Good old American ingenuity, the kind that took us from the steam engine to the space shuttle, has found a home on Wall Street, where the wizards of finance grind out new kinds of investments daily.

One of their more novel ideas has brought together E. F. Hutton & Co., the national brokerage house, and Planning Research Corp. of McLean, a $360 million Big Board company that employs 5,600 people and, among other activities, handles major contracts for the Defense Department and the National Aeronautics and Space Administration.

Hutton and PRC devised a plan that offers investors the income tax write-offs of a limited partnership and the chance to use their money to develop new high-technology products. The plan also offers the hope of substantial royalties if the products succeed. As with most new limited partnerships, the size of the "if" factor may not be immediately clear.

The partnership, called Hutton/PRC Technology Partners 1, was formed in late 1983. It raised $25.6 million and thus far has invested $19.5 million in specific research and development projects at seven high-tech companies. A. S. (Ernie) Gianoplus, who is PRC's director of corporate development, calls the idea a new version of venture capitalism, in which investors fund individual "product ventures" instead of whole companies.

With their first program under way, Hutton & PRC now are selling their second partnership -- this one for $35 million. If fully subscribed, Hutton/PRC 2 can go as high as $50 million. The tax benefits and royalty arrangements of the second partnership will be similar to the first, said Gianoplus, who foresees even more such partnerships in the future.

The seven investments made by Hutton/PRC 1, chosen from among 230 proposals, range from a $1.6 million investment to a $5.3 million investment and are devoted to such esoteric projects as:

* Developing an X-ray source to be used by manufacturers of wafer alignment equipment for the semiconductor industry.

* Developing for lawyers a new type of litigation support system based on microcomputer technology.

* Developing an integrated bar code data collection and scanning system for industrial applications.

To participate in the Hutton-PRC partnerships, a qualified investor must put up a minimum of $5,000 for 10 units. Investment is limited to people with a net worth of $150,000 (excluding home, furnishings and autos), or those with a net worth of $50,000 (with the same exclusions) and a taxable income of $50,000.

On a $5,000 investment in Hutton/PRC 2, an investor is likely to be able to deduct (as losses) from his income tax about 80 percent, or about $4,000, over a three-year period. The amount of actual tax savings will depend on the investor's tax bracket. Then, if the partnership met its goal of generating royalties of at least three times the investment, the investor would get about $15,000 over an eight-year period, Gianoplus said. The royalties would be treated as long-term capital gains and taxed at a maximum of 20 percent.

The high-tech company in turn gets, say, a $1 million infusion of cash to create a product. It doesn't have to sell stock, borrow money, report experimental losses or do anything else that might affect its balance sheet, earnings or stock price. The venture capital pays for project expenses.

For its part, the company, if it is also the product licensee, agrees to pay royalties to the partnership. The product, if successfully marketed and distributed, will benefit the high-tech company, which also may be able to buy out the partnership's interest.

E. F. Hutton, which suggested the creation of the partnership, benefits in two ways. It sells the units, earning a commission on sales. Commissions on Hutton/PRC 1 totaled more than $2 million. Then there is the distribution of royalties. In Hutton/PRC 1, investors will get all royalties until they equal the $25.6 million they invested. On subsequent royalties, investors will get 80 percent and Hutton and PRC 10 percent each.

The expectation is that Hutton/PRC 1 will add $4 million to $5 million to PRC coffers, said PRC President John Toups. From his standpoint, Toups added, the partnership also gives PRC a window into high-tech development and some national publicity, as a legion of Hutton brokers go around selling and talking about Hutton/PRC.

Hutton/PRC 2, Gianoplus said, will be a bit different. There will be a greater number of smaller projects that can be completed in 12 to 18 months instead of in 24 to 30 months. One reason is that a 1984 change in the tax law limited research and development deductions to amounts actually spent each year rather than to funds merely committed. Another reason, Gianoplus said, is that the speed of technological change makes shorter projects more saleable.

In return for their product investments, the partnership will ask each company handling a venture project to give low-value warrants -- a form of equity -- in their company. Of course, the warrants will be exercisable later at a much higher price. The effect would be to give the partnership back its investment and, perhaps, facilitate the payment of royalties.

What can go wrong and spoil these scenarios? The partnership's prospectus, like most such documents, is replete with "risk factors" and reasons why the idea won't work. The most likely are that after a product is developed, technology may change, marketing efforts may fail or market conditions may change. Thus far, however, E. F. Hutton and PRC think they've got a good thing going.

Perpetual American Bank stock, which went public at $7.50 in August and was selling at $8.75 bid-$9 asked in November, climbed to the $13 range last week, as the bank continued its efforts to guarantee that fiscal 1985 will be a profitable year. If so, it would be only the second black-ink performance in the last six years. The stock closed Friday at $13.25 a share bid and $13.50 asked.

The latest burst of enthusiasm for Perpetual American stock came on news that the bank would add $7 million ($1.03 a share) to earnings by selling a vacant parcel of land in downtown Washington. Actually, the stock moved up $1 the day before the news was announced. The bank still has its building at New York and Pennsylvania avenues NW on the market -- at a price of $35 million. Sale of the building also would have a favorable impact on earnings.

In case you've been wondering what happened to Hemokinetics, a Northern Virginia company founded in 1981 to produce medical devices, this is the not-so-happy story: The company moved from Vienna to Madison, Wis., in September, according to President William N. Reining. Madison is Reining's hometown.

Hemokinetics stock, Reining said, was dropped from the rolls of the National Association of Security Dealers because the firm's assets fell below $750,000. As a result, the stock is now found on the "pink sheets," the home for stocks not listed on the exchanges. The shares, sold at 60 cents each in 1981, recently were priced at 1 cent bid-4 cents asked.

The company, which raised $2.7 million in its 1981 public offering, had liabilities of $250,000 and assets of $380,000 in November, Reining said. The firm still is making and selling a calorie counter called CALTRAC.