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G8MNY > TECH 10.11.15 12:01l 99 Lines 4821 Bytes #999 (0) @ WW
BID : 47810_GB7CIP
Read: GUEST
Subj: Marconi 2019A Sig Gen
Path: IW8PGT<IZ3LSV<IK6ZDE<I0OJJ<IR0AAB<GB7CIP
Sent: 151110/0955Z @:GB7CIP.#32.GBR.EURO #:47810 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Nov 15)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I acquired this old large 19" 3U rack unit, a digital entry controlled signal
generator.
Frequency Modulation Level
___________________________________________________________
³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³
³ ³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄ¿ ³ ³
³ ³ ³ 1040.0000 MHz ³ ³ 75.0 kHz ³ ³ -127 dBm ³ ³ ³
³ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÙ ³ ³
Mod Fr³ ³[]::: [] [][] [][][] [] [][] [] ³ ³
Ex ALC³ ³[] step [][] [][][] [] [][] fun2 (ú) ³ ³ AF out
³ ³ [][] [][][] [] [][] ³ ³
On/Off³ ³ o (ú).(ú) [][] [][][] [] [][] ( o ) ³ ³ RF out
³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
~~~~~ÜÜÜÜ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ÜÜÜÜ~~~~~
Ex mod Parm Data Unit Disable
FAULTS
It was falling apart, but a few screws sorted that, but I had to make missing
side cheeks strips. It seems to work OK, & I was able to fully test it. AF Osc
frequencies were all a bit LF, so I changed the 2 Wayne bridge Osc's 10nF for
9,75nF as I had some, spot on now. I found the FM calibration using 1st Bessel
null @ 2.40kHz Dev & 1kHz was out of cal range so I added a tweak R, feeding
the preset, but exact calibration was variable. With aid of a down loaded .pdf
service manual, this 1st proved to be AB2 PCB relays & ops amp for FM mod high
level AF attenuators, but later to a R1 50R link through in the Osc Board. (Mod
board has software controlled digital attenuators). Re soldered PCB AF paths
seems OK now, but accurate FM calibration is still a bit temperature conscious.
SPECIFICATION
Frequency : Range 80kHz (OK down to 30kHz) to 1040.0000MHz in 100Hz steps.
PLL Frequency is 7.5 digit readout.
Mod AF : 300, 400, 500, 1k, 3k, & 6k Hz 5%, for AM FM PM & AF out.
Ext Mod : BNC, 0-100kHz, Cal Level warning LEDs/ALC for level calibration.
Ext FM Mod: 2nd Mod input allows pilot tones etc. to be added.
Mod Level : AM 0-99%, FM 0-1MHz (VHF) Dev, PM (0M) 0-999 Radian. 3 dig readout.
AF Output : BNC. 100uV to 5V RMS. -77.8 to +16.2dBm max. 3.5 dig readout.
RF Output : N 50ê. 0.1uV to 2V RMS, -127 to +13dBm max.
Memories : Store & recall of 100 memories 0-20 full params, non volatile.
Keys : Orange start data entry, Black Data, Grey Unit end. Blue 2nd mode.
Accuracy : < 1/10^7 after 5min. Temperature controlled Xtal oven reference.
In out Ref: Rear 10MHz (1MHz Programmable) BNC for ref Out/In.
Spurious : Harmonics -30dBc typically -60dBc, & spuri lower than -65dBc.
Protection: Accidental Tx RF OK to 50W Max!
Power : 55W 230V Adjustable. IEC socket RT angle plug to stand up on end.
Weight : 17kg.
CALIBRATION
On RHS cover there is a hole for the Ref Osc tweak (thin screwdriver). Inside
the top cover there are PSU for voltages 24 15 5 & -15V. Behind the front there
plug in Modulation PCB & its row of presets for Ext Gain, Ext ALC, Ext non ALC
Threshold (hi/low leds), PM, AM, & FM.
Marconi software map AF Gain changes for the 4 FM oscillators at 82 frequencies
points, to keep calibration. Simular maped changes for AM, Phase, & RF Level.
OPERATION
Power up gives software version 003 for a sec, then default setting 1040MHz
@ -127dBm, 0 mod. (Memory 10 can be used power up parms see user manual)
1/ Press orange Freq key, enter freq, & end with a grey MHz/kHz/Hz key.
2/ Press orange RF Level key, enter level, & end with a grey dBm/V/mV/uV key.
3/ Press orange AM/FM/PM if needed, enter mod level & its grey unit key.
4/ Select a black Disable key, eg. RF/AF/Mod off/on etc. as needed.
/_\ Delta, shows unit steps for the ^v keys. & allows changes.
2nd Function key, for additional set-ups see handbook. Orange key reset.
External key, gives error code ---15--- if no Ext Ref. Orange key reset.
USES
Although far more complex to use than my older Systron Donner Sig gen, it is
lighter, & lends itself for FM & AM demos on Ham training courses, etc. Rx
alignment & sensitivity tests, as it has a well screened RF output with 140dB
range. Also its wide FM modulation of 1MHz deviation (>100MHz) with up to
100kHz of External AF, is useful for accurate calibration of broadcast
deviation meters & compensating their frequency response.
See my tech Buls on "Syston Donner Sig Gen", "Analyser Takeda Riken TR4122B"
"RTT Comms Test Set", "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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