[Motorola] MOTOROLA BASE STATION POWER SUPPLIES

K0DAN k0dan at comcast.net
Sat Dec 1 19:13:15 EST 2007


Thanks Eric...Appreciate your very detailed reply. Between you and several 
others who responded, I have several areas to pursue. Hopefully one will 
quiet these beasts down!

BTW on the exterior, both PS's appear the same. I believe both came out of 
110W MICOR Compa's.

Does the Handbook or other source have info on building an isolator? Indeed, 
I'd like to do load sharing, not so much redundancy. I could go spend $500+ 
for a new high current switching supply, but these beasts were free!

This all started with me buying some Anderson Power Poles and deciding the 
shack should have lots of DC! Domino effect!

Tnx es 73
Dan
K0DAN

----- Original Message ----- 
From: "Eric Lemmon" <wb6fly at verizon.net>
To: "'Discussion of equipment manufactured by Motorola'" 
<motorola at mailman.qth.net>
Sent: Saturday, December 01, 2007 11:13 AM
Subject: RE: [Motorola] MOTOROLA BASE STATION POWER SUPPLIES


> 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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