A friend that runs high power CBs fried* his 13.8V/40 A adjustable power supply and I looked at it, but did not recognize its architecture.
*suspect a detuned/failed linear amplifier backfed RF into it.

Has a massive transformer 18-0-18 VoltsAC secondary to big rectifiers, plus a switching PC-type circuitry board. NO large filter capacitors for the rectified transformer output windings. Has four NTE130 power transistors on large heat sinks.

Curious on how does it work. Any example schematics that you can point to ? Unable to find information on this MACO brand thinghy from early 90's.

 

Hi Externet,

Have you tried tracing the circuit to make a schematic?

Fortunately, illegal CB amplifiers aren't don't seem to be a disallowed topic??

 

The NTE130 transistors are 15 amp NPNs that remind me of 2N3055 with their 60v to 70v rating and gain of 20 to 70 at 4 amps. That would mean the gain at higher current is a miserable 7. They are audio speed, so don't be looking for a 50KHz switching circuit. Probably one transistor driving the other three. The heat sink for that would be worth scrap metal money!

 

A friend that runs high power CBs fried* his 13.8V/40 A adjustable power supply and I looked at it, but did not recognize its architecture.
*suspect a detuned/failed linear amplifier backfed RF into it.

Has a massive transformer 18-0-18 VoltsAC secondary to big rectifiers, plus a switching PC-type circuitry board. NO large filter capacitors for the rectified transformer output windings. Has four NTE130 power transistors on large heat sinks.

Curious on how does it work. Any example schematics that you can point to ? Unable to find information on this MACO brand thinghy from early 90's.

A suggestion:
Encourage your 'friend' to garner an amateur license

With hopeful regards
HP

 

Hi Externet,

Have you tried tracing the circuit to make a schematic?

Fortunately, illegal CB amplifiers aren't don't seem to be a disallowed topic??

1) Maybe he already has a license.
2) Nobody asked about an amplifier.

 

1) Maybe he already has a license.

Under (US) law, CB (i.e. the 11-meter citizen band) is limited to 4W RF output at the antenna jack (without regard to ERP)

So... If the 'CB' operator is outside US-FCC jurisdiction, my post may be moot...

Best regards
HP

 

Whatever CB power he may run is not my illegal thing. Am trying to learn how this thing worked, the topic is about a power supply.

Off topic: I do have my own legal 2 amateur radio operator licenses and do not care about Children's Band. And pissed at the discriminating need for a license to operate a transmitter. As everyone has one in their pocket, called cell phone with no license to use it. And those are proven faaaar more dangerous than amateur radio.

 

1) Maybe he already has a license.
2) Nobody asked about an amplifier.

1) If he had a license, he wouldn't be running a high power CB because his license could be revoked. Last time I checked, max power was 5W. But I let my FCC license expire before they started issuing lifetime licenses...
2) I read between the lines. The intent of this power supply is to run a high power CB...

 

The only thing I know about CB is that when my TV says, "Breaker breaker one nine" somebody has an illegal transmitter.

Meanwhile, let's quit hijacking this thread and talk about the power supply.

 

Off topic: I do have my own legal 2 amateur radio operator licenses and do not care about Children's Band. And pissed at the discriminating need for a license to operate a transmitter. As everyone has one in their pocket, called cell phone with no license to use it. And those are proven faaaar more dangerous than amateur radio.

People with FCC certified licenses are supposed to be qualified to maintain and operate high power (higher than 5W) transmitters. Cellphones are mW and can't cause the disruption that a KW transmitter can.

Cellphones, their users more specifically, require more laws because many users lack common sense and/or social skills... How's that for hijacking a thread?

If you hadn't mentioned the fact that it was used for a high power CB radio, we wouldn't be discussing government oversight...

 

#12 : Just made a block schematic, useless without knowledge of the 'switching' board.
Guess : unfiltered ~25 V DC is pulse-widht modulated by the 4 paralleled NTE130's whose bases are driven by the mystery board to average regulation and voltage adjusting.

 

And pissed at the discriminating need for a license to operate a transmitter.

Well... I think the idea is to prevent the Amateur bands from becoming the 'zoo' (seen on 11 meters, FRS/GMRS, etc...)

Anyway, with the repeal of the telegraphy requirement, attainment of even an Extra Class 'ticket' is now a 'snap'...

Best regards
HP

 

Are you able to power it on to troubleshoot?
Edit: take that back. You're curious how the regulator worked. Not going to happen unless you can trace the circuit or find a schematic.

 

Please trace and draw out a schematic.
Some photos would help.
I'm sure it can be repaired.

 

People with FCC certified licenses are supposed to be qualified to maintain and operate high power (higher than 5W) transmitters. Cellphones are mW and can't cause the disruption that a KW transmitter can.

Cellphones, their users more specifically, require more laws because many users lack common sense and/or social skills... How's that for hijacking a thread?

If you hadn't mentioned the fact that it was used for a high power CB radio, we wouldn't be discussing government oversight...

IMO the principal threat posed by cellular users is distracted automotive operation...

Best regards
HP

 

IMO the principal threat posed by cellular users is distracted automotive operation...

Sorry #12, but I just had to...

In my State, using a handheld cellphone while driving is illegal. But the fine (almost $500) isn't sufficient to deter infractions...

 

Am attaching a picture. The blue wires feed the 4 bases of the NTE130's
It is a filthy unit with little desire of reviving it; but curious of its workings.

IMO the principal threat posed by cellular users is distracted automotive operation...
Best regards
HP

Tell that to the ragheads. They have not discovered that you can talk instead of using them for detonations, no license needed... But we, harmless ham operators need a license.

 

#12 : Just made a block schematic, useless without knowledge of the 'switching' board.
Guess : unfiltered ~25 V DC is pulse-widht modulated by the 4 paralleled NTE130's whose bases are driven by the mystery board to average regulation and voltage adjusting.

Why are you certain of SMPS topology? -- The absence of large filters may owe to cheap design enabled by the (dubious) 'ripple immunity' inherent to many linear schemes --- One rarely sees 'PWMing' of BJTs -- 'tho being, as you said, a product of the 90's, all bets are off...

Best regards
HP

 

Why are you certain of SMPS topology? HP

My post #11 clearly says Guess. where do you get the "certain" from ?

 

I would guess "electronic capacitor" setup.