Farnell SB30/10? - UK Vintage Radio Repair and Restoration Discussion Forum

Uncle Bulgaria · 24th Feb 2020, 8:52 pm

Ahoy,

I have one of these I got at the Audiojumble. The current limiter appears to do nothing, and I was considering adding meters to it for ease of use.

I can find manuals for the L series, but I don't know how similar they are. The transformer is enormous and the National Express men were not happy when they insisted on helping me off with my bag despite my protestations.

"Do you know there's a weight limit?"

Thank goodness I'm slim.

evingar · 24th Feb 2020, 9:04 pm

https://rtellason.com/manuals/Farnel...owerSupply.pdf

Uncle Bulgaria · 24th Feb 2020, 9:21 pm

No sooner said...

Thank you, Chris. I was getting nothing for 'SB' in my searches so I don't know what the 'S' stands for. It appears the current limit is just that - a final overload limit not an adjustable one.

Julesomega · 1st Mar 2020, 9:12 pm

Thanks for that link, I only had a hand-drawn schematic. The guy also has several more Farnells, and a stack of other manuals which would be worth exploring.
Just in case anyone is interested what thay look like, here is the 20A version, which used to appear often on eBay, a good linear PSU for transceivers, though it would have to live under the table. A deep unit with handles, and you really need those handles.

evingar · 1st Mar 2020, 10:39 pm

Quote:

Originally Posted by Julesomega

Thanks for that link, I only had a hand-drawn schematic. The guy also has several more Farnells, and a stack of other manuals which would be worth exploring.
Just in case anyone is interested what thay look like, here is the 20A version, which used to appear often on eBay, a good linear PSU for transceivers, though it would have to live under the table. A deep unit with handles, and you really need those handles.

I used to have a 20A version - real doorstop and used to give a loud "thump" when power applied. I let it go when I got equipped with a couple of 1KW (AP1KW) Farnell Switch mode types that I plumbed in as a basic Lab +/- supply. More than slightly overkill !

duncanlowe · 2nd Mar 2020, 5:44 pm

Quote:

Originally Posted by evingar

I used to have a 20A version - real doorstop and used to give a loud "thump" when power applied. I let it go when I got equipped with a couple of 1KW (AP1KW) Farnell Switch mode types that I plumbed in as a basic Lab +/- supply. More than slightly overkill !

Yep, the thump with a vague rattle, as the side and top/bottom panels were slotted into the frame and moved with the thump from the transformer. Used them over many years at work. While I was 'away' someone has seen fit to throw them away.

The Farnell (Wayne Kerr) switch modes are fantastic. Again first came across one at work, and at least that one is still in use. On my own purchased when there were a few ex MoD ones around on eBay keeping the prices sensible, I replaced all the Rifas as they are a known issue on these. At work, in spite of a few reminders, the guy that uses it regularly, knows best. I hope I'm not there when they let go.

Uncle Bulgaria · 3rd Mar 2020, 1:50 am

Mine looks rather more rustic than yours, Julesomega! The batteries are 6V 421s for scale...

If I wanted a display, is it really as simple as plumbing in one of those V/A LCDs, or dual analogue meters? If they're arranged correctly they should show the feedback effect too.

I have been looking at flyback circuits so I could have a current limit. They seem quite simple, and there's plenty of room inside. Has anyone experience of doing this?

Julesomega · 3rd Mar 2020, 2:12 am

Farnell used type numbers very liberally so it should not be too much of a surprise to find that the SB series had both terminal block and binding post versions. The little DVM modules are wonderful, and with care you can separate the supply connection from the input connection so as to get them to work down to zero rather than to the point where they stop working. Current meter versions are available, but for 10A you really need an external shunt which are not so available

Herald1360 · 3rd Mar 2020, 11:48 am

Quote:

Originally Posted by Uncle Bulgaria

I have been looking at flyback circuits so I could have a current limit. They seem quite simple, and there's plenty of room inside. Has anyone experience of doing this?

Do you mean "foldback" perhaps? "Flyback" I would associate with a type of switching psu.

Uncle Bulgaria · 3rd Mar 2020, 11:52 am

Yes, definitely! All the Fs...

short wave · 3rd Mar 2020, 5:34 pm

Post 7 looks like an earlier one 60s? possibly using PNP output transistors (OC xx)
post 4 looks like a later one 80s using NPN output transistors (2N3055)

evingar · 3rd Mar 2020, 7:29 pm

Quote:

Originally Posted by duncanlowe

Quote:

Originally Posted by evingar

I used to have a 20A version - real doorstop and used to give a loud "thump" when power applied. I let it go when I got equipped with a couple of 1KW (AP1KW) Farnell Switch mode types that I plumbed in as a basic Lab +/- supply. More than slightly overkill !

