As the thread, in Wanted and For Sale, where we were recording information about the 11-99 has been locked I decided to create a dedicated thread here in General Discussion.

I have added another 6 serial numbers to the previous list, which has now been copied to here:


Serial Numbers:
189 - 6 Aug 1965 on transformer
1229 - 27 Oct 1965
4969 - (date?), 6V4, no groove on back, ARTS&P cyan AC075205
6462 - 6 Sep 1967
8118 - 1 Dec 1967
10036 - 24 Apr 1968, 6v4 rectifier, dates on the IF cans. 6v4, 2 wire, paper caps 20 and 25μF electro's
10835 - 30 May 1968, 6v4 rectifier, 2 wire mains cord, mix of mustard and paper caps. 30 and 40μF electro's
11148 - (date?), 6V4 rectifier
16310 - approx Mar 1969 - 6V4 rectifier and caps marked 059 and 079, ARTS&P label AA 879187
17412 - (date?), 6V4 rectifier, wax caps marked xx6 and ARTS&P label AA 998629
19039 - 26 Aug 1969, 6V4, groove on back, ARTS&P cyan AB697937
20686 - 13 Nov 1969, silicon rectifier, 3-wire mains cord, earthed chassis, ARTS&P label AB 772563, cream cabinet
20741 - 13 Nov 1969 on power transformer
20893 - 18 Nov 1969 on IF can - silicon diode rectifier
23428 - 27 April 1970 on power transformer, silicon diode rectifier
24787 - 4 Aug 1970, silicon diode rectifier
27508 - 15 Oct 1971
33319 - (date?), silicon diode rectifier
34968 - 24 Mar 1972
35788 - Apr 1972 (Type BY126 diode)
38406 - 19 July 1972
41218 - 15 Mar 1973
42422 - 5 May 1973, silicon rectifier, 3 wire mains cord
45967 - 6 Mar 1974
46532 - 11 May 1974, silicon diode rectifier, groove on back, no ARTS&P label (*)
46591 - 25 Apr 1974
47210 - 16 June 1974
47874 - 2nd July 1974, silicon diode rectifier, 3 wire cord with the "notch", black dial face, mustard caps 20 and 25μF electro's.

-------

(*) Note apparent anomaly in the dates between 6 Mar and 25 April:

Some background info from various sources including Radio Waves ...

Dubbed 'Newscaster', the 11-99 was the successor to the model 11-90 ('Compact').

Model 11-90 was designed in late 1961. It is mentioned in Mingay's Price Service from Aug 1962 to Aug 1965.

Manufacture of the 11-99 began around July 1965.

Model 11-99 is mentioned in Mingay's Price Service from Feb 1966 to Feb 1975. It was mentioned in the earlier thread that the 11-99 was still seen in shops in 1975, and the Mingay's reference seems to support that.

Uses 6GV8 triode-pentode as audio amplifier. The 6GV8 was originally designed for TV as frame oscillator/sync-amp/video output.

The original 6V4 rectifier was wired as a half-wave rectifier, which simplified the power transformer secondary, needing only a single HT (non-centre-tapped) winding and a filament winding. The 11-99 featured quite low B+: only 130V for output stage and 110V for the front end..

From around late 1969 onward, the 6V4 was replaced by a silicon diode (usually BY126). The circuit schematic inside the radio was not updated to reflect this change and neither was the AORSM version.

Over its near 10 year manufacturing run, more than 40,000 model 11-99 sets were produced, at an average rate of round 330 per month (12 per day).

I just found this thread GTC. Good work. Here is my contribution:

Serial No. 20686 13 November 1969 printed on power transformer

Silicon Rectifier single diode, although the circuit diagram attached inside describes a 6V4 ---both plates tied in common.

3-wire mains cord, earthed chassis

ARTS&P label AB 772563 Cream Cabinet

Still running perfect, original paper/wax caps. I replaced filter electros three years ago. Very stable RF, no drift whatsoever.

Silicon Rectifier single diode, although the circuit diagram attached inside describes a 6V4

Many thanks BBTV. I've added yours to the list.

Your info gives us a closer idea of when the change was made from 6V4 to silicon diode. Going by our records it was somewhere between 26 Aug 1969 and 13 Nov 1969.

I omitted to say that the schematic was never changed. I've added that to post #2.