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G8MNY > TECH 11.11.25 16:51l 150 Lines 7774 Bytes #5 (0) @ WW
BID : 44801_GB7CIP
Subj: Analyser SWIRES RESEARCH SA87
Path: JH4XSY<N3HYM<GB7YEW<GB7CIP
Sent: 251111/0749Z @:GB7CIP.#32.GBR.EURO #:44801 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Jan 21)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I bought this /P Cable TV spectrum analyser at a rally in 2000. It came with a
nice leather carrying case and charger, but a flat 12V Pb battery. It was made
from 1988 and my one in 1991 in Basildon Essex. The 1st SA in the world to use
a LCD display was their earlier SA85 model!
Brill Freq
ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
ｳ oAux ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ (_) ( ) ｳ
ｳ ()In ｳ ｳ on o (�)ｳCal
ｳ High oDC ｳ L C D ｳ off o sweep oIF ｳ
ｳ ｳ D I S P L A Y S C R E E N ｳband o ( ) ｳ
ｳ oLED ｳ ｳ pk o o ｳ IF
ｳ ()In ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ (_) ｳGain
ｳ Low Y(_) X(_) ｳ
ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
Phones
It came with no information, so a lot or reverse engineering done to make a
full set of diagrams. But I did have a little success with an information
advert sheet from the maker and some history.
FEATURES
Freq : 2 bands 5MHz-450MHz & 450-910MHz (External mixer/osc to 1750MHz)
Input1 : 75ohm BNCs up to 77dBuV (17dBmV) (Actually 20dB Better)
Input2 : 75ohm BNCs 30dB attenuated, to 117dBuV (47dBmV) (Actually 20dB Better)
IF Gain: 10x 3dB steps
IF B/W : 300kHz, added a 30kHz narrow filter option
Cal : 75ohm BNC 50MHz @ 5mV terminated, 74dBuV (14dBmV)
Sweep : Around 4 per sec, gives start & end frequencies
Y : Cursor On floor (my mod) changes Y scale to 5dB/Div
Y : Off floor scale is 3dB/Div & reads out to +/- 0.2dB, 0.1uV
Pk hold: Shows the peak added up over time
X : Cursor line gives frequency readout @ its position
X : Cursor on LHS stops sweep, & draws level line, & H/P can be used
Phones : I added AM Rx opamp driving 3.5mm jack, used when sweep stopped
Display: LCD, added 5 x 10 graticule to estimate the display
AUX : Powers down converter & adjusts Freq display to 1750MHz max
TESTING
Other than an expired small 12V Pb battery it all worked.
INSIDE
Is a double conversion RF module, 10.7MHz IF Module and calibrator, Control PCB
with my piggy backed mods board, Screen Display PCB,LCD, & Controls, DC SMPSU
and battery on the top. All inter-connected with plug in lose wire leads (no
frail ribbons).
ﾚﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄｿ
ｳ ｳ Xtal ｳ ｳ
ｳ ｳ Set Set Freq ｳ ｳ
ｳ ｳ Temp C O N T R O L ｳ ｳ
ｳ ｳ ｳ ｳ
ｳ ｳ Z80 CPU ｳ ｳ Underside
ｳ Set ｳ P C B ｳ ｳ
ｳ Floorｳ Options EPROM ｳ ｳ View
ｳ ｳ SW ｳ ｳ
ｳ IF ｳ ｳ RF ｳ
ｳ ｳ ｳ ｳ Topside has
ｳ UNIT ﾃﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｴ UNIT ｳ SMPSU & battery
ｳ ｳ Controls LCD Screen & Driver PCB ｳ ｳ in the middle
ﾀﾄﾂﾂﾄﾄﾄﾁﾄﾂﾄﾂﾄﾄﾂﾂﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾂﾂﾄﾄﾙ and Set IF Gain.
