[Motorola] MOTOROLA BASE STATION POWER SUPPLIES

[Eric Lemmon]

Dan,


The TPN1110 is the more-or-less standard power supply found in a Micor
Compa-Station.  I made a quick search in my Motorola manual file, but did
not find a TPN1111 power supply.  It is easy to assume that it would be very
similar to the TPN1110 unit, but I won't make that leap without more data.

The TPN1111 might be designed to operate at a different voltage and/or
frequency.  Please advise what physical differences exist between the two
units.  Are there differences in transformers, fuses, wire colors,
connecting plugs, etc.?

It is not a good idea to connect any two power supplies in parallel, even if
they are identical, without some form of isolation between them.  A Schottky
diode module is often used for this purpose.  When two or more power
supplies are paralleled, it is more often for redundancy, not for load
sharing, and each power supply is sized to carry the entire load.  Unless
some control circuitry is added, one power supply will shoulder almost the
entire load if its output voltage is just a few millivolts higher than the
other unit.  Another reason for using a Schottky diode isolator is to
prevent a fault in one power supply from causing the other unit to trip off.
That said, it is possible for two or more power supplies to share a very
large load if they are set for the same voltage and each is equipped for
current limiting- but that feature does not exist in the typical station
power supply.

The TPN1110 power supply is intended to supply unregulated 13.8 VDC to the
power amplifier at a maximum of 25 amperes, and also provide regulated +9.6
VDC and +13.6 VDC outputs that each are fused at 4 amperes.  A ferroresonant
transformer is used to provide gross regulation to compensate for variations
in the AC input voltage.  Although this design is lauded by many as being
"bulletproof" and very reliable, it is woefully inefficient.  I ran a
comprehensive load test on a never-used TPN1110B power supply and found that
it was about 22% efficient at standby loads, and never got better than 73%
at full load of 25 amperes.  The output voltage collapsed just above 36
amperes load.  Not bad!

73, Eric Lemmon WB6FLY
 

-----Original Message-----
From: motorola-bounces at mailman.qth.net
[mailto:motorola-bounces at mailman.qth.net] On Behalf Of K0DAN
Sent: Saturday, December 01, 2007 7:49 AM
To: motorola at mailman.qth.net
Subject: [Motorola] MOTOROLA BASE STATION POWER SUPPLIES

 Hi...

 I have a TPN1110B and a TPN1111B power supply (from MICOR COMPA I think?).

 Can someone please advise differences between the two?

 Rated voltage/current output?

 Is the output sufficiently filtered that the two supplies' outputs could be

wired in parallel?

 Thanks and 73

 Dan
K0DAN



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