I think this is an excellent topic for hams to discuss. Let me give some of my background, but please keep in mind I am not tyring to push any name brands or specific products here.
My name is Chris Smith and I am a Power Generation Service Engineer with a diesel engine distributor in Sparks, NV. I have worked in and around two-way radios for most of my career. My father, W7HRY, is a long time ham and is thrilled I have joined in. My primary interest in ham radio is QRP and, you guessed it, power generation and the development of remote, off grid repeater sites.
I think one of the best parts of being a ham will be exchanging info with other hams. Let's face it, I don't know squat about homebrew HF stuff but hope to learn alot from others. One thing I do know a fair amount about are generators and the related switchgear. I sure don't know it all,but I can probably find somebody in the industry to answer your question if I can't. BTW, everybody including me has an opinion and, one of those, and they both stink...
I will try to stay on topic here as much as possible. If you have a specific question please e-mail me at nvhammerman@prodigy.net. In the interest of security please include your call in the header and avoid using attachments. I can then summarize the answer and post it here. Perhaps the folks at e-ham might consider this as a seperate topic in the future.
Now with the answers/more confusion:
The fact is all small gasoline portable generators are pretty mediocre. Some are better than others, but they are few and far between. So lets compare some generator basics.
First off, in the industry we call them "gensets" regardless of size or fuel. Secondly the equipment that actually connects the AC output to your stuff is called "switch-gear" (read in extension cord here!?!) so please excuse my use of jargon/lingo here.
Gensets typically use 4 pole alternators or 2 pole alternators. 4 pole ones run at 1800 RPM and 2 pole units run at 3600 RPM. Generally, the faster an engine runs, the more fuel it uses, the more noise it makes and the sooner it wears out. Most small gas gensets run at 3600. This allows the use of small inexpensive engines. Manufacturers, including the company I work for, call this cost effective engineering... And they sell it as "lightweight, portable, inexpensive....." You know what I mean.
Enter the world of 1800 RPM units. These gensets are usually stationary mounted and not very portable. They often are run on diesel fuel and can last for 15,000 to 20,000 hours of continuous duty. They are also very expensive.
As a result most of us consumer types are left to choose from the gensets at Costco or Home Depot.
"Great, Chris, I guess I'm just screwed now..."
Well, kind of, you just have to shop around to find the lesser of all evils.
Shopping points:
When it comes to the engine don't lose much sleep on the brand. Try to purchase one that has overhead valves (OHV) because they don't carbon up as bad.
Be carefull of units that are "Powered by:" because you often pay for the engine makers name and wind up with an electrical end that is junk. Honda, Kawasaki, and most Japanese units are pretty good. Just for the record, I would not buy an Onan/Cummins portable based on the fact I have seen a lot of engine failures.( if my boss happens to read this I will be looking for a job...) If you are willing to spend a couple hundred bucks more at a local full service specialty shop ie: "Joe's Outdoor Power Equipment" you will probably have better luck than the box stores. Our buddy "Joe" will probably be willing to let you hear the genset run "UNDER FULL RATED LOAD" to compare noise levels. You just won't get that service at "the depot", sorry guys, stick with lumber.
Don't sweat what type of voltage regulation system the unit has. None of the portables use true automatic voltage regulators. Most use some type of capacitor system and cause radio noise, you get what you pay for...Look for units that offer some type of AC output voltage adjustment since these usually use a shunt type regulator versus capacitors.
For field day use or RV's, sizing of 3500 to 6000 watts will probably work OK. For just field day types of ops, get one of the ultra quiet "suitcase" units. 800-1000 watts will run most everything in the shack, with the exception of a 1500W amp of course!
For large club field day events, check with a local genset dealer or rental yard. They will be able to set you up with a 30kw or so unit to provide power to all the ops on site. Here's a hint, ask if they would be willing to donate use in the interest of serving the community. Most salesmen welcome the "free advertising" since the equipment just sits most of the time.
Regarding connection to your home for power outages:
If you don't have the proper, code approved, and properly installed switchgear (transfer switch) DO NOT "RIG" IT UP. At best your genset will get burned up and you or someone else can be killed at worst. I won't go into anymore disertations here. Please post any questions. If somebody wants to run a UPS or large pump, please post your "load info" and I will try to help out.
The ARRL HANDBOOK has a pretty good section on AC theory that can be extrapolated for generator understanding. Also check out some of the independent power/off-grid/solar web sites. They usually offer some genset load calculation guidelines you can download. Just a word of caution: most of their "free advice" is geared to promoting their "product of the month" so ask them lots of tough questions about their products if you buy mail order.
Thanks, and sorry for the "windy" post. Go see "Joe"
73, KD7PKO