Good to see you think alike, ill do that tomorrow and see, i'll write down measurements as i go along
Yep, from Primary Windings U.K. https://primarywindings.com/product/mains-transformer-mullard-5-10-stereo/
Mains transformer – 600V @ 200mA C.T., 6.3V @ 4A and 6.3V/5V @ 2A
And a Sovtek 5AR4 too
I'm trying to simulate the B+ you are going to get under load using PSUD2 utility. Do you have the DCR values for the power transformer and the choke? I did not see the values on the site.
Hoorah!
First checks done.
No valves inserted as a precaution.
Mains supply is this morning as high as 246 and not 240!
Checked 6.3VAC, it was at 6.8, bad news....
Checked 5VAC, it was at 5.6, again bad news.
Checked the 300-0-300 and as can be expected it was too high, actually being close to 325-0-325.
I'll now rewire the mains transformer not to 240VAC but use the tap +10 being 250VAC
First checks done.
No valves inserted as a precaution.
Mains supply is this morning as high as 246 and not 240!
Checked 6.3VAC, it was at 6.8, bad news....
Checked 5VAC, it was at 5.6, again bad news.
Checked the 300-0-300 and as can be expected it was too high, actually being close to 325-0-325.
I'll now rewire the mains transformer not to 240VAC but use the tap +10 being 250VAC
True it's unloaded, but i've already rewired the mains input using the +10% being 250.
I'd rather be safe than sorry.
Hope to continue a bit later
Ok, i've now got the Mains Tx wired to 250VAC.
And with the light bulb wired in series with the live (brown) cable i have these voltages.
T1-RED-1 }
T1-RED-3 } 490VAC
T1-GRN-1}
T1-GRN-2} 5.1VAC
T1-YEL-1}
T1-YEL-2} 4.2VAC
Might now insert the valve rectifier Sovtek 5AR4 and check what D.C. output i get.
Depending how things continue, i might revert back to 240 and check voltages again, agreeing with JCAlvarez there is no load.
And with the light bulb wired in series with the live (brown) cable i have these voltages.
T1-RED-1 }
T1-RED-3 } 490VAC
T1-GRN-1}
T1-GRN-2} 5.1VAC
T1-YEL-1}
T1-YEL-2} 4.2VAC
Might now insert the valve rectifier Sovtek 5AR4 and check what D.C. output i get.
Depending how things continue, i might revert back to 240 and check voltages again, agreeing with JCAlvarez there is no load.
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It is a leap of faith!
Remember this is a proven design, built in the hundreds. The issues you are being cautious about are construction issues, most likely the wiring of the peripherals. Those are best tested by reverse engineering what you have constructed and comparing with what you intended.
It is nice to build the same way as a lighthouse. Once on land, then dismantle and build again in the sea.
Remember this is a proven design, built in the hundreds. The issues you are being cautious about are construction issues, most likely the wiring of the peripherals. Those are best tested by reverse engineering what you have constructed and comparing with what you intended.
It is nice to build the same way as a lighthouse. Once on land, then dismantle and build again in the sea.
Thanks Old Hector. Yes it has been build in their hundreds, based as we know by the great design by George of Tubelabs.
Due to purchase costs, import duties, and lots of stress i am being extremely cautious and i will not rush the build.
Yes, this build has taken me far too long, but with limited free time this is what i am faced with.
I do appreciate all the guidance by all the posters, so thanks again all.
Due to purchase costs, import duties, and lots of stress i am being extremely cautious and i will not rush the build.
Yes, this build has taken me far too long, but with limited free time this is what i am faced with.
I do appreciate all the guidance by all the posters, so thanks again all.
I've managed to quickly changed back to the 240V tap.
The bulb is still connected, so considering results, i'll now remove the bulb.
With the ECC81's and EL84 inserted i have: -
T1-GRN-1}
T1-GRN-2} 6VAC
Without the valve rectifier Sovtek 5AR4 i have: -
T1-YEL-1}
T1-YEL-2} 5.2VAC
And the 600VAC I have: -
T1-RED-1 }
T1-RED-3 } 602V
Things are looking good
The bulb is still connected, so considering results, i'll now remove the bulb.
With the ECC81's and EL84 inserted i have: -
T1-GRN-1}
T1-GRN-2} 6VAC
Without the valve rectifier Sovtek 5AR4 i have: -
T1-YEL-1}
T1-YEL-2} 5.2VAC
And the 600VAC I have: -
T1-RED-1 }
T1-RED-3 } 602V
Things are looking good
Just checked voltages again, without the in series light bulb.
ECC81's and EL84's inserted i have: -
T1-GRN-1}
T1-GRN-2} 6.4 VAC
Without the valve rectifier Sovtek 5AR4 i have: -
T1-YEL-1}
T1-YEL-2} 5.5 VAC
And at: -
T1-RED-1 }
T1-RED-3 } 640 VAC
I think i need to reduce the 6.4 VAC down to a safe 6.3 VAC, i don't want to over work them.
ECC81's and EL84's inserted i have: -
T1-GRN-1}
T1-GRN-2} 6.4 VAC
Without the valve rectifier Sovtek 5AR4 i have: -
T1-YEL-1}
T1-YEL-2} 5.5 VAC
And at: -
T1-RED-1 }
T1-RED-3 } 640 VAC
I think i need to reduce the 6.4 VAC down to a safe 6.3 VAC, i don't want to over work them.
If you look at the data sheet I sent you will see the limits for the heater voltage are 5.7...7V. You are very safe with 6.4V.
I'm more interested on the B+ when you plug the rectifier tube. 640 CT unloaded may result in B+ a bit high when loaded, depending on the power transformer wattage.
I'm more interested on the B+ when you plug the rectifier tube. 640 CT unloaded may result in B+ a bit high when loaded, depending on the power transformer wattage.
Weekend gone, so back to the drawing board, with care...
I have my 100 watt bulb connected and can report these voltages: -
6.3V = 3.7 VAC
5V = 3.2VAC
B+ = 203 D.C.
Remove bulb and get out the fire extinguisher?
Or maybe a kick up the rear and get on with it!.............. don't answer that....
I have my 100 watt bulb connected and can report these voltages: -
6.3V = 3.7 VAC
5V = 3.2VAC
B+ = 203 D.C.
Remove bulb and get out the fire extinguisher?
Or maybe a kick up the rear and get on with it!.............. don't answer that....