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G8MNY  > TECH     29.06.11 07:56l 116 Lines 6330 Bytes #999 (0) @ WW
BID : 18664_GB7CIP
Read: GUEST
Subj: MEDUSA SIP2300 Generator info
Path: IZ3LSV<IK2XDE<DB0RES<OE6XPE<IW2OHX<UA6ADV<GB7CIP
Sent: 110628/2316Z @:GB7CIP.#32.GBR.EU #:18664 [Caterham] $:18664_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To  : TECH@WW

By G8MNY                                       (Updated Jun 11)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

I bought a MEDUSA SIP2300 4 stroke petrol generators as the were so cheap (just
in case we have power cuts!). It is the same generator as the WOLF 2.3kW.

It is fairly quiet @ 73dBA @ 4m. The large 12 l tank gives approx 10 hours run
time. It is not too heavy @ 83kg full, 41kg dry, to move it by oneself (only on
& off a low level trolley & lift into van etc!)

                                        Gauge   Filler
 ÜÜßßßßßßßßßßßßßßßÜÜ                Û  _.==ÄÄÄÄÄðððððÄÄÄÄÄÄ.._  Û Tube
Û/~~~~~~Tank~~~~~~~\Û               Û/"     Large 12L Tank    "\Û Cage
Û-------------------Û      Fuel Tap Û===========================Û
Û\_____________/~~~~Û      & filter\Û|"""""~~~~~~~~~~~~~~~"""""|Û
Û    Tap(0)   ³elec Û           STOPÛÞ [] øOK ³ on³  " AC "    ÝÛ  AC
ÛChoke //   Sol\____Û         SWITCHÛ |_  øOil³ º ³ = =  = = _| Û 2x13A
ÛÚÄÄÄÄ¿  /~~~~~\\.  ÛPull           Û³~~""---..........---""~~³³Û
Û³In- ³,' /~~~\//\\ ÛStart          Û³F ³ENGINE      |     |  ³³Û
Û³Take³³ ³ ( ) ³  ³ Û               Û³A ³       (=)oil ALT |  ³³Û
ÛÀÄÄÄÄÙ \ \___/  /  Û               Û³N ³  _____³_³__|_____|  ³³Û
Û     Ú' ÚÄÄÄÄÄ¿ `¿ Û               ÛÀÄÄÁÄÄÜÙ           ÀÜÁÄÄÄÁÙÛ
ß"""""""""""""""""""ß                ßßßßßßßßßßßßßßßßßßßßßßßßßßß

I have modified it for /P contesting, to power several 400W valve PAs for as
per my bul on "Petrol Gennys for /P SSB". With my rev up modification (add a
solenoid for FEED FORWARD load compensation) the measured performance is now...

Generator      Unmodified                   Modified
 Load kW        Volts  Hz               Volts  Hz  Uplift %
   0             250   55                250   55    0
  0.1            235   54                238   55    0.3
  1.0            225   53                234   55    4
  2.0 Rated      215   51                235   55    6.4
  2.3 Old Peak   200   49                233   55   16.5
  2.5            190   47                235   55   23.7
  3.0 New peak   180   45 33% throttle   220   54   22.2  @ FULL THROTTLE!

It is not intended that continuous loads over 2kW be used, just speech peaks
etc. to go to 3kW peak load. Before the modification it was not possible to
activate the 10A thermal output trip on good power factor loads, after this
modification it is now possible!

At 50Hz you only get 225V output, but it is more economical to use lower RPM if
the peak power is not needed! There is no 2 speed option for this generator,
but a long screwdriver will adjust the voltage/RPM spring OK. Note the off load
voltage is quite a bit higher than even with a 100W lamp.

Other Mods I did were..
1/ Added earth bonding from engine, to frame, & to electric panel plate.
2/ Added earth lead & earth clip for external earth stake.
3/ Added engine ignition lead screening, & made a screen tube for the plug cap.
4/ Painted Alternator casing black to improve heat dissipation.

