When the FCC (AKA Motorola) mandated narrow band for Part 95 services, they forgot that a small number of VHF channels, primarily VHF mutual aid channels required 2.5 KHz resolution.
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Because manufacturers could continue to sell older model radios for a time, there are exceptions in that some VHF radio equipment may not properly resolve certain channels, which require the radio to resolve to 2.5 KHz channel steps.
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(From my website:)
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Examples are
VCALL -10 155.7525 MHz,
VTAC - 12? 154.4525 MHz and
VTAC - 14? 159.4725 MHz
These channels cannot be evenly divided by radio synthesizers, which do not resolve to 2.5 KHz.
Additionally, there are other VHF channels on these "7.5 KHz channel centers" which may be
troublesome.
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I think you will soon realize that a lot of commercial VHF radios sold decades ago will be incompatible with your channel center.
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The Real RFI-EMI-GUY
RFI-EMI-GUY