USAF McClellan AFB, CA :
here a recording of a voice mirror (yakker) from 1974 (Dan Greenall)
and in 1974 Dan Greenall added this card to his collection
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Callsigns:
AFI
AFI2
MCC
Frequencies Voice:
3067
3087
3134
3137
4724
4725
4727
4745
4746
5708
6712
6727
6730
6738
6739
6760
6780
7632
7997
8050
8967
8968
8986
8989
8992
9013
9014
9016
9017
9020
9025
9057
9320
10112
11035
11156
11175
11176
11181
11182
11220
11226
11239
11243
11244
11246
11249
11413
13200
13201
13209
13210
13211
13215
13242
13247
13248
15015
15016
15031
15032
15043
15048
17440
17975
17976
17993
18002
18003
18060
18290
20124
20631
24274
Frequencies Radioteletype:
5708
6715
9025
11182.8
13215
15043
18003
20631
Systems used:
75 Bd
ALE MIL188-141