UTTER HOME is a series of anamalies. It has no connection with the Sutter of Gold Rush fame. It's a winery, not a home. Although located in the heart of the Napa Valley, it does not make wine from Napa Valley grapes.

Shrugging off all that confusion, Sutter Home is among the most innovative and successful wineries in California. Back in the early 1970s, while the most of its competitors were trying to produce as broad a line of wines as possible, Sutter Home reduced its line to a single grape variety. Bypassing those prestigious French grapes chardonnay or cabernet sauvignon, winemaker Bob Trinchero decided to make only zinfandel and only from grapes grown in Amador County.

Neither decision was easy to comprehend at the time. Until the mid-1960s, when Ridge Vineyards began producing a series of wines of awesome depth and power, zinfandel's reputation rested mainly on its utility as a blending wine. Who would have predicted that less than a decade later zinfandel grapes would bring an average of $25 a ton more than cabernet? As for Amador, it was -- and is -- a backwater, a real-life Wild West movie set in the foothills of the Sierra Mountains northeast of Sacramento. One would expect to find a still or two there, but not wine grapes.

"It's ironic," said Bob Trinchero during a recent visit to Washington. "Amador was the grape-growing area most talked about this year at the Barrel Tasting [the annual showcase for California wines at the swank Four Seasons restaurant in New York City. Zinfandels were presented from Ridge, Sutter Home and Montevina, which is in Amador]. "But there are only 700 acres under vine in the county and only 550 of them are producing." Sutter Home takes about 25 percent of the county's annual production, all of it grown on the Deaver Ranch.

"There is no flat land in the entire county," he said. "You have very hot days, over 100 degrees, but at night cool air comes down from the Sierras. There are no mold problems. There's no rain. We start the harvest early, usually the first or second week in September, and we crush for only a month." From winemaker Cary Gott's experiments at Montevina, he thinks sauvignon blanc may do well in the cunty, but is doubtful that other grape types will, and dreams of it being the first -- and only -- appellation in the United States to produce 100 percent of only one variety, the zinfandel.

"Amador zinfandels are easily recognizable," Trinchero said. "There's a peculiar kind of spiciness that's distinctive and they tend to be alcoholic, rich, robust. I made wine from 20 tons of Amador grapes in 1968 and I knew I had the wine I wanted."

The Trinchero family had purchased Sutter Home in 1976 and at one time had sold more than 40 different wines plus vinegar. Bob took over as winemaker in 1960. "I was enchanted with the chateau concept," he said. "Even then I wanted to make only one wine, or maybe one red and one white. But the idea didn't turn on my father or my uncle." In 1971 he had his way. Sutter Home now makes a little more than 50,000 cases of zinfandel a year, half of it red and half of it white (plus a small amount of muscato amabile).

Both the white zinfandel, a salmon-colored wine with enough residual sugar to push it into the medium-dry category, and the muscato, a dessert wine, are quickly sold out in California. The red is distributed here and has become a popular item for collectors. It has the necessary tannin and alcohol to live on for many years and is one of only a few California wines that has been made, year after year, by the same winemaker using grapes from the same vineyard.(Also, it is not costly. The 1975 vintage was only $5.49 this week at one local wine shop.)

Another factor, which may astonish some, is Trinchero's claim that in a blind tasting of old wines "you can't tell a zinfandel from a cabernet.By the time a wine has aged to the point that the identifying fruit is gone, it's the quality of the grapes that counts, not the variety, and the harmony of the wine that makes it stand out."

Last fall a tasting was held here of nine of the 11 released vintages of Sutter Home Amador zinfandel. Only 1969 and 1977 were missing from the progression.

The tasters did find a family resemblance in the wines, but detected significant differences, too. A majority selected the original vintage, the 1968, as their favorite and felt it would continue to develop. The 1974 was also singled out, though it was still hard and rough and had a slightly bitter after-taste. There is little question that with proper storage it will keep for years. The 1973, with a nose of "faded violets," won some support by showing more complexity than the powerhouses that surrounded it. The 1970 was big, deep and smooth with a distinct, berry-like nose. The younger wines were harder to judge, but the 1976, though still clumsy, showed no real flaws and the 1975 had already begun to reveal some roundness and elegance.

During his visity, Trinchero said he has modified his winemaking style "slightly" over a dozen years. The wines were spending up to three years in oak barrels. "I felt the wines woud develop more complexity without so much wood," he said, "so we are finishing them earlier and we are cleaning up the malolactic fermentation earlier. The wine retains more fruit and elegance and isn't so closed in. I think you'll find the '78 an accumulation of what we have been working toward."

However, Trinchero doesn't recommend drinking the '78 for another three years, which points up something the winemaker readily concedes. These Amador wines, and the Montevinas, are not "everyone's cup of tea," he said. They are not picnic wines, nor wines willing to play a supporting role at a dinner party. They demand to be noticed and you may regret their aggressiveness and lack of subtlety.

For such consumers, Trinchero has been experimenting with zinfandel grapes from El Dorado County (a vineyard located only four miles from the Deaver Rance but across the county line). He has come up with a "Beaujolais-style" zinfandel. It has about 1 percent residual sugar and can be chilled. It has not been sold in the East.