Based on QST articles, here is what was indicated for Vietnam:  In Feb. 1966 the Vietnam government gave permission for only Bill Porter, K1YPE/XV5, to operate.  He also used XV5AA.  No other authorizations were given at that time.  He was assistant ambassador to Vietnam and eventually left.  In January, 1973 only XV5AC was authorized to work stations in other countries.  In June 1974 XV5AA and XV5AB were also granted permission to operate.  These were the only exceptions to the banned list.  There have been other special permissions, though.  In August, 1958 I worked W3ZA/3W and was given DXCC credit.  He also operated as XV5A.  After the end of the Vietnam war the 3W and XV stations slowly started to appear.

It was a similar situation in Thailand with bans that were off and on.  In March 1957 I was given DXCC credit for HS1A, a USAF major stationed in Bangkok.  Cambodia was finally on the air to work in mid-1972 when XU1AA appeared after many years on the banned list.

Here are the QST references for Vietnam:

Feb. 1966, p. 67.  Banned countries list.  No changes to list of banned countries.  However, a footnote states:

"K1YPE/XV5 has permission for international communications from the U.S. and Vietnamese administrations and is authorized to handle third-party messages with U.S. amateurs."

Jan. 1973, p. 81.  Banned countries list.  Notice from Vietnam.  Full quote.

Amateur licensees are warned that international communications are limited by the following notifications of foreign countries made to the ITU under the provisions in Article 41 of the Geneva (1959) Conference.

The Director General of the Posts and Telegraphs Department of Vietnam has notified the ITU that there is no objection to communications between amateur stations in other countries and XV5AC.  However, communication with other amateur stations in Vietnam (XV or 3W8) is forbidden.  Canadian amateurs may not communicate with Cyprus, Gabon, Iraq, Pakistan, Turkey, Khmer Republic (except XU1AA), Vietnam, Libya, and Yemen.  Prefixes to be avoided by Canadians are AP TA TR8 XU XV YI ZC4 3W8 4W 5A.

 End quote.

June 1974, p. 10.  League Lines states "The Republic of Viet Nam has announced that it has no objection to communications between stations XV5AA and XV5AB and amateur stations in other countries.  These stations join XV5AC on the "okay to work" list for amateurs."

Tnx W6YA

 

United States Military Assistance Command. Vietnam 
APO San Francisco 96243 

Dear Mr. Green: 

After many years with no amateur radio activity in 
the Republic of Vietnam the recent activation of an 
amateur radio station here has caused a great deal of 
interest in the ranks of amateurs worldwide and espe- 
cially among those amateurs now in, or about to come 
to Vietnam. ARRL bulletin #40, other published no- 
tices, and on-the-air discussions have caused this head- 
quarters to receive an unprecedented number of re- 
quests for information concerning authorization to op- 
erate here. Answering these requests imposes an added 
burden that can be ill afforded. It is the purpose of 
mis letter to explain the current status of amateur 
radio in the Republic of Vietnam and ask that you 
publish this Information in 73 Magazine. 

For many years the Republic of Vietnam has been 
torn by strife and it was in this setting shortly after 
independence was attained that amateur radio was 
banned and an exception to amateur operation was 
filed with the ITU. Until late in 1965 there was no 
legal amateur operation in this country. At that time 
the Government of Vietnam extended the privilege of 
amateur operating authorization to Deputy Ambassa- 
dor William J. Porter, K1YPE, as a courtesy to a high 
ranking United States diplomatic representative. Si- 
multaneously, action was initiated to withdraw the ex- 
ception to amateur operation filed with the ITU to 
enable other countries to recognize his operation. 

Ambassador Porter has been authorized by the Gov- 
ernment of Vietnam to vise the call XV5AA and there 
is no restriction on third party message and phone 
patch traffic. However, since other governments have 
not yet been notified of this action by the ITU. until 
they are Ambassador Porter is using the portable call 
K1YPE/XV5 for U.S. amateur contacts at the request 
of the FCC. His use of this call will cease when the 
ITU notification is received and he will then com- 
mence using the call XV5AA. He is already using 
XV5AA, however for contact with non-US amateur 
stations- v 

There have been some questions received concerning 
the prefix used for Ambassador Porter's call sign. The 
exclusive use of 3W8 for amateur stations seems to 
have been implied by certain published listings in 
which only 3W8 appeared, but this is incorrect and 
other listings correctly show both 3W8 and XVS.
CQ January 1968 reports that the K7LMU/3W8 operation took place after clearing the activity with the FCC to lift the ban, at least temporarily.
 Tnx 5B4AHJ

 

Info courtesy of W6YA, 5B4AHJ