Washington's busy news scene just got busier: Channel 20 announced yesterday that starting in early August it will have its own nightly news half-hour at 10 -- produced by NewsChannel 8 . . .

"UPN 20 News at Ten" will be live seven nights a week, and John Hillis, NewsChannel 8 president, said the on-air talent and support staff will come from the cable news network's current staff. He said some reassignments can be expected . . .

WDCA vice president and general manager Dick Williams, Hillis and Robert Allbritton, executive vice president of Allbritton Stations Group, discussed the announcement yesterday from Las Vegas, where they were attending the annual National Association of Broadcasters convention. NewsChannel 8, which provides zoned editions to cable systems in Virginia, Maryland and the District, is owned by Allbritton Communications Co. . . .

Neither Williams nor Hillis would discuss financial details of the project but Williams pointed out that the 24-hour cable network "gets the chance to spread the word about Eight; we get a news program. It's a win-win situation for both parties" . . .

Allbritton said that "this union with UPN 20 further signals that the Allbritton Group intends to remain the dominant provider of electronic news in Washington." The 10 p.m. half-hour won't much affect audiences for Allbritton-owned Channel 7's news at 11 . . .

The WDCA/Eight partnership will be challenging a very popular and (in TV terms) historic newscast at WTTG. Channel 5, then owned by Metromedia, launched the first prime-time newscast in the United States in 1966, and from the start that one-hour 10 o'clock program has been a success in a market where a lot of federal workers, facing an early-morning commute, sign off early. The news at Five often outdraws at least two of the three 11 o'clock newscasts on the ABC, CBS and NBC stations here, and since its launch has often been cited as the most-watched prime-time news in the country . . .

Gene McHugh, Channel 5's new vice president and general manager, is still moving the family from Atlanta and hasn't had a chance to study the Washington news scene yet. He did volunteer yesterday that the WDCA/Eight partnership is "an interesting co-venture and I'm curious about how it will work out" . . .

Williams said the planned newscast "will give Washington viewers a choice, instead of having to spend a whole hour watching the news on WTTG" . . .

"This is a unique partnership," he said yesterday, matched only in the Boston market, where Fox outlet WFXT and New England Cable News produce a 10 p.m. half-hour, seven-day newscast called the Fox 25 News at 10 . . .

Channel 20 is owned by the United Paramount Network, and when the network was launched in January, said Williams, the Washington station produced the fifth-best results of any UPN station in the top 30 markets in the country . . .

Eight months later, he said, "we will add to the full service nature of that {UPN} programming. We went to the people who provide more local news in Washington than anyone. We are extremely excited about the prospects for this new entry in prime time news . . . this will provide both of us with a tremendous opportunity" . . .

Williams said an early August debut is planned "but we haven't homed in on a start date" . . .

A spokesman for UPN said yesterday that while the network currently has no plans to launch a news operation for its affiliate stations, it "expects to definitely contribute an entertainment component to the Washington broadcast on a regular basis, even if we can't give them the latest news" . . .

Now This Public television stations WNVT and WNVC in Northern Virginia will broadcast on a delayed basis Sunday the 8 a.m. Easter service from the Washington National Cathedral . . .

WNVT, Channel 53, will air the program at 11 a.m. Sunday; WNVC, Channel 56, will broadcast the service at noon . . .

The Cathedral has permitted a broadcast of the Christmas morning service since 1950; this will be the first year the Easter service is broadcast. The Right Rev. Ronald Haines, bishop of Washington, will be the celebrant and Dean Baxter will preach . . .

C-SPAN at 6 tonight will mark the 50th anniversary of the death of Franklin D. Roosevelt with a half-hour program that includes a tour of the FDR Presidential Library in Hyde Park, N.Y., and a visit to the Little White House in Warm Springs, Ga., where he died in 1945 . . .

PBS president Ervin S. Duggan yesterday warned broadcasting executives at the monthly International Radio and Television Society (IRTS) in New York of the "profound and destabilizing consequences for every incumbent commercial broadcaster" should efforts in Congress succeed in ending federal funding of public TV . . .

He listed four likely effects on commercial TV should federal de-funding become a reality, including "the creation of a new commercial competitor in virtually every television market in the country" and "increased pressure on commercial broadcast, from Congress and the FCC, on matters of television content" . . .

He also forecast "the economic failure of many public television stations and their sale to commercial broadcasters, increasing the number of for-profit commercial licensees and diluting the value of incumbent commercial broadcasters" and more UHF-VHF swaps . . .

Duggan said, "We in public television believed it would be a moral outrage to force our enterprise, which has honorably served families, children, teachers and students for decades, to abandon our mission and live under the imperatives of the commercial marketplace" . . .

