Working Group 2 was scheduled to have a joint meeting in Moscow early in May, and MSC believed this session would provide an opportunity to test the recent agreements reached in Moscow. On 10 April, three days after his return to Houston, Lunney sent a telegram to Bushuyev. MSC would call Moscow on "Friday, April 14, 1972, at 7:00 AM Houston time, 4:00 PM Moscow time" to discuss the agenda items outlined in this telegram.53 The first attempt to establish a telephone connection with the Professor was unsuccessful, because the Americans tried to tie Lunney, who was at Kennedy Space Center (KSC), into the line for a three-way conversation. On  the second try, only the Houston people made the connection with Moscow. After initial greetings to Bushuyev, the remainder of the conference call was conducted by the respective Working Group 2 chairmen, Legostayev and Cheatham. They agreed that the Americans should visit Moscow on 15-20 May. Cheatham proposed that the May agenda include discussions of communications and television links between spacecraft, an exchange of data on the Apollo and Soyuz control systems characteristics, and further study of the docking target system. After a discussion of the radio frequencies to be used between spacecraft and between ground control centers, the two men answered each other's general questions. While the telephone connection was still less than satisfactory, this second telecon was more successful than the first and helped both sides prepare for the upcoming meeting, the starting date of which was later advanced to the 10th.54
Group 2's spring meeting was an important one in which a full agenda was addressed and progress made on a number of key issues. While discussion continued on the external lights, docking targets, coordinate systems, and other topics related to docking, the main subject was spacecraft-to-spacecraft radio communications and distance ranging. At previous meetings there had been considerable discussion about radio frequencies: Would each side exchange radio equipment for its frequency or give the necessary data to the other group so they could build the equipment? The Soviets had advised NASA at the November-December 1971 meeting that they would continue to use the 121.75-megahertz (MHz) frequency for their voice communications. The Americans in turn advised the Soviets that they had yet to determine which frequency they would use but would do so by March 1972.55
While the obvious choice would have been to continue using the Apollo voice frequency, the Department of Defense was eager to have NASA abandon its use of frequencies in the 225- to 400-megahertz bands. The Apollo voice frequency had been loaned to NASA in 1958 by the military for Project Mercury, and they had been pressing the space agency since then to give it up. A 1968 agreement between NASA and the Department of Defense called for NASA to withdraw from all military frequencies by 1975. In an effort to save from $500,000 to $700,000 for new radio equipment, MSC had worked with NASA Headquarters during early 1972 to obtain Department of Defense approval for use of the 259.7 and 298.6-megahertz frequencies for a joint Soviet-American test project. This agreement had been tentatively reached just before the American delegation left for Moscow.56
A second issue that remained to be resolved both internally and with the Soviets centered on the "build versus exchange" question. At first glance, it seemed that it would be simpler for each country to give its radio  equipment to the other for installation into their respective spacecraft. On the American side, this exchange appeared to be complicated by the fact that the Apollo VHF transceiver also embodied another assembly that provided a backup distance ranging capability between the CSM and the lunar module. This little unit, called the Range Tone Transfer Assembly, had been added after the original design of the transceiver in 1962, and it was rather sophisticated in terms of its solid-state circuitry. There was some concern at NASA and in the Defense Department that providing this hardware to the Soviets for a joint mission might also constitute a giveaway of valuable technological information. This problem of possible technology transfer had not yet been resolved by the time of the May meeting of Working Group 2. The Americans asked the Soviets to postpone a decision on radio transceivers, and they agreed to do so.
This "exchange-build" issue serves to illustrate how difficult the negotiations could be. Just defining the nature, scope, and implications of the many technical considerations involved in compatibility was a complex, time-consuming task, recalled R. H. Dietz of Group 2. And this process became even more complicated when neither side had a clear understanding of its own goals for a particular topic. In preparing for the negotiations, the Americans had drafted three Interacting Equipment Documents in two versions - the first could be used if a decision was made to exchange equipment, and the second was ready if they decided to build. While this applied to only three of the twenty-six documents that NASA took to Moscow, everyone would prefer to avoid double efforts.57
Not all the communications raised at the May meeting proved as thorny as the "exchange-build" issue. Considerable progress was made on the topics of cable links between spacecraft for voice communications after docking and communications systems for future missions. Donald Cheatham, the American chairman of Working Group 2, felt that the meeting was basically successful. The two sides had sufficient time to work out the points of agreement, and as a consequence they got all of the primary issues clearly defined and resolved. He felt that this session was a good indication on the Working Group level that there would be no irreconcilable differences in working out the technical aspects of a joint mission. The way seemed clear for the government-to-government agreement at the May Summit in Moscow.58
53. TWX, Lunney to Bushuyev, 10 Apr. 1972.
54. Lunney to Kraft, memo, "Minutes of the Apollo/Salyut Test Mission Telecon Held April 14, 1972," 26 Apr. 1972; and Donald C. Cheatham to Lunney, memo, "Telephone Conference with USSR Working Group No. 2 on April 14, 1972," 19 Apr. 1972.
55. "Working Group No. 2, May 11-17 - Moscow 1972, Minutes of Meeting on Assuring Compatibility of Rendezvous and Docking Systems of USA/USSR Spacecraft," 17 May 1972; and interview, R. H. Dietz-Ezell, 28 June 1974.
56. Jack T. McClanahan to Robert N. Lindley, memo, "Voice Communication Frequency Assignments - US/USSR Cooperative Mission," 15 Feb. 1972; C. C. Kraft to D. D. Myers, 22 Mar. 1972; D. D. Myers to C. C. Kraft, memo, "Frequency Assignment and Rendezvous and Tracking System," 3 Apr. 1972; "USA/USSR Voice Communications System Frequency Selection Briefing Presented to M/Mr. Myers at Headquarters, April 5, 1972 by EG/D. C. Cheatham," 5 Apr. 1972; Leroy Roberts, "Minutes of Meeting - Voice Communication Frequency Assignment Meeting," 5 Apr. 1972; D. C. Cheatham to Robert A. Gardiner and G. S. Lunney,memo, "USA/USSR Voice Communications System Frequency Selection Meeting with Mr. Dale Myers, M/Associate Administrator Manned Space Flight," 6 Apr. 1972; and D. D. Myers to distribution, memo, "Frequency Assignment," 8 May 1972.
57. "Working Group No.2 Minutes of Meeting," 17 May 1972, with "Appendix: The List of Documents Exchanged by the Sides at the Working Group No. 2 Meeting of May 11-17 1972"; and interview, Reinhold H. Dietz-Ezell, 30 July 1975.
Cheatham-Ezell, 24 July 1975.