While adjusting the depth of modulation in AM mode, I noticed an undesirable effect.

Without modulation the carrier would be at some arbitrary level on the scope.

When I spoke into the mike, I would observe the modulation as normal.

But what I noticed unusual was that the unmodulated carrier level would rise slowly back to it?s pre-modulation level. With modulation it would dip down and rise slowly taking about a second or two to recover. This is not ?normal? AM modulation.

The built-in PO meter agreed with the scope as well as an external wattmeter.

It seemed like the ALC was causing the output to compress and then recover to normal.

This 735 mod involves ?stiffening? up the ALC when in AM mode.

Tools required:

Soldering iron with fine point

Magnifying glass.

Parts required:

One 2N2222 transistor

One 100k ohm watt resistor.

One 10 Ohm watt resistor.

I believe that a watt should suffice. I didn?t have one handy at the time.

Pictures of the mod:

Picture 1 W16 location

Picture 2 W22 location

Good luck and feel free to contact me with any questions you might have concerning this mod. You may e-mail me via www.eqsl.net. Sign in and do a call search on AA3M.


John AA3M