Yep, the thump with a vague rattle, as the side and top/bottom panels were slotted into the frame and moved with the thump from the transformer. Used them over many years at work. While I was 'away' someone has seen fit to throw them away.

The Farnell (Wayne Kerr) switch modes are fantastic. Again first came across one at work, and at least that one is still in use. On my own purchased when there were a few ex MoD ones around on eBay keeping the prices sensible, I replaced all the Rifas as they are a known issue on these. At work, in spite of a few reminders, the guy that uses it regularly, knows best. I hope I'm not there when they let go.

I also have a 3KW one (AP3KW) - surplus to requirement but ebaying is problematic becuase to do shipping properly it would need palletising and crating. I doubt the average punter would swallow the charges.

All 3 of mine have had Rifa's replaced, small electrolytic caps changed and socketed devices soldered directly into the PCB's . Changing the Rifa's on the 3KW one was a right

and involved complete disassembly.

The 2 1KW jobs I think probably came from your military source judging from the stickers on them. Both worked out of the box, but one failed PAT testing due to the dodgy Rifa's - it also had an early warning "aroma" which in my experience is rare - they usually just belch out smoke without warning

24th Feb 2020, 8:52 pm	#1
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Farnell SB30/10? Ahoy, I have one of these I got at the Audiojumble. The current limiter appears to do nothing, and I was considering adding meters to it for ease of use. I can find manuals for the L series, but I don't know how similar they are. The transformer is enormous and the National Express men were not happy when they insisted on helping me off with my bag despite my protestations. "Do you know there's a weight limit?" Thank goodness I'm slim.

24th Feb 2020, 9:04 pm	#2
evingar Octode Join Date: Oct 2003 Location: Newbury, Berkshire, UK. Posts: 1,770	Re: Manual for Farnell SB30/10? https://rtellason.com/manuals/Farnel...owerSupply.pdf __________________ Chris

24th Feb 2020, 9:21 pm	#3
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Re: Manual for Farnell SB30/10? No sooner said... Thank you, Chris. I was getting nothing for 'SB' in my searches so I don't know what the 'S' stands for. It appears the current limit is just that - a final overload limit not an adjustable one.

1st Mar 2020, 9:12 pm	#4
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,102	Re: Farnell SB30/10? Thanks for that link, I only had a hand-drawn schematic. The guy also has several more Farnells, and a stack of other manuals which would be worth exploring. Just in case anyone is interested what thay look like, here is the 20A version, which used to appear often on eBay, a good linear PSU for transceivers, though it would have to live under the table. A deep unit with handles, and you really need those handles. Attached Thumbnails __________________ - Julian It's good here

3rd Mar 2020, 1:50 am	#7
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Re: Farnell SB30/10? Mine looks rather more rustic than yours, Julesomega! The batteries are 6V 421s for scale... If I wanted a display, is it really as simple as plumbing in one of those V/A LCDs, or dual analogue meters? If they're arranged correctly they should show the feedback effect too. I have been looking at flyback circuits so I could have a current limit. They seem quite simple, and there's plenty of room inside. Has anyone experience of doing this? Attached Thumbnails

3rd Mar 2020, 2:12 am	#8
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,102	Re: Farnell SB30/10? Farnell used type numbers very liberally so it should not be too much of a surprise to find that the SB series had both terminal block and binding post versions. The little DVM modules are wonderful, and with care you can separate the supply connection from the input connection so as to get them to work down to zero rather than to the point where they stop working. Current meter versions are available, but for 10A you really need an external shunt which are not so available __________________ - Julian It's good here

3rd Mar 2020, 11:52 am	#10
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Re: Farnell SB30/10? Yes, definitely! All the Fs... Last edited by Uncle Bulgaria; 3rd Mar 2020 at 12:02 pm.

3rd Mar 2020, 5:34 pm	#11
short wave Pentode Join Date: Mar 2013 Location: Leeds, West Yorkshire, UK. Posts: 246	Re: Farnell SB30/10? Post 7 looks like an earlier one 60s? possibly using PNP output transistors (OC xx) post 4 looks like a later one 80s using NPN output transistors (2N3055)