ¿³ |ÚÄÄÄÄÄ¿ÚÄÁÄÄ¿ÚÄÄÄÄÄ¿ÚÄÁÄÄ¿ÚÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄ¿
In o)´AttenôMix1ôIF GainÃ)Ä)´613IFôMix2ô210IFôMix3ô10.7IF & Filtersÿ
ÀÄÄÄÄÄÙÀÄÄÄÄÙÀÄÄÄÄÄÄÄÙ³ |ÀÄÄÄÄÄÙÀÄÄÄÄÙÀÄÄÄÄÄÙÀÄÄÄÄÙÀÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÙ³
ÚÄÄÄÄÄÄÄ¿ X³ À------<---¿FilterÚ--<------------Ù ³
³ CRT ³ ÚÄÄÄÄÄÄÄÄÄÁÄÄÄ¿ Y ÚÄÄÁÄÄÄÄÄÄÁÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³
³DISPLAYÃÄÂÂÂÄ´DIGITAL STOREÃÄÄÂÄÄ´Video FilterÃÄÄÄ´Lin/Log DetectorÃÄÄ´
ÀÄÄÄÄÄÄÄÙ ³³³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
X o)ÄÄÄÄÄÄÄÄÄÙ³³ & PSU ³ ³
Y o)ÄÄÄÄÄÄÄÄÄÄÙ³ ______ ³ ____________ ³ ³ ³
Z o)ÄÄÄÄÄÄÄÄÄÄÄÙ oÄÄÄÄ´AM AMPÃÄÄÙ ³FM Det & AmpÃÄÄÄÄÄ´
Phones o)ÄÄÄÄÄÄÄÄÄ\o ÀÄÄÄÄÄÄÙ ÀÄÄÂÄÄÄÄÄÄÄÄÄÙ ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
IFo)ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
Understanding the internals does help you use gear better.
The sweeping YIG Oscillator is the heart of this Spectrum Analyser; it uses a
high Q "Yttrium Iron Gamete" bead, like a ferrite core, in the centre of the
UHF coil. It's magnetic inductance is changed with external magnetic field at
right angles to the coil, & 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!
WARM UP DRIFT COMPESNATION
I have found the YIG osc drifts at a different rates at 613MHz than at 2.2GHz.
But this seems too complex to compensate for. I put a 50k NTC thermister
(located & taped to top of the YIG Osc Box below the main vernier Pot, & fed
with dual screened lead). The 100k preset to ground (Cal pot earth) to the
vernier tuning 10 turn pot most +ve lead (~3V).
_ _
0VÄÄ100k_()Ä50kThÄ()_¿
SWEEP PCB __ Preset ³ __ SWEEP PCB
LF cal pot _()Ä¿ ÃÄ()_ HF cal pot
R86 ÀÄÄÄÄÄVerner10KÄÄÄÄÙ R83
/³\ __
ÀÄÄÄÄÄÄÄÄÄ()_ SWEEP PCB Mean Freq
1/ Set FRONT PANEL CAL & FINE TUNE to their mid position.
2/ When warmed up, repeatidly adjust R83 & R86 to give the correct vernier
calibration at 100MHz & at 1400MHz to aggree with centre spot counter.
3/ Check for drift at 1400MHz & adjust Preset for less drift.
4/ Go arould the loop from /2 until drift is reduced
(keep cover on as much as possable to get typical termerature.)
IN USE
Compared to home made & simper commercial Spectrum Analyser I have used, this
"Proper one" 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. But as this is not a modern PLL system, slow drift of the
swept YIG UHF oscillator is quite noticeable on close in work. but it does stop
after 1 hr warm up. One shot sweeps with memory solve 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 near overloading input.
Harmonics & images are well down, if the signals are >5MHz apart so they are
not in the 1st IF together.
The tacking generator is 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 accurcy 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 a measurement. And
Peak store mode lets you capture a rouge signal too.
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". " Spectrum Analyser mods 88-89", "Power Line
Telecomm QRM", "SSB Demo circuit" & "Marconi 2019A Sig Gen"
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
Read previous mail | Read next mail
| |
