902/903 OPERATION, SOME THOUGHTS

This is a band that is shared with a lot of portable telephones, wireless home speaker systems, security systems and a host of other unlicensed Part 15 devices. As hams we are pretty much stuck with any interference that we receive.  Although Part 15 of the FCC rules make interference resolution the problem of the unlicensed source, in practical terms how do you get a portable phone manufacturer to solve an interference problem from your next door neighbor. So the bottom line is - we are stuck with what we get.

Because of regional differences, and the transverter equipment people have, some areas concentrate operation around 902 while other regions use 903. A transverter designed for 903 with a 144 MHz IF will not work at 902. Down East Microwave has one solution where they offer a dual crystal transverter so you can operate on 902 or 903 simply by switching crystals. Of course you can order the transverter for either 902 or 903. But I have a better idea that will work for some of you.

What I did to get around this problem is order a 903 transverter and use my IC-821H 144/432 Icom transceiver as the IF radio. Now the 821, like many radios, has broader receive capability then it does transmit. However, there are modifications you can make to expand the transmit range. This is what I did. Now if I need to work 902 I simply run the 821 down to 143 MHz and there I am on 902. This is perfectly legal providing you DO NOT emit a signal on 143 MHz that might interfere with another licensed service. Providing you meet FCC regulations as to sprurious emissions (and the local oscillator and the IF signal are spurious signals) then you are OK. Just make certain that you never ever transmit a signal on 143!

You could go the other way and get a 902 transverter but then to operate at 903 your IF radio would need to be at 145 MHz. This gets you into a potential conflict with local repeaters and/or simplex frequencies that can bleed through to you IF radio and interfere with 903 operation.

Check QRZ.com for radio modifications and see what they have. Just be really careful to follow the directions. If you remove the wrong part, your radio may be useless and need factory service. Another caution, unsolder the parts to be removed with a CMOS rated soldering iron and a very small tip. Get yourself a good magnifying glass since all modern day radios use surface mount devices and they are REALLY tiny. We don't want you destroying your radio and having to spend money to get it repaired.

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