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gunafficionado
11-02-2011, 8:48 AM
Will modifying a radio for MARS/CAP affect Rx sensitivity? The radio is a Yaesu FT270 HT.

DVSmith
11-02-2011, 9:38 AM
I could not find a schematic online that didn't require some sort of payment or membership, but from reading the mod, it seems you are just changing the programming. The transmitter may not be perfectly tuned for the new frequency range, but I don't think it will have any effect on the receiver.

mej16489
11-02-2011, 9:50 AM
Will modifying a radio for MARS/CAP affect Rx sensitivity? The radio is a Yaesu FT270 HT.

On modern radios, a MARS/CAP mod is typically only change what frequencies the transceiver will allow you to transmit upon. There would typically be no effect on receive sensitivity.

However - it is theoretically possible that transmitting out of band can have a negative effect upon receiver stages for other bands - but generally, this wouldn't ever happen on actual MARS/CAP frequencies.

The most 'at risk' aspect of a MARS/CAP mod is actually the transmitter final amplifier. If you stay on MARS/CAP frequencies you will generally be safe.

Markinsac
11-03-2011, 4:02 AM
There have been many changes to regulations regarding radios since the FT270 came out.

You can't use modified radios any longer. The radio has to be a commercial radio, narrowband certified, and on the "accepted" list for CAP.

You're better off finding a compatible radio just for CAP use. The rules are tighter, and you don't want to be caught using a wrong radio out there any longer.