I have an Aikido with the older octal all in one board. My transformer is an Antek AS-1T230. The two 6V windings are in series to feed the LV regulator for series connected filaments. If I remember the B+ is around 300vdc. For 6SN7's, which I use, the manual recommends B+ of 300vdc from a 240Vac input.
thank you, I appreciate the info and will cross that bridge if needed. I still need a volume pot maybe 50k or 100k? not sure yet.
I must also determine what to do about the tall c14 caps on the PS-21.
I must also determine what to do about the tall c14 caps on the PS-21.
would it be better for the heaters to be in series or parallel? the transformers are cheap and although I have already ordered the 12vac transformer I c
an easily order something different. how about this torrid.
Part Number: 1182M9
| % Voltage Regulation | |
|---|---|
| Description | Power transformer, toroid, 50 VA, with 9V @ 5.56A secondary, 1182 Series |
 | |
| Downloads (Click to download) |  |
 | |
| Bulletins (PDF) | |
| Shipping Weight | 1.75 lbs (0.79 kg) |
| UNSPSC | 39121301 |
| UPC | 623980531304 |
| REACH Compliant | Yes (more info...) |
| RoHS Compliant | Yes (more info...) |
| Power Rating (VA) | 50 |
| Secondary (RMS) Series | 18V C.T. @ 2.78A |
| Secondary (RMS) Parallel | 9V @ 5.56A |
Last edited:
50VA at 7V 7A - 14VCT Power Transformer Antek AS-0507 This should keep that regulator happy.
50va is overkill if it's only for the Aikido. as the most current you need is about 2amps so a 20va would work.
I have been experimenting with tubes. I tried 4x 6N2P but the gain is too high at x45 (mu/2) so today will be trying 4xPCC88. (mu34)
Whatever I try, the distortion is very low with low level (10mv in) and line levels (about 1v out) but I am having trouble getting the best result for 8-10v RMS output to drive an EL34. 4v RMS is fine then the 2nd & 3rd harmonics increase rapidly.(8% THD at 10v)
I will see what happens with the PCC88s and then try Broskie's attenuator to identify whether the output tubes are being overdriven.
Maybe I need to increase B+ from 220v to over 280.
I have been experimenting with tubes. I tried 4x 6N2P but the gain is too high at x45 (mu/2) so today will be trying 4xPCC88. (mu34)
Whatever I try, the distortion is very low with low level (10mv in) and line levels (about 1v out) but I am having trouble getting the best result for 8-10v RMS output to drive an EL34. 4v RMS is fine then the 2nd & 3rd harmonics increase rapidly.(8% THD at 10v)
I will see what happens with the PCC88s and then try Broskie's attenuator to identify whether the output tubes are being overdriven.
Maybe I need to increase B+ from 220v to over 280.
Yep. Do the math. each channel about 20ma depending on tubes. so 240v AC at 50ma is adequate ie 12va or 20va erring on the conservative side.
The input & output tubes are in series so the Ik flows through each pair. If it was 10ma, then total per channel is 20ma.
The input & output tubes are in series so the Ik flows through each pair. If it was 10ma, then total per channel is 20ma.
AS-05T240
AS-05T240 - 50VA 240V Transformer
$29.00
SKU:
00000103
Weight:
2.00 LBS
Shipping:
Calculated at checkout
Current Stock:
65
Quantity:
Buy in bulk and save
Product Description
Power transformer for tubes. Has 240V coil with 220V tap and 2 of the 6.3V 2A coil.
Electrical Characteristics
| Output Voltage | Current |
|---|---|
| Outputs | 3x |
| Power | 50VA |
| 240V | 0.1A |
| 220V | 0.1A |
| 6.3V | 2A |
| 6.3V | 2A |
Find Similar Products by Category
how about this .. 1 transformer for the B+ and heaters?
Ideally 6.3v AC is a bit low. 7 -9 would be better if you can find one.
However, the Ld1085 regulators are low drop out types so may be okay.
Also depends on what your mains voltage is. Mine is about 245v so a 230v transformer does output about 5% higher,
However, the Ld1085 regulators are low drop out types so may be okay.
Also depends on what your mains voltage is. Mine is about 245v so a 230v transformer does output about 5% higher,
Crooner:
6.3 volt AC might not give you regulated 6.3 volts DC. There are diode losses to consider. A full wave bridge will lose 2 volts. Read the page in the PS-21 manual on rectifier circuits and note the formula for full-wave bridges. You will note that by the time 6.3 volts is rectified, minus the diode losses the result is 6.8 volts. 6.8 minus 1 for the regulator (its dropout voltage) leaves less than 6 volts DC!!!!!
