Hello,

I own a 52-unit apartment complex. About a year and a half ago, I
installed power gates. The power gates use a Multicode 300MHz
receiver, and I issue keychain remotes to all the tenants. I am having
a problem with the remotes dying. At thirteen bucks a remote, it
adds up fast.

These are very simple units, and I suspect they're mostly just
going out of alignment. Without going to the trouble of tracing the
circuit, they have:

* A one-transistor RF oscillator
* A ten-place DIP switch
* A single DIP IC - presumably a shift register to serialize the
DIP switches
* A variable capacitor - one would suppose, to tweek the freq.
* A potentiometer - to adjust the low frequency pulse oscillator?

When you press the switch, the remote emits a single squirt of
pulsed 300MHz RF.

The problem is: how to measure it? You can't just stick a counter
on it, because it's pulsed. I'm thinking to use an RF oscillator and
a mixer going to an audio amp - when the oscillator is close enough to
the remote, I'll hear it heterodyne. I don't think it needs to be
super accurate. Or maybe a scope with an XY input for lissajous
figures?

- Jerry Kaidor ( )