[Motorola] P23AAM Help needed

[Geoff Fors]

Jack,

I will look through my library when I get home and see what I have.

The AAM series portable uses a different receiver than the BAM.  The BAM has 
an all solid state receiver while the AAM uses two subminiature wire-lead 
tubes in the IF stage.  As a result, the power supplies are completely 
different and as I recall, the wiring harnesses and the connectors are as 
well.

All transistors should be PNP Germanium.  At that time that was the 
standard.

Because of the differences, a BAM manual will be more or less hopeless as 
far as helping you with the earlier AAM series.

The audio section PC boards on these usually have a few tantalum slug 
capacitors that by now have eaten their leads off or are growing flowers out 
the ends, or both.  Most of the tubular electrolytics are probably dried up 
throughout the set and a quick trip through it with an ESR meter will find 
which ones have.

I have found on my BAM's that five D style NiCads in a plastic holder for 
six will fit where the original NiCad battery went.  You have to short 
across the empty cell holder on a six battery setup.  For some reason if you 
try to use six batteries the receiver becomes unstable above 7V and goes 
into oscillation and/or other strange behavior.

To further muddy the water, in 1962-64 Motorola started selling field 
retrofit kits to convert the AAM series radios into BAM series with solid 
state receivers, through conversion kits.  Among other things the kits 
included a new receiver board and some power supply modification kits, and 
those had a sticker which looked like the symbol for a transistor that you 
applied to the side of the radio.  I saw some depot overhauled and upgraded 
radios that had the transistor symbol screened in paint on the sides.

Note that the power supply is a DC-DC converter that runs all the time and 
powers the receiver as well as the transmitter, so that even though the set 
is technically positive ground, it is being powered by the secondary of the 
power transformer and thus unrelated to the vehicle ground when you use the 
12 Volt adapter cable that plugs in where that little door is.

A 1956 manual would be the first one as the radio wasn't even introduced to 
the market until 1957.

For various reasons the AAM series are always in need of a lot of work when 
I get them, while the BAM's seem to always fire right up as they are.

By the way, the cost of crystals today is outrageous.  Typically $ 25 - 35 
each.

Geoff
WB6NVH
Monterey CA