Diode loss is a fixed voltage. This doesn't account for very much at higher voltages but can be problematic at 6.3 volts. The LD1085 requires at least 1 volt more at the input than at the output to regulate properly. A 2 to 4 volt delta is better.
Running Broskie's formula again at 12.6 volts results in a raw DC of 15.6 volts. Subtracting 12.6 from 15.6 leaves a 3 volts buffer for the regulator to work with. Exactly where you want to be. Too little voltage delta and the reg won't reg properly and too much (roughly more than a 5 or 6 volt delta) and you'll have a lot of heat to dissipate from the reg.
So it's best, in my view, if you set the jumpers on your Aikido board for 12 volt filament operation. Or not, see below.
My go-to recommendations for transformers are Triads but the one needed for filament operation is out of stock at both Mouser and Digi-Key until October.
If you don't mind going the EI trans route there are the Hammonds. A 185D24 for filaments (Digi-Key, in stock) and for B+ the 185C230 (Digi-Key, in stock).
The AS-05T240 from Antek you mentioned above, won't cut it for filament duty but would be fine for B+. If you add the AS-0507 (two windings, 7 volts each) from Antek you'll be good to go with 6.3 volts on your Aikido filaments, if 6.3 volts is your preferred filament voltage. Just don't use the filament windings on the AS-05T240. At $29 plus $20 the Anteks the best deal going.
Cheers, S.
6.3 volt AC might not give you regulated 6.3 volts DC. There are diode losses to consider. A full wave bridge will lose 2 volts. Read the page in the PS-21 manual on rectifier circuits and note the formula for full-wave bridges. You will note that by the time 6.3 volts is rectified, minus the diode losses the result is 6.8 volts. 6.8 minus 1 for the regulator (its dropout voltage) leaves less than 6 volts DC!!!!!
Diode loss is a fixed voltage. This doesn't account for very much at higher voltages but can be problematic at 6.3 volts. The LD1085 requires at least 1 volt more at the input than at the output to regulate properly. A 2 to 4 volt delta is better.
Running Broskie's formula again at 12.6 volts results in a raw DC of 15.6 volts. Subtracting 12.6 from 15.6 leaves a 3 volts buffer for the regulator to work with. Exactly where you want to be. Too little voltage delta and the reg won't reg properly and too much (roughly more than a 5 or 6 volt delta) and you'll have a lot of heat to dissipate from the reg.
So it's best, in my view, if you set the jumpers on your Aikido board for 12 volt filament operation. Or not, see below.
My go-to recommendations for transformers are Triads but the one needed for filament operation is out of stock at both Mouser and Digi-Key until October.
If you don't mind going the EI trans route there are the Hammonds. A 185D24 for filaments (Digi-Key, in stock) and for B+ the 185C230 (Digi-Key, in stock).
The AS-05T240 from Antek you mentioned above, won't cut it for filament duty but would be fine for B+. If you add the AS-0507 (two windings, 7 volts each) from Antek you'll be good to go with 6.3 volts on your Aikido filaments, if 6.3 volts is your preferred filament voltage. Just don't use the filament windings on the AS-05T240. At $29 plus $20 the Anteks the best deal going.
Cheers, S.
The AN-0207 doesn't have the current you need. Two 6SN7s in parallel require 1.2 amps. Note the formula for a full-wave rectifier in the PS-21 manual: Current out (DC) = Current in (AC) /1.8 The AN0207 is rated at 1.8 amps on each winding so it's really only good for 1 amp DC. That's why I recommended the AS-0507. It's rated at twice the current for only 7 bucks more!
The Hammond you mentioned above is fine, though expensive compared to the AS-05T240. You will only need 20 to 30mA DC from the B+ supply. The AS-05T240 will give you roughly 60mA DC, so it will work well. If you aren't using it's 6 volt windings it won't be very stressed at all.
Your choice,
S.
The Hammond you mentioned above is fine, though expensive compared to the AS-05T240. You will only need 20 to 30mA DC from the B+ supply. The AS-05T240 will give you roughly 60mA DC, so it will work well. If you aren't using it's 6 volt windings it won't be very stressed at all.
Your choice,
S.
I had ordered the as-0507 and then canceled it. I appreciate the help, but I've ordered and canceled 6 transformers so far.
I will be keeping the Hammond transformer even though it is more expensive.
I have reordered the as-0507 for the heaters.
I will be keeping the Hammond transformer even though it is more expensive.
I have reordered the as-0507 for the heaters.
What you have (finally) on order should work out well. I like to keep a little space between transformers, 4" minimum, even though it shouldn't matter that much with toroids. Good, luck!
Thank you, still haven't decided on the enclosure/chassis, but I will keep the 4" spacing between transformers in mind.
Just a brief note to say that my Aikido EL34 