ﾀﾙ ﾀﾄﾙ ﾀﾙ ﾀﾙ
Cal Input
SCHEMATIC
ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ
Cal o)ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｴ50MHz Oscｳ ﾚﾄﾄﾄﾄｿ
ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ +25Vｴ ﾃﾄCharge DC
Bandwidth>ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ +16Vｵ SM ｳ
Gain>ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ +5Vｴ ﾃﾄ12V Batt
/Tally dB Tally dB/ｳ ｳ -8Vｴ PS ｳ
Low o)ﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ ｳ ﾀﾄﾄﾄﾄﾙ
Inputsﾚﾄﾄﾄﾄﾄｿ ｳ ﾚﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄｿ ﾚﾄﾄﾁﾄﾄｿ ﾚﾄﾄﾁﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾄﾄﾄﾄｿ
Hi o)ｴAttenﾃﾄﾁﾄｴMix1ﾃ>ﾄｴ951MHz IF ﾃﾄｴMix2ﾃ>ﾄｴAttenﾃﾄｴ10.7 IFﾃ>ﾄｴLOG IF ﾃｿ
ﾀﾄﾄﾄﾄﾄﾙ ﾀﾄﾂﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾂﾄﾙ ﾀﾄﾄﾄﾄﾄﾙ ｳFiltersｳ ｳDetectorｳｳ
ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾁﾄｿ ﾚﾄﾄﾄﾄﾄｿﾚﾄﾄﾄﾄﾄｿ ﾚﾄﾁﾄﾄﾄﾄｿ ﾀﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾙｳ
Freq>ﾄﾄﾄｴOsc 951 - ﾃ>ﾄｴ Pre ｳｳ Pre ﾃﾄｴ Osc ｳ ｳ
Band>ﾄﾄﾄｴ1/2 1872MHzｳ ｳScaleｳｳScaleｳ ｳ940MHzｳ ｳ
ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾂﾄﾄﾙﾀﾄﾄﾂﾄﾄﾙ ﾀﾄﾄﾂﾄﾄﾄﾙ ｳ
ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾁﾄｿ ｳ
Brill>ﾄｴ64 x 25chaｳ ｳ Counter PLL ﾃﾄ<Tally dBs ｳ
ｳLCD Screenﾃ<ﾄｴData CONTROL PCB ﾃﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄ<ﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾂﾄﾂﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾙ ｳ
Y >ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ｳ ｳ ﾚﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄｿ ﾚﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄｿ
Cursors ｳ ｳ ｳ8MHz Ref Oscｳ ｳAM H/P Ampｳ
X >ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ｳ ﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾙ
AUX>ﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ ｳ
Phones oﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ
Understanding the internals does help you use gear better!
MODIFICATIONS
1/ Change Pb battery for a 10x 500mA Nicad pack. Adjusted charging shutoff
2/ Added charger plug top status indicators
3/ Added switched narrow 30kHz filter, with sweep width reduction
4/ LCD Brill, range reduced so display not lost
5/ Added another 930MHz IF image trap
6/ Vertical range increased from 18dB to 30dB when Y cursor at bottom
7/ Made graticule for 5/3dB per div indication
8/ Added Sweep stop, with X cursor at LHS
9/ Added H/P amp and 3.5mm socket for AM Rx
10/ Modified Eprom data to remove annoying error message on over scan
11/ Added LCD front panel foil screening to reduce aerial QRM pick up
12/ Made Down converter to see and read to 1750MHz with 900MHz free running osc
IN USE
This /P Spectrum Analyser with no pick up leads, has the advantage it is easily
used to identify QRM sources, to show where they are. With a telescopic aerial
or clip on ferrite pickup one can identify leads that need attention and
actually acurately measure any improvement.
The peak hold can be used to log the occasional QRM source and identify its
level and frequency.
In aerial testing the accurate 0.2dB readout can be used for comparing aerials
measuring gain etc. I use a Scanmaster SP-25 gasfet pre-amp too.
With my VHF pulse tester or a high-level noise source, filters can be tuned up,
like with a tracking generator.
MATCHING
Although the 75ohm impedance may be a nuisance. However a simple 2 resistor
impedance change 5dB attenuator using a 42R in series and 91R across the 50R
port will match correctly (non inductive Rs).
50ohm o)ﾄﾄﾂﾄﾄ42Rﾄﾄ>75ohm 50ohm o)ﾄﾄﾄﾄﾄﾄｿﾚﾄﾄ>75ohm
ｳ 91R ｳ OR ｳ ()))))) ｳ 5x5=25, x2=50ohm
ﾀﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾙ ﾀﾄﾁﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ 1dB?? 6x6=36, x2=72ohm
5dB 5/6t Broadband
ferrite beed
Or use a 5-6 turn ferrite bead auto-transformer.
Further reading;-
Also see my Tech buls on "Plug Top PS charge indicator", "Spectrum Harmonic
Demo circuit", "A Versatile Pulse Tester", "Clip on QRM Probe". "Spectrum
Analyser mods 88-89", "Analyser Takeda Riken TR4122B", "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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