He also quoted at length from Thomas Hardy's "The Ruined Maid," as well as John Donne's ever-popular "Devotions Upon Emergent Occasions," verses cited infrequently at IRTS lunches this close to the end of the regular season . . .

NBC's "Meet the Press" is flying to Russell, Kan., this weekend to interview Sen. Robert Dole, the Republican Party's most recently announced candidate for president . . .

The Senate majority leader will be interviewed Saturday (for the Sunday a.m. telecast) before an audience of 500 at his hometown high school, now called Ruppenthal Middle School. The regular Round Table will be scrapped so the audience can question Washington Post columnist David Broder, NBC Capitol Hill correspondent Lisa Myers and "Meet the Press" moderator Tim Russert . . .

ABC Entertainment confirmed yesterday that plans for a three-week test run of a sitcom called "Buddies" starting next Tuesday have been scrapped so the producers can reshoot the pilot . . .

The sitcom is produced by Wind Dancer Production Group, which also produces ABC's most popular series, "Home Improvement." That's why the "Buddies" were going to get a tryout in the coveted 9:30 time slot immediately following "Home Improvement." It is also why ABC Entertainment president Ted Harbert and Matt Williams, co-creator of the show, stress that the series is still very much a candidate for the 1995-96 schedule . . .

ABC says in lieu of "Buddies," a rerun of "Roseanne" will air at 9:30 on April 18, followed by repeats of "Ellen" on April 25 and May 2. "Grace Under Fire" is scheduled to return to the coveted slot on May 9 to help out in the May ratings sweeps . . .

"Buddies" is about two best friends, one white and married (Jim Breuer), the other African American and single (Dave Chappelle), running their own small film and videotape company . . .

CBS edged out NBC in the Monday night ratings battle with a repeat of "Murphy Brown," compiling a 13.5 rating and a 21 percent audience, and a new episode of "Cybill" averaging a 13.0/20 . . .

The series premiere of "In the House" did an 11.1/18 for NBC . . .

The movie "Arachnophobia" averaged a 10/4/17 on ABC . . .

Locally, "Murphy" did a 17.3/27 and "Cybill" a 15.4/24 on WUSA; on WRC, "In the House" averaged a 12.9/20 and "Arachnophobia" did a 9.6/15 on WJLA . . .

"Star Trek: Voyager" produced an 8.9/14 on WDCA . . .

TV RATINGZZZZ

Following are the top 20 network prime-time shows last week, ranked according to the percentage of the nation's 95.4 million TV households that watched, as measured by the A.C. Nielsen Co. A share represents the percentage of actual sets-in-use tuned to a particular program when it aired.

.... Rating ................................ Share ... Network

1 ... 24.4 .. ER ............................. 40 ....... NBC

2 ... 21.3 .. Seinfeld ....................... 34 ....... NBC

3 ... 20.5 .. Friends ........................ 32 ....... NBC

4 ... 19.3 .. NCAA Hoops Final ............... 30 ....... CBS

5 ... 18.2 .. Home Improvement ............... 28 ....... ABC

6 ... 17.0 .. Grace Under Fire ............... 28 ....... ABC

... 17.0 .. NYPD Blue ...................... 28 ....... ABC

... 17.0 .. Ellen (Tues.) .................. 27 ....... ABC

9 ... 15.6 .. 60 Minutes ..................... 28 ....... CBS

10 ... 15.3 .. Coach .......................... 24 ....... ABC

11 ... 14.5 .. PrimeTime Live ................. 25 ....... ABC

12 ... 14.0 .. Hope & Gloria .................. 24 ....... NBC

13 ... 13.7 .. NCAA Hoop Post-Game ............ 22 ....... CBS

14 ... 13.4 .. Steel's Vanished ............... 20 ....... NBC

15 ... 13.1 .. 20/20 .......................... 25 ....... ABC

16 ... 13.0 .. Mad About You .................. 24 ....... NBC

17 ... 12.8 .. America's Funniest Home Videos . 20 ....... ABC

18 ... 12.7 .. Ellen (Weds.) .................. 21 ....... ABC

...... 12.7 .. Ten Commandments ............... 21 ....... ABC

...... 12.7 .. Thunder Alley .................. 21 ....... ABC

ABC and NBC tied for first place in the penultimate week of the regular prime-time season, at least in the household count. Both averaged an 11.4 rating and a 19 share, compared with 9.9/17 for CBS and a 6.5/11 for Fox . . .

UPN averaged a 2.8/4 while WB network did a 1.8/3 . . .

ABC, which has the ratings crown wrapped up, was No. 1 among adults 18-49, men 18-49 and total viewers. With one week to go, ABC has a 38 percent advantage over CBS in the adults 18-49 demographic, a 33 percent spread over Fox, and a 6 percent advantage over NBC . . .