[CQ-Contest] Portable Generators

[Garry & Yelena]

Pete Smith wrote:
> 
> This is developing into an excellent thread, but triggers an additional
> question:
> 
> My QTH loses power fairly often in the winter.  This is critical only
> because my well pump is electric, but in some circumstances (including
> CONTESTS) I'd also like to be able to keep the radio running, tho probably
> not QRO ;^}.
> 
> Anyway, in the interest of simplicity and low cost, I had thought to use a
> currently open 220 volt outlet in my garage as the input for my generator
> power.  So if I lose the mains, I would open the main breaker on my power
> panel (isolating my house from the mains), plug the generator into the 220
> outlet (it's a 220 genny, natch) and start it up.  When I see the
> neighbors' lights come back on, I turn off and unplug the generator, and
> then close the main breaker to restore power.
> 
> Anything wrong with this scenario?
> 
> 73, Pete Smith N4ZR
> n4zr at contesting.com
> 
> "That's WEST Virginia.  Thanks and 73"
> 
No, as long as you follow that scenario without exception. I have been
doing that with a 120V unit for many years, with a double-male cord. We
have a LOT of power failures up here in California's Santa Cruz
Mountains. A transfer switch would be the safest way to go, but they are
quite expensive. 

The generator size required depends upon what functionality is required.
Refrigerators and other appliances with capacitor-start motors require a
lot of starting current. I power two refrigerators from a small 1400 VA
Honda, but if they desire to start up simultaneusly, it is a struggle
for the little beast, and once, back in the '89 earthquake, it sucked a
valve.

One problem that arises is with rapidly-varying loads, such as a CW or
SSB amplifier. The dynamic response of the generator's feedback control
system is generally just not fast enough to follow your amplifier's
current requirements, if the amplifier's load requirement equals your
generator's capability. This thread was discussed in detail after Conway
Reef in 1995, where this reality may have contributed to the early
demise of two of the three amplifiers. N6NT and others have found that a
5 kW generator has a hard time with a big Alpha.

Quality really varies widely. One of the big differentiators is the type
of engine. Low-end units typically employ lawnmower-type engines, e.f.
the familiar Briggs & Stratton units. These are fine for occasional
duty, but if the application is critical, you may find them marginal.
Better units use beefy OHV industrial engines.

Each manufacturer typically offers several price-families of generators,
each with a range of power outputs, but few stores carry more than a few
different units. (Even Honda motorcycle/ATV dealerships typically stock
only one unit in each power range.) One interesting hybrid series is
offered by Coleman, probably the largest consumer retailer. They offer
their own generator machine and frame with a Honda engine. This may well
be the best bang for the buck; the 3.3 kVA unit is a real honey, and a
good compromise between price, output, size, noise and utility. W6OA
brought his along for our October CQP effort at 8500 feet altitude in
Alpine County, and it performed flawlessly.

I have been meaning to go get a new 6.5 kVA Generac down at Home Depot,
but some of the comments about spikes and waveforms have me a bit
concerned. My current (small) unit is a Honda. Honday, BTW, is the only
supplier I have seen which publishes noise data---which itself says a
lot. Their units are gorgeous, but pricey. Figure about $2200 typical
for a 5.5 kVA unit, with wheels. No, that's not a portable, but it
certainly transportable. The 6.5 kVA Generac "contractor's unit" is
offered at Home Depot for under $1200---big difference, but undoubtedly
noisier.

I am told that contractors, in fact, have two views of generators. One
camp buys low-end Colemans, uses them until they break, discards them
and buys another--it's a writeoff. The other camp buys rugged units and
keeps them a long time.

Current models tend to provide lots of features--automatic oil-level
shutdown sensors, gas-saving at low loads, bigger tanks, fuel gauges,
GFI outlets, 240/120 outputs, voltmeters.

One item of interest if you plan to run a computer with a UPS
(uninterruptible power supply): UPS's may not work well with the
generator if the generator "floats" its neutral.
-- 
Garry Shapiro, NI6T
160 meters: not a band, but an obsession


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