CIRCUIT
I have reverse engineered the diagram...
                                                                    STOP
 ÚÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂo/oÂÄÄÂÄÄ¿
 ³gn/ye       ³  2x13A  ÃÄÄÄÄÄ¿front      External Earth         ³   ³  ³  ³
 ³            E   AC    E    _³_panel                            ³   ³  ³  ³
 ³      bk  N   L     N   L  ///                                 ³   ³  ³  ³
 ³       ÚÄÄ´   ÃÄÄÄÄÄ)ÄÄÄÙ      Ú - - - - - - - - - - - - - - ¿ ³   ³  ³  ³
 ³       ³  ÀÄÄÄ)ÄÄÄÄÄ´          |  ÚÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´<ÃÄÄÄÄÙ   ³  ³  ³
 ³      Run     ³     ³          | _³_D2³                ³ D1  |     ³  ³  ³
 ³      Neon   10A    ³          | /_\ _³_              _³_    |  bk/³  ³  ³
 ³       ³    Trip    ³bk        |  ³  \_/Q2          Q1\_/    |   wh³  ³  ³
 ³       ÀÄÄÄÄÄÄ´     ³          |  ³   ³\     ÚZD  ____/³     |     ³  ³  ³
 ³              ³rd   ³  Added   |  ³   ³ Ã47êÄ´<ÃÄ´     ÃÄÄÄÄÄÄÄÄÄÄÄÙ  ³  ³
 ³  25u 450V    ³     ³Solenoid  |  ³   ³ ³        ÀÄ200ê´     |       Oil ³
 ³  ÚÄ´ÃÄ¿(155V)³     ³-------¿  | 50ê  ³ ÀÄÂÄÄÂÄÄÂÄÄÄ¿ +³C1   |      Neon ³
 ³  ³    ³      ³     ³ ===== ³  |  ³   ³  _³_ 1k ³C2 ³ ===47u |        ³  ³
 ³  ³    ³      ³     ³_(((()_³  |  ³   ³D3/_\ ³ === 2k  ³63v  | ye     ³  ³
 ³  ³ye  ³ye    ³     ³  0.2ê    |  ÀÄÄÄÁÄÄÄÁÄÄÁÄÄÁÄÄÄ)ÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ  ³
 ³  ³    ³      ³     ³          |        P C B       ³        |           ³
 ³_ ³_ _ ³_ _ _ ³ _ _ ³ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ ³ _ _ _ _| _ _ _ _ _ ³
 ³  ³or  ³or    ³rd   ³bk  |          __  oil       bk³              bk/wh ³
 ³  ³1.4ê³      ³1.8ê ³    | Timing |(  ÃÄo/oÄÂÄÄÄÄÄÄÄÙ         Ú5kÄÄÄÄ¿   ³
_³_ À((()Ù ==== À(((()Ù    | Pickup |(  ÀÄ´ÃÄÄÙ               Spark  ||(6k ³
///  ==== Ú(((()¿ ====     |  -2V   _³_  1n ?                 Plug   ||(___³
          ÀÄ´>ÃÄÙ          |        ///                              ||( 1ê
     A L T E R N A T O R   |   C R A N K C A S E        M A G N E T O _³_
                           |                ÚÄÄÄÄÄÄÄÄÄ¿               ///
                                       TUBE_³_ gn/ye _³_ FAN
                                      FRAME///       /// COWLING
EXCITATION
This is a brushless excitation with the rotor magnetically charged up each half
cycle from circulating 90deg out of phase currents from the exciting capacitor.
In the rotor is 4x 3A 200V diodes in series parallel (a small back EMF R)
across the winding to maintain the current half a cycle after the kick. This
system is more reliable than brushes but does produce a kink in the load
winding waveform.

ELECTRONIC IGNITION
The electronic ignition works in a strange way, as top dead centre approaches a
voltage of -80V or so is made by the magneto primary, this is shorted out when
the timing pulse triggers the SCR, shorting this voltage & producing an
ignition voltage in the magneto secondary.

Only one wire from the crankcase handles both the timing & the oil status. If
low oil, the crankcase oil switch is not made, & the ignition is killed after
the oil warning neon light is lit for 30 seconds.

Does anyone really understand the operation of this ignition circuit?


See my TECH buls "MEDUSA SIP2300 Generator Repairs" & "Petrol Generators for
/P SSB".


Y Don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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