Will America buy the generic hamburger?

While Burger King and McDonald's haggle over the fine points of Americans' preference in hamburgers - grilled or broiled, Big Mac or Whopper - John Galardi's instinct is that they simply want their burgers cheaper.

So he's giving fast-food fans a generic, no-frills hamburger at the Original 39 Hamburger Stand. Judging from the steady stream of customers through his Santa Ana Hamburger Stand on a recent evening - in head-on competition with a McDonald's across the street - there is a big appetite for his little burgers.

The Hamburger Stand chain now has 11 stores, and new ones are cropping up at the rate of about two a week in Western states. Mr. Galardi, who also is the founder and owner of the Der Wienerschnitzel fast-food chain, expects nearly 100 to be operating by year end. Several of the new stores have been converted from Der Wienerschnitzel outlets. Business at those outlets has picked up so quickly that the number of employees has increased from 10 to 40 per store, reports Mr. Galardi, who won't divulge sale figures.

(Officials at McDonald's, whose cheapest hamburger is 49 cents, wouldn't comment on the new competition. And certain Burger King outlets have been offering hamburgers as cheap as 39 cents in recent weeks.)

The Hamburger Stands are the ''K marts of fast food,'' designed to fill the void left by the upscale burger, says Mr. Galardi. For 39 cents, he says, you won't get the designer-labled styrofoam bubbled packing, secret sauce, ceiling fans, and potted plants.

What customers do get is a US Department of Agriculture-approved 100 percent beef hamburger wrapped in the white-with-black-stripe packaging used in supermarket generic products. One pound of ground meat produces 10 patties. The burger has ketchup and mustard, but no lettuce. Other no-frills offerings are a cheeseburger for 49 cents, a bacon cheeseburger for 75 cents, a double cheeseburger for 95 cents, french fries for 39 cents, and sodas labeled ''drink'' for 39 and 49 cents.

''It's not bad . . . it compares with McDonald's,'' says Barbara Donnelly, a postal worker who has just fed herself and her two daughters for under $3. Why was she there? ''Where else are you going to feed your kids when you've got less than $5 in your wallet?''

And that's precisely Galardi's point. ''Everybody pursued the baby-boom generation as it exploded through each age and each trend,'' he explains.

''But there's a big market that's forgotten, like the 10 percent who are unemployed, the elderly on fixed incomes, and teen-agers,'' says Galardi, who claims his is the first fast-food chain to target that market exclusively.