[ARC5] U.S. Military Aircraft VHF-AM Set Crystal Frequencies

[Mike Morrow]

Operating Frequency vs. Crystal Frequency for common WW2-era
VHF-AM Command Sets.  ALL frequencies below are MHz.
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A.  U.S. NAVY - WW2-Era Aircraft VHF-AM Command Sets
           (Operating frequencies shown are known to
           have been supplied from factory in some sets.)

1.  RT-18*/ARC-1
                Operating      Crystal
Channel         Freq           Freq
  1             116.1          5.91
  2             124.38         6.37
  3             126.18         6.47
  4             128.7          6.61
  5             142.02         7.35
  6             142.56         7.38
  7             142.74         7.39
  8             144.36         7.48
  9             146.16         7.58
  GC            140.58         7.27

Operating Freq:  100 to 156
Crystal Type:  CR-1A/AR
Operating Freq = Crystal Freq x 18 + 9.72
Crystal Freq = (Operating Freq - 9.72) / 18

2.  RT-19/ARC-4
               Operating      R Crystal      T Crystal
Channel        Freq           Freq           Freq
 1 P-P         140.58         8.16125        5.8575
 2 P-G         142.02         8.25125        5.9175
 3 P-G         142.46         8.285          5.94
 4 P-G         142.74         8.29625        5.9475

Operating Freq:  140 to 144
Crystal Type:  WECo Type 703A (Dual Crystal Unit)
R Freq = R Crystal Freq x 16 + 10
R Crystal Freq = (R Freq - 10) / 16
T Freq = T Crystal Freq x 24
T Crystal Freq = T Freq / 24

3.  AN/ARC-5                  R-28           T-23
                Operating     R Crystal      T Crystal
Channel         Freq          Freq           Freq
  A             116.1         4.55           6.45
  B             126.18        4.97           7.01
  C             140.58        5.57           7.81
  D             142.74        5.66           7.93

                              R-28           T-126
                Operating     R Crystal      T Crystal
Channel         Freq          Freq           Freq
  A             111.78        4.55           6.21
  B             116.46        5.57           6.47
  C             126.18        4.97           7.01
  D             137.88        5.66           7.66

Operating Freq:  100 to 156 (T-23); 100 to 146 (T-126)
Crystal Type:  Receiver DC-31; Transmitter CR-1A/AR (DC-30)
R Freq = R Crystal Freq x 24 + 6.9
R Crystal Freq = (R Freq - 6.9) / 24
T Freq = T Crystal Freq x 18
T Crystal Freq = T Freq / 18

Transmitter Channel Frequency Bands:
Channel        T-23/ARC-5          T-126/ARC-5
  A            100 to 124          100 to 124
  B            122 to 146          100 to 124
  C            122 to 146          100 to 124
  D            132 to 156          122 to 146

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B.  U.S. ARMY - WW2-Era Aircraft VHF-AM Command Sets

1.  SCR-522-A               R: BC-624-*     T: BC-625-*
Channels:  A, B, C, D

2.  AN/ARC-3*               R-77*           T-67*
Channels:  A, B, C, D, E, F, G, H

Details below are applicable to both SCR-522-A and AN/ARC-3*:
Operating Frequency:  100 to 156
Crystal Type:  DC-30 (CR-1A/AR)
R Freq = R Crystal Freq x H + 12
R Crystal Freq = (R Freq - 12) / H
H = Local Oscillator Harmonic
    Operating Freq      H
    100 to 108          11
    108 to 116          12
    116 to 124          13
    124 to 132          14
    132 to 140          15
    140 to 148          16
    148 to 156          17
T Freq = T Crystal Freq x 18
T Crystal Freq = T Freq / 18
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Mike / KK5F