National Interagency Incident Communications Division

March 19, 2012

To: Radio Users

From: Stephen M. Jenkins, Chief, National Interagency Incident 

Communications

Subject: Federal Communications Commission Frequency Narrowbanding 

Incompatibility

The Federal Communications Commission (FCC) has begun issuing narrowband 

VHF-FM frequencies to states, local governments, and private organizations on 

which some federal land management agency VHF-FM radios cannot operate. 

This may prohibit federal land management agencies from communicating on 

these frequencies.

Background

The FCC began transitioning from 15 kHz (wideband) to 7.5 kHz (narrowband) 

channel spacing in 2005 for the 150 to 174 MHz frequency band. 

The FCC-controlled 150 to 174 MHz frequency band is used by states, local 

governments, and private organizations in the same manner as the federallycontrolled 162 to 174 MHz frequency band. FCC’s narrowbanding plan (15 kHz 

to 7.5 kHz channel spacing) is separate from the largely-completed federal 

narrowbanding plan (25 kHz to 12.5 kHz channel spacing). The federal 

narrowbanding plan is controlled by the National Telecommunications and 

Information Administration (NTIA). The FCC manages frequency use for states, 

local governments, and private organizations while the NTIA manages frequencies 

for federal users. NTIA’s narrowbanding plan was completed in 2005, while the 

FCC plan began in 2005 and is expected to be completed for public safety users on 

January 1, 2013.

This issue first manifested itself on the Sweat Farm Road fire in Georgia where a 

local 7.5 kHz-type frequency was being used. The fire could not use NIFC fire 

cache-assigned B/K EPH radios because B/K EPH radios would not operate on 

these newly-issued 7.5 kHz-spaced frequencies. The fire was immediately sent 

B/K DPH replacement radios. When the Oregon Department of Forestry activated 
several new mountain repeater sites utilizing recently-issued 7.5-kHz spaced

channels, the same problem occurred with locally-owned USFS radios. As the 

FCC may be issuing 7.5 kHz-spaced channels in the future, incompatibility issues 

with existing federal radios will only increase.

Symptoms of Incompatibility

Any radio experiencing 7.5 kHz channel spacing incompatibility will not be able to 

have the new 7.5 kHz-spaced frequencies programmed into them. There are many 

new FCC frequencies resulting from this channel spacing plan. Three of the new 

7.5 kHz-type frequencies are 151.1525, 158.7825, and 159.2925. Users should 

attempt to program any of these three frequencies into a radio to determine 7.5 kHz 

compatibility. A quick radio test will confirm whether the radio successfully 

operates.

Affected Equipment

Radios designed before 1997 will probably be 7.5 kHz-incompatible. Radios 

manufactured after 1997, using a pre-1997 design, will also likely be incompatible. 

However, radios designed since 1997 should be 7.5 kHz-compatible. Of primary 

concern are B/K EPH model radios. The B/K EPH radio is widely used by federal 

land management agencies and is not 7.5 kHz-channel-compatible. Take note that 

it is a radio’s design date and not the radio’s manufacture date which is important. 

NIFC’s fire cache has several B/K EPH radios built and purchased in 2002 which 

are 7.5 kHz-incompatible.

The following radios are known to be 7.5 kHz-incompatible:

• B/K models: LPH and EPH

• Eureka Radio: ERS96000

• Northern Airborne Technologies (NAT): NPX138

• Wulfsberg Electronics: 9600

The following radios are known to be 7.5 kHz-compatible.

• B/K models: GPH, DPH, and KNG-P150

• Cobham: NPX136D

• Datron: Guardian

• EF Johnson: 5113, 5123, and 5133

• Midland: STP105B

• Motorola: XTS2500 and XTS5000

• NAT: NTX138
• Technisonic Industries: TFM-138B, TDFM-136, TDFM-136A, and TDFM136/NV

• Thales (Racal): P25

Note: Some individuals are able to program a NAT NPX138’s display to show 7.5 

kHz-channel-spacing operation. NAT is aware of this and has said while the 

display shows 7.5 kHz operation the radio will continue to operate on the nearest 

non-7.5 kHz frequency. NAT disavows this work-around and reiterates that the 

NPX138 is not 7.5 kHz-channel-capable.

Correction of Problem

Local communications personnel should determine if their state and/or local 

governments have recently been issued VHF-FM 7.5 kHz frequencies from the 

FCC. This information must be provided to dispatch centers so appropriate action 

can be taken. Resources responding to an area (where the use of 7.5 kHz-spaced 

channels plays an important role in a local communications plan) must be informed 

of any radio limitations prior to the resource’s arrival.

Interagency fire aviation resources have already dealt with this issue by converting

to P25 digital radios. All P25 digital radios (aviation, mobile, and portable) are 7.5 

kHz-channel-spacing compatible. Ground resources will have to transition to 

newer 7.5 kHz-compatible radios as conditions and funding permit.

Questions concerning radios on this list can be directed to: Bob Dukart (208-387-

5852) bdukart@blm.gov.

/s/ STEPHEN M. JENKINS

Chief, NIICD/NIFC