Former Fairfax board chairman John F. Herrity has sent a letter to 41,000 Republican households urging voters to defeat a Nov. 6 referendum that would allow local governments to pay for transportation improvements with pledge bonds.

The mass mailing is a clear sign that Herrity, who was defeated by Democratic slow-growth champion Audrey Moore in 1987, hopes to revive his political fortunes and recapture his old post in next year's Board of Supervisors elections.

Herrity's solidly pro-development philosophy, espoused during his three terms as chairman, was vilified by Moore in the last election, which she won with 58 percent of the vote. Herrity's reelection effort also was severely damaged by a string of speeding tickets and other driving infractions.

The mailing, however, appears designed to raise Herrity's standing in his own party in anticipation of a primary battle with Supervisor Thomas M. Davis III (Mason), who also is seeking the GOP nomination to challenge Moore in November 1991. Herrity's said his letter was sent yesterday to every household with a resident who voted in last year's Republican gubernatorial primary, the same voters who probably will choose the party's candidate for board chairman.

"This is pro-Jack Herrity, not anti-anybody, except the board majority," Herrity said. "It's certainly not directed at Tom or Elaine McConnell" (Springfield), the only Republicans on the nine-member board.

Statewide, there are four referendums on the ballot that ask voters whether the state Constitution should be amended. Herrity's letter attacks the third proposed amendment, which would permit counties and cities to issue transportation pledge bonds without voter approval. An identical referendum would permit pledge bonds for the state, which has a long opposed debt-financing in favor of pay-as-you-go capital construction.

If approved on Nov. 6, beginning next year local governments could raise up to $2 billion statewide for transportation -- including $360 million in Fairfax -- without voter approval.

"This new amendment would strip away our right to vote," Herrity's two-page letter says. "You and I have been handed unprecedented tax increases -- at a time when the economy is on the decline. And Fairfax County borrowing is at a dangerously high level . . . . Please join me in voting this down."

Included in the mailing is a return postcard addressed to Herrity that could give him a potent Republican mailing list for future fund-raising efforts.

Herrity said the mailing cost about $8,000 and will be paid for by Friends of Jack Herrity, the fund-raising organization for his 1987 campaign.

"Jack was always bullish on development and timid on transportation," said Martin Machowsky, a spokesman for Moore, who was out of town yesterday. "He left us with an enormous bill to pay for the transportation problems he created." Machowsky added that Moore "has taken the lead in holding the line on taxes and spending in the current period of economic uncertainty."

Herrity, like Davis, appears to be favoring tax-and-spend pocketbook issues in the coming campaign. However, Herrity's strategy evidently is to paint Davis as a Republican clone of Moore. In comments this week, Herrity blasted both, saying they are having "a death-bed, election-year conversion, Audrey on taxes and Tom on taxes and growth, and it's a disgusting spectacle to watch."

"I'm sorry Mr. Herrity is attempting to go negative against other Republicans so early," Davis responded yesterday. "I think it shows that his own polls must show him running substantially behind Mrs. Moore and myself."

Davis, who said he also opposes local pledge bonds, said he voted against the board's Democratic majority on tax and spending issues more than 30 times. "I expect that to be an issue next year, and I expect Jack's veractiy to be an issue."

While many civic groups oppose the pledge bond referendum, most business groups favor it. Nonetheless, no business leaders would criticize Herrity on the record.