[ARC5] WWII-Era VHF Command Set Frequencies and Crystal Information
Kenneth G. Gordon
kgordon2006 at frontier.com
Thu Nov 17 17:33:26 EST 2011
Very interesting, Mike.
However, I thought the GC (Guard Channel) frequency was always set to
121.5 MHz, the emergency frequency.
At least the ARC-1 I got from AFMARS back in the 1960s had that
installed there...
Ken W7EKB
On 17 Nov 2011 at 0:00, Mike Morrow wrote:
> U.S. Navy - Operating Frequencies Supplied In New Sets
>
> Receiver Transmitter
> Channel Freq. (MHz) Crystal Freq. (kHz)
>
> AN/ARC-1 RT-18/ARC-1
> 1 116.10 5910.00
> 2 124.38 6370.00
> 3 126.18 6470.00
> 4 128.70 6610.00
> 5 142.02 7350.00
> 6 142.56 7380.00
> 7 142.74 7390.00
> 8 144.36 7480.00
> 9 146.16 7580.00
> GC 140.58 7270.00
> Equipment Operating Frequency Range: 100 to 156 MHz
> Crystal Type: CR-1A/AR
> Operating Frequency MHz = Crystal Frequency kHz x 18 / 1000 + 9.72
>
>
> AN/ARC-4 RT-19/ARC-4
> 1 P-P 140.58 8161.25 5857.50
> 2 P-G 142.02 8251.25 5917.50
> 3 P-G 142.46 8285.00 5940.00
> 4 P-G 142.74 8296.25 5947.50
> Equipment Operating Frequency Range: 140 to 144 MHz
> Crystal Type: WECo Type 703A (Dual Crystal Unit)
> Receiver Frequency MHz = Crystal Frequency kHz x 16 / 1000 + 10
> Transmitter Frequency MHz = Crystal Frequency kHz x 24 / 1000
>
>
> AN/ARC-5 R-28/ARC-5 T-23/ARC-5
> A 116.10 4550.00 6450.00
> B 126.18 4970.00 7010.00
> C 140.58 5570.00 7810.00
> D 142.74 5660.00 7930.00
> Equipment Operating Frequency Range: 100 to 156 MHz
> Crystal Type: Receiver - DC-31 Transmitter - CR-1A/AR (DC-30)
> Receiver Frequency MHz = Crystal Frequency kHz x 24 / 1000 + 6.9
> Transmitter Frequency MHz = Crystal Frequency kHz x 18 / 1000
> Transmitter Channel Allowable Frequency Ranges
> 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
>
>
> U.S. Army - Operating Frequencies Supplied In New Sets
>
> Receiver Transmitter
> Channel Freq. (MHz) Crystal Freq. (kHz)
>
> SCR-522-A BC-624-* BC-625-*
> A Unknown
> B Unknown
> C Unknown
> D Unknown
> Equipment Operating Frequency Range: 100 to 156 MHz
> Crystal Type: CR-1A/AR
> Receiver Frequency MHz = Crystal Frequency kHz x H / 1000 + 12
> Receiver Frequency H (Local Oscillator Harmonic)
> 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
> Transmitter Frequency MHz = Crystal Frequency kHz x 18 / 1000
>
> AN/ARC-3 R-77*/ARC-5 T-67*/ARC-5
> A Unknown
> B Unknown
> C Unknown
> D Unknown
> E Unknown
> F Unknown
> G Unknown
> H Unknown
> Equipment Operating Frequency Range: 100 to 156 MHz
> Crystal Type: CR-1A/AR
> Receiver Frequency MHz = Crystal Frequency kHz x H / 1000 + 12
> Receiver Frequency H (Local Oscillator Harmonic)
> 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
> Transmitter Frequency MHz = Crystal Frequency kHz x 18 / 1000
>
> Comment: This is a gratuitous posting to summarize the crystal versus
> operating frequency relationships of all the common U.S. military
> aircraft VHF sets of the WWII era.
>
> Also listed are the frequencies supplied with new equipment for U.S.
> Navy sets. I only recently determined the AN/ARC-1 supplied
> frequencies after I examined a NOS AN/ARC-1 (yes, it still has the
> rare auto-tune setting dial tuning device) that has an early WWII
> contract number and all identical-make crystals for the early VHF-AM
> frequencies used by the military in WWII. I think this set may
> somehow have escaped use because the nomenclature decal that
> Westinghouse applied to it says C-45/ARC-1 rather than the correct
> RT-18/ARC-1. Sometimes simple errors like that can alter a set's
> usage, causing it to be withheld from issue or use.
>
> I don't have enough information on new USAAF VHF sets (except the
> 48-channel version of the AN/ARC-3 known as the AN/ARC-49) to know for
> sure if they came from the factory with crystals for some standard
> channels already installed. (The AN/ARC-49 did.) I'd like to hear
> from anyone who has such information. The USAAF continued use of VHF
> command sets long after WWII (while the USN quickly abandoned VHF in
> favor of UHF), so there is little chance that an SCR-522-A or AN/ARC-3
> found today with all military-use crystals still installed would
> reflect what was there when the unit left the factory.
>
> Looking at the various formulas relating crystal frequency to
> operating frequency, and also crystal types, one finds little
> consistency between the USN's AN/ARC-1, -4, and -5 VHF sets. The
> USAAF sets, however, used exactly the same relationships and crystal
> types for the SCR-522-A and the AN/ARC-3.
>
> Mike / KK5F
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