Rectifier 158A - UK Vintage Radio Repair and Restoration Discussion Forum

Andy Doz · 27th Sep 2011, 2:32 pm

Can anyone identify this? I've had it in my possession for many moons. I admired it when I was in my teens, and was left it by a silent key.

It produces 13.8 Volts at 25A.

I admired it because of it's brute force engineering. There's a behemoth of a transformer, followed by two CSR's as a full wave rectifier, with appropriate control gear so the firing angle is controlled to regulate the voltage. This nasty arragement is then smoothed back into some resemblance of DC by an inductor the size of Bristol, and 66,000 uF of capacitance.

It's so heavy it bends light !

What was it's original use? I was told it was a "Post office" rectifier, and this is borne out by the plug having the old British telecom logo.

Andy Doz · 27th Sep 2011, 2:38 pm

Picture. I added the metering in the late 90's.

davegsm82 · 29th Sep 2011, 12:20 pm

At 13.8v it could be a battery charger for lead-acid's, or for running radio equipment for example that is intended to run from a vehicle's 12v electrical system.

It certainly looks like a beast, definately a change to the modern stuff - I have a 12v 50A SMPSU which measures about 6x14x30cm and is fan cooled, and won't cause temporal distortion.

I must admit, for high current stuff, I simply don't like modern SMPS's, there never seems to be enough substance to them.

Dave.

Andy Doz · 29th Sep 2011, 1:50 pm

There's a circuit diagram glued to the top, which states the output to be 28 Volts. Perhaps the previous owner modified it for 12v output to drive his rig?
Perhaps there were two versions?

I was hoping someone would come back and say , Oh yes, that's used to charge the back up battery for an XYZ123 exchange or similar...

The next problem I have is how to smuggle it into the house past SYMBO. Perhaps the temporal distortion will "cloak" it.

Pellseinydd · 29th Sep 2011, 2:44 pm

I've looked in my copy of the Vocabulary of Engineering Stores (1983) and most of the 'Rectifier 15X' range are for powering customer's equipment but the 158A is not listed.

Andy Doz · 29th Sep 2011, 3:33 pm

Thanks for the info. It does look like it was built to supply 25A all day, every day.

Pellseinydd · 29th Sep 2011, 6:07 pm

Its a baby one then!

The Rectifier 153B "Supplies power to customer's telephone apparatus in private premises, suitably smoothed whether or not a battery is connected" and it is rated at 100 amps output ! And a three phase input!

Incidentally yours is a Post Office rectifier as the P/DC XXX is the range of circuit diagrams for power equipment.

Andy Doz · 30th Sep 2011, 9:50 am

It must be said it's not too happy without a battery connected, but doesn't need much in the way. A small SLA and it is very well behaved. Drawing a dynamic load (say my 100watt SSB rig) it struggles to regulate with the current peaks being drawn without the battery.

Thank you very much for looking for me. Very much appreciated.

Herald1360 · 30th Sep 2011, 12:24 pm

Being SCR regulated with large L-C filtering, it's unlikely to have a control loop response faster than about 5Hz so an audio frequency peaky load like an SSB linear would give it a headache. The SLA is acting as an instantaneous source for current peaks thus leaving the rectifier unit to do what is was designed for- float an accumulator.

Andy Doz · 30th Sep 2011, 12:54 pm

^ you would have thought that the 66,000uF would have helped though.

davegsm82 · 30th Sep 2011, 3:45 pm

The 66mf would help with a literal instantaneous peak, but your rig pulls a significant amount of current rather than just a spike.

With battery float supplies like this, you may find that the control loop has been specifically dumbed down to prevent overloading of the power supply when you draw a large load from the supply/battery combination.

Also, something to consider is that those big caps (are they large blue Sprague ones?) may well be past their best now. I got some from the scrap yard MANY years ago that had come from the local exchange, and to be honest, they were knackered.

Dave.

John_BS · 3rd Oct 2011, 1:38 pm

Many years ago I obtained a 24v bank of "wet" Chloride Nicads (44AH) and a 24v 6A float charger. The latter uses a similar regime to regulate the voltage.

I'd say the unit was intended to float charge a large Nicad or lead-acid battery for 24v emergency lighting power or similar.

John

27th Sep 2011, 2:32 pm	#1
Andy Doz Hexode Join Date: Feb 2011 Location: Gloucestershire, UK. Posts: 376	Rectifier 158A Can anyone identify this? I've had it in my possession for many moons. I admired it when I was in my teens, and was left it by a silent key. It produces 13.8 Volts at 25A. I admired it because of it's brute force engineering. There's a behemoth of a transformer, followed by two CSR's as a full wave rectifier, with appropriate control gear so the firing angle is controlled to regulate the voltage. This nasty arragement is then smoothed back into some resemblance of DC by an inductor the size of Bristol, and 66,000 uF of capacitance. It's so heavy it bends light ! What was it's original use? I was told it was a "Post office" rectifier, and this is borne out by the plug having the old British telecom logo.

