[UK-CONTEST] Generator reccomendations?

[Peter Hobbs]

Laurence,

These generate at DC and then  invert electronically to produce AC output. 
This has the advantage that the engine doesn't have to run at a specific or 
even a constant speed to produce the required 50 or 60Hz output frequency. 
Also, the full output power can be delivered at DC when needed.  In fact 
they usually run quite a bit faster than traditional generators in order to 
maximise the power to weight ratio, with resultant reduction in engine life. 
We ended up supplying several thousand of this type to MoD, where they had 
to fit into a confined space on a vehicle and meet H&S requirements for 
2-man lift.  However the inverters get quite a hammering and tend to be less 
forgiving of peak loads than rotating machinery.  Reliability is not 
therefore as good as the traditional architecture where the generator 
delivers AC directly.  The EMC performance also compares to a switched mode 
PSU as opposed to a standard linear supply.  We therefore had to jump 
through narrow hoops to get near to meeting the MoD EMC requirement and this 
had eventually to be concessed.

For typical ham use, I would therefore not recommend them for reasons of 
cost, rf noise and reliability.

Peter G3LET

----- Original Message ----- 
From: "Laurence Mason" <laurence at forest-farm.co.uk>
To: <uk-contest at contesting.com>
Sent: Wednesday, May 17, 2006 8:24 PM
Subject: Re: [UK-CONTEST] Generator reccomendations?


> Does anyone know how much better are the new style 'electronic'
> generators. I presume they use some form of switch mode type generation
> but I'm only guessing?
>
> Laurence G4HTD
>
> Ian White GM3SEK wrote:
>> As well as checking the steady voltage as Tom suggests, it pays to take
>> along a few 230V AC dummy loads, and a test lamp to show up any nasty
>> dips or surges as the load comes on and off.
>>
>> Dynamic regulation can be a big problem with QRO multi-band events like
>> VHF NFD, because sooner or later it's going to happen that all four
>> stations go back to TX at the same moment. The gene was really pouring
>> it on, then suddenly the load disappears. The motor over-revs before the
>> regulator can stop it, and the output is heading for 300V. That can
>> easily take out transceiver PSUs as well as rectifier strings in PAs.
>>
>> "Headroom"  is often a good idea, ie a much higher-rated generator than
>> the station apparently needs, but of course you pay for that. An even
>> better idea is an old-fashioned gene with a bloody great flywheel to
>> keep the rpm steady. But there is no way to know how good or bad the
>> regulator is going to be, without actually testing it in the yard.
>>
>>
>>
>
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