mains transformer info needed please - UK Vintage Radio Repair and Restoration Discussion Forum

newtube · 22nd Mar 2009, 9:40 pm

Hi guys, i need to find a mains transformer to power these output transformers, it can be new or vintage. . .

http://i20.photobucket.com/albums/b2...nce300BOPT.jpg

This is a wee schematic of them
http://i20.photobucket.com/albums/b2...TSchematic.jpg

They were removed from a consonant 300b set and the only info i have on them is they have a single primary winding, 2k5 -3k5 and are 60-70ma.

I will be using them to build a simple se stereo amp with 6l6gc valves.

Can you help me out with ideas fella's, and don't get too tecnical, i'm new to this!
Regards,
Darran.

Ed_Dinning · 23rd Mar 2009, 9:21 pm

Hi Darran, your average radio or even radiogram mains tranny would struggle with that lot.
You will probabaly want a mains primary; with 350-0-350 at 150mA, a 5 or 6.3V rectifier heater winding at about 3A, depending on the rectifier valve chosen; then 6.3V, ideally centre tapped at about 6A for the 2 sets of 6L6's (this could be 2, 6.3's at 3A). If you are going for voltage bias rather than cathode bias you will then need an additional 30V winding at 10mA or so.
See what you can find as surplus (as far back as ww2) or consider using more than one transformer. You could get one wound with various windings and taps on it to experiment with, but that would be expensive.

Ed

newtube · 27th Mar 2009, 9:12 pm

Thanks for that ED, what do you think to this one-
PRIMARY VOLTAGE IS..........0 / 200-215 / 220 - 230 / 240 - 250. WITH SELECTOR PLATE. SECONDARY VOLTAGES.... 380 - 0 - 380 @ 100mA, 5.0 @ 2.0A, FOR RECTIFIER. 6.3 @ 3A, ( X 2 SETS )
THE RECTIFIER SOCKET IS STILL CONNECTED READY FOR A GZ34 OR SIMILAR VALVE. (the one i'm using)
THIS TRANSFORMER IS MADE BY HINCHLEY.

thanks again,
Darran.

Ed_Dinning · 28th Mar 2009, 10:02 pm

Darran, it's big but probably not up to running your stero amp at full whack for long.

If you post the circuit I'll se what you need. The GZ34is good for 160mA. But the will give an HT "wattage" of about 45 continious in terms of DC power to the valves. In rough figures (experts please correct me) this equates to a music power of about 6 tp 8 watts/ channel max. If you can get a second tranny, Great.

Ed

Mr Moose · 29th Mar 2009, 1:03 am

Hello,
According to my valve manual the two 6L6s would require about 120-140ma HT current so as Ed says you really need at least a 150ma transformer. The transformer you suggest is only 100ma. (You could possibly increase the grid (or cathode) bias to reduce the anode current but this would reduce the power output)
You could consider the following transformers, The VT 424 has a single HT winding and no rectifier heater winding so you would have to use silicon rectifiers instead of a valve but it is much cheaper than the other two which will work with a valve rectifier. According to the specifications they all have an output of 200ma or more.
http://livinginthepast-audioweb.co.uk/xfrmrvt424.php
http://livinginthepast-audioweb.co.uk/xfrmrvt1037.php
http://livinginthepast-audioweb.co.uk/xfrmrvt1039.php
I think you have to add £6.00 to the prices for postage.
Yours, Richard

newtube · 29th Mar 2009, 11:09 am

Thats a great site mr moose!
I'll have a good look at their transformers later and report back. . .

Thanks.

22nd Mar 2009, 9:40 pm	#1
newtube Triode Join Date: Mar 2009 Location: SHEFFIELD Posts: 38	mains transformer info needed please Hi guys, i need to find a mains transformer to power these output transformers, it can be new or vintage. . . http://i20.photobucket.com/albums/b2...nce300BOPT.jpg This is a wee schematic of them http://i20.photobucket.com/albums/b2...TSchematic.jpg They were removed from a consonant 300b set and the only info i have on them is they have a single primary winding, 2k5 -3k5 and are 60-70ma. I will be using them to build a simple se stereo amp with 6l6gc valves. Can you help me out with ideas fella's, and don't get too tecnical, i'm new to this! Regards, Darran.

23rd Mar 2009, 9:21 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: mains transformer info needed please Hi Darran, your average radio or even radiogram mains tranny would struggle with that lot. You will probabaly want a mains primary; with 350-0-350 at 150mA, a 5 or 6.3V rectifier heater winding at about 3A, depending on the rectifier valve chosen; then 6.3V, ideally centre tapped at about 6A for the 2 sets of 6L6's (this could be 2, 6.3's at 3A). If you are going for voltage bias rather than cathode bias you will then need an additional 30V winding at 10mA or so. See what you can find as surplus (as far back as ww2) or consider using more than one transformer. You could get one wound with various windings and taps on it to experiment with, but that would be expensive. Ed

27th Mar 2009, 9:12 pm	#3
newtube Triode Join Date: Mar 2009 Location: SHEFFIELD Posts: 38	Re: mains transformer info needed please Thanks for that ED, what do you think to this one- PRIMARY VOLTAGE IS..........0 / 200-215 / 220 - 230 / 240 - 250. WITH SELECTOR PLATE. SECONDARY VOLTAGES.... 380 - 0 - 380 @ 100mA, 5.0 @ 2.0A, FOR RECTIFIER. 6.3 @ 3A, ( X 2 SETS ) THE RECTIFIER SOCKET IS STILL CONNECTED READY FOR A GZ34 OR SIMILAR VALVE. (the one i'm using) THIS TRANSFORMER IS MADE BY HINCHLEY. thanks again, Darran.

28th Mar 2009, 10:02 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: mains transformer info needed please Darran, it's big but probably not up to running your stero amp at full whack for long. If you post the circuit I'll se what you need. The GZ34is good for 160mA. But the will give an HT "wattage" of about 45 continious in terms of DC power to the valves. In rough figures (experts please correct me) this equates to a music power of about 6 tp 8 watts/ channel max. If you can get a second tranny, Great. Ed

29th Mar 2009, 1:03 am	#5
Mr Moose Octode Join Date: Jul 2008 Location: Gloucestershire, UK. Posts: 1,043	Re: mains transformer info needed please Hello, According to my valve manual the two 6L6s would require about 120-140ma HT current so as Ed says you really need at least a 150ma transformer. The transformer you suggest is only 100ma. (You could possibly increase the grid (or cathode) bias to reduce the anode current but this would reduce the power output) You could consider the following transformers, The VT 424 has a single HT winding and no rectifier heater winding so you would have to use silicon rectifiers instead of a valve but it is much cheaper than the other two which will work with a valve rectifier. According to the specifications they all have an output of 200ma or more. http://livinginthepast-audioweb.co.uk/xfrmrvt424.php http://livinginthepast-audioweb.co.uk/xfrmrvt1037.php http://livinginthepast-audioweb.co.uk/xfrmrvt1039.php I think you have to add £6.00 to the prices for postage. Yours, Richard Last edited by Mr Moose; 29th Mar 2009 at 1:28 am.

29th Mar 2009, 11:09 am	#6
newtube Triode Join Date: Mar 2009 Location: SHEFFIELD Posts: 38	Re: mains transformer info needed please Thats a great site mr moose! I'll have a good look at their transformers later and report back. . . Thanks.