27th Sep 2011, 2:38 pm	#2
Andy Doz Hexode Join Date: Feb 2011 Location: Gloucestershire, UK. Posts: 376	Re: Rectifier 158A Picture. I added the metering in the late 90's. Attached Thumbnails Last edited by Station X; 27th Sep 2011 at 8:04 pm. Reason: Rotated image so members don't strain their necks.

29th Sep 2011, 12:20 pm	#3
davegsm82 Heptode Join Date: Jan 2004 Location: Blyth, Northumberland, UK. Posts: 858	Re: Rectifier 158A At 13.8v it could be a battery charger for lead-acid's, or for running radio equipment for example that is intended to run from a vehicle's 12v electrical system. It certainly looks like a beast, definately a change to the modern stuff - I have a 12v 50A SMPSU which measures about 6x14x30cm and is fan cooled, and won't cause temporal distortion. I must admit, for high current stuff, I simply don't like modern SMPS's, there never seems to be enough substance to them. Dave.

29th Sep 2011, 1:50 pm	#4
Andy Doz Hexode Join Date: Feb 2011 Location: Gloucestershire, UK. Posts: 376	Re: Rectifier 158A There's a circuit diagram glued to the top, which states the output to be 28 Volts. Perhaps the previous owner modified it for 12v output to drive his rig? Perhaps there were two versions? I was hoping someone would come back and say , Oh yes, that's used to charge the back up battery for an XYZ123 exchange or similar... The next problem I have is how to smuggle it into the house past SYMBO. Perhaps the temporal distortion will "cloak" it.

29th Sep 2011, 2:44 pm	#5
Pellseinydd Heptode Join Date: Jul 2007 Location: Flintshire, UK. Posts: 707	Re: Rectifier 158A I've looked in my copy of the Vocabulary of Engineering Stores (1983) and most of the 'Rectifier 15X' range are for powering customer's equipment but the 158A is not listed.

29th Sep 2011, 3:33 pm	#6
Andy Doz Hexode Join Date: Feb 2011 Location: Gloucestershire, UK. Posts: 376	Re: Rectifier 158A Thanks for the info. It does look like it was built to supply 25A all day, every day.

29th Sep 2011, 6:07 pm	#7
Pellseinydd Heptode Join Date: Jul 2007 Location: Flintshire, UK. Posts: 707	Re: Rectifier 158A Its a baby one then! The Rectifier 153B "Supplies power to customer's telephone apparatus in private premises, suitably smoothed whether or not a battery is connected" and it is rated at 100 amps output ! And a three phase input! Incidentally yours is a Post Office rectifier as the P/DC XXX is the range of circuit diagrams for power equipment.

30th Sep 2011, 9:50 am	#8
Andy Doz Hexode Join Date: Feb 2011 Location: Gloucestershire, UK. Posts: 376	Re: Rectifier 158A It must be said it's not too happy without a battery connected, but doesn't need much in the way. A small SLA and it is very well behaved. Drawing a dynamic load (say my 100watt SSB rig) it struggles to regulate with the current peaks being drawn without the battery. Thank you very much for looking for me. Very much appreciated.

30th Sep 2011, 12:24 pm	#9
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Rectifier 158A Being SCR regulated with large L-C filtering, it's unlikely to have a control loop response faster than about 5Hz so an audio frequency peaky load like an SSB linear would give it a headache. The SLA is acting as an instantaneous source for current peaks thus leaving the rectifier unit to do what is was designed for- float an accumulator. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

30th Sep 2011, 12:54 pm	#10
Andy Doz Hexode Join Date: Feb 2011 Location: Gloucestershire, UK. Posts: 376	Re: Rectifier 158A ^ you would have thought that the 66,000uF would have helped though.

30th Sep 2011, 3:45 pm	#11
davegsm82 Heptode Join Date: Jan 2004 Location: Blyth, Northumberland, UK. Posts: 858	Re: Rectifier 158A The 66mf would help with a literal instantaneous peak, but your rig pulls a significant amount of current rather than just a spike. With battery float supplies like this, you may find that the control loop has been specifically dumbed down to prevent overloading of the power supply when you draw a large load from the supply/battery combination. Also, something to consider is that those big caps (are they large blue Sprague ones?) may well be past their best now. I got some from the scrap yard MANY years ago that had come from the local exchange, and to be honest, they were knackered. Dave.

3rd Oct 2011, 1:38 pm	#12
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,782	Re: Rectifier 158A Many years ago I obtained a 24v bank of "wet" Chloride Nicads (44AH) and a 24v 6A float charger. The latter uses a similar regime to regulate the voltage. I'd say the unit was intended to float charge a large Nicad or lead-acid battery for 24v emergency lighting power or similar. John