[Hallicrafters] Determining age of SX-71 ??

[Deane McIntyre]

Phil Atchley wrote:
> 

> 
> Also, I thought tubes back then were "date coded" much as modern parts are.
> This set has a number of what I presume must be "original" Hallicrafters
> tubes, but the numbers don't appear to really mean anything.
> 
> 6SK7  3-04,   188-5
> 6SH7  2-48,   274
> 6SK7  3-04,   188-5
> 6H6    2-39,   274
> 6AL5  33  10  29
> 
> 73 de Phil  KO6BB
>
2-48 = 48th week of 1952
3-04 = 4th week of 1953
2-39 = 39th week of 1952

Later date codes used the last two digits of the year,
for example 61-16 would be 16th week of 1961. My SX-110 for example
still has all of the orginal Halli tunes, all with 1961 date
codes.

Note sure arout the 6AL5 code.

The other numbers code for the manufacturer of the tube
-188 = GE and 274 = RCA.

73, Deane McIntyre VE6BPO
dmcintyr at ucalgary.ca