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Author Topic: Generator for 500W amp?  (Read 361 times)

G4AON

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Generator for 500W amp?
« on: April 10, 2021, 11:22:11 AM »

I currently have a Yamaha EF2800i inverter generator. It powers my portable setup easily, running both an Elecraft KPA500 amp and transceiver.

A lighter “suitcase” generator, such as one of the 2KVA inverter types, look like they may suffice and a 10Kg reduction in weight isn’t to be sniffed at.

Running time is not really an issue, it is whether a 2KVA generator can realistically cope with a 500W output linear on CW?

Your thoughts appreciated.

73 Dave
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VE3HIX

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Re: Generator for 500W amp?
« Reply #1 on: April 10, 2021, 11:38:56 AM »

Without looking up the exact specs, Your 400 watt output linear amp probably needs 800 watts of AC input, and your 100 watt output transceiver probably needs 200 watts. Total AC input would be around 1000 watts or so. A 2KW inverter generator would be fine. I don't know whether it would work properly in the "econo" mode on CW where it runs at idle until power is required, but it would certainly work in the "normal" mode. Stay with a quality product. Change the oil every 72 running hours. You get what you pay for.

Cheers,
Bob
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K0ZN

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Re: Generator for 500W amp?
« Reply #2 on: April 10, 2021, 11:23:44 PM »

I worked with generators a good deal in the Army Signal Corp. A generator will be most frequency and voltage stable and provide the best regulation if you have a modest "base load". This would be especially true of a station operating CW. I would suggest a small base load of 100 to 200 watts in a purely resistive load like a lightbulb. Your 2KVA genset should still be quite happy as the max load will still be well under ratings and CW is about a 40% duty cycle.

For whatever it is worth: I have a 6KW portable genset and I have found that petrol quality is a factor in frequency/voltage regulation. I can't explain why, but I do know from some tests that frequency/voltage stability is best when I use premium NO Ethanol fuel. The difference between 87 octane with Ethanol and pure petrol 91 octane was not huge, but it was detectable. I am not familiar with UK petrol ratings, but I would recommend a top quality NO Ethanol fuel. Hopefully, you do not have Ethanol in your fuels; it is bad stuff for small engines and can cause all manner of corrosion and damage, especially in storage if not managed with a fuel treatment. Fuel problems are, by far, the primary cause of engine issues in small engines that do not run a lot. It is also advisable, especially for a genset to be used in emergencies, to remove the fuel once a year and replace it with fresh fuel. Obviously, if you run the unit a lot, that is not necessary.

  73,  K0ZN
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G4AON

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Re: Generator for 500W amp?
« Reply #3 on: April 11, 2021, 04:20:26 AM »

Thanks for the replies. My 2800 KVA generator does cough a little running 400W of CW when it is on economy mode, which is understandable and not how I use it. SSB on eco mode is pretty good. The generator dates from 2006 and still runs like a sewing machine.

My generator is run regularly and I always turn off the fuel to let it run dry. I try to not leave much fuel in the tank so it is mostly fresh when topped up to use... it also keeps the weight at a minimum for carrying!

I don’t think our fuels currently have much alcohol added, but there is a constant push towards “greener” fuel. I will bear it in mind for the future.

73 Dave
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