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G8MNY > TECH 24.08.13 09:59l 84 Lines 3459 Bytes #999 (0) @ WW
BID : 34470_GB7CIP
Read: GUEST
Subj: Inverter Petrol Generators
Path: IZ3LSV<IW0QNL<JH4XSY<JE7YGF<7M3TJZ<UA6ADV<GB7CIP
Sent: 130824/0708Z @:GB7CIP.#32.GBR.EU #:34470 [Caterham Surrey GBR] $:34470_GB
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (New Aug 13)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
At a recent summer camp we tested out a new 2.2kW generator...
______
.==ú'(__) ³ Modern electronic inverter type
/ ³ generators (Honda/Clark) produce
Þ [][] : ø ø ³ excellent stable power output, with
³ ³ good sine wave under heavy changing
³ø ³ rectified mains loads. (e.g. 400W SSB Tx)
ÀÂÂÄÄÄÄÄÄÄÄÂÂÙ
Unlike conventional generators that run at a constant 3000 RPM, the inverter
type can tick over quietly at low revs & save a lot of energy (fuel) under
light loads, & rev up to well over 3000RPM (e.g. 500-5000 RPM). The higher revs
means a smaller CC & lighter engine can be used. But it is quite noisy at full
load!
ÚÄÄÄÄÄÄÄÄÄÄÄÄ¿ 350V DC ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄ¿
³HIGH VOLTAGEÃÄÄÄÂÄÄÄÄÄÄÂÄÄ´L & N HF PULSEÃÄ´GENNY MAINSÃÄÄ>230V
³ ALTERNATOR ³ ³ C === ³ WIDTH SINE ³ ³ FILTER ³ 50Hz
ÀÄÄÄÄÄÄÄÄÄÄÄÄÙ \³/ ³ ³ WAVE INVETER ³ ÀÄÄÄÄÄÂÄÄÄÄÄÙ SINEWAVE
Engine ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ _³_
Speed Feedback 10kHz-50MHz ///
The engine throttle feedback is used to maintain the high voltage DC. A large C
ensures there is enough DC stored to meet the sudden demands until the engine
revs up.
HF NOISE
You don't get something for nothing. The genny mains filter used to clean up
the output is quite good, but not for sensitive ham HF work! The inverter
produces broadband noise with a slight buzzy hum content.
EXTRA MAINS FILTERING
Tests were done at a quiet /P site with Rx preamp on. The interference mode to
the Rx was found to be "common mode" via the mains to PSU & PA etc, & not
radiated to the nearby aerials. (to the limit of band noise floor)
Testing with various mains filters showed on the S meter something like this..
Generator None Normal -------------- Inverter Type Genny with --------------
On 4 stroke No Plug Plug Large Both Earth Filter with
Band Batt Genny Filter Top Top x2 Filter Filters Only Earth Choke
20m S1 S1 S7 S4 S3 S3 S2 S6 S2
40m S2 S2 S9 S5 S4 S5 S4 S8 S3
80m S3 S3 S9+ S5 S4 S6 S4 S9 S4
GOLD
STANDARD
The "Normal Genny" had fully suppressed ignition. The "Plug Top" filter was old
BT type, & the "Large Filter" was a huge "brick" sized standard motor type. As
they performed slightly differently, they were also tested together "Both" for
a slight improvement over either one.
The tests with "just the earth wire" connected, proved there was quite a bit of
conducted RFI on it & a mains filter with an earth choke would help. One was
found, wired up & tested.
LÄÄÄ(((()ÄÄÄÄÄÄÂÄÄÂÄÄ> L
INVERTER = = = === ³ LOAD
GENNY NÄÄÄ())))ÄÄÄÄÂÄÁÄÄ(ÄÄ> N
=== ===
ÄÂÄ EÄÄÄÄÄÄ(((()ÄÁÄÄÄÄÁÄÄ> E Â
_³_ _³_
/// Genny /// RF Earth
Safety Earth
CONCLUSION
It did work the best of all the filters tested, but the QRM is still above the
GOLD STANDARD of no added noise!
See also buls on "Cheaper Generators", "Regulating 12V Generator Output" &
"Madusa SIP 2300 Generator Repair"
Why Don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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