[Kenwood] TM-V71A Narrowband FM

[wb4eel]

The TM-V71A has a narrowband capability, but little info in the user's
manual. MARS is starting to require VHF operations to be narrowband with
specific performance requirements.

NFM is selected in menu 102 for the VFO and then can be stored in a memory
channel.

With some quick testing: the NWS broadcast gets louder in NFM than in FM,
but there is no distortion. I was unable to determine if the transmitted
audio is softer in NFM. It does not seem to make much difference with DTMF
tones which may be set to low deviation anyway.

Does the NFM capability just adjust the discriminator and the deviation
settings or does it actually change the transmit and receive IF bandwidths?
The old Motorola tube receivers had a new narrowband IF filter when they
changed to 30 kHz channel spacing back in the 60's.

John W. Louth
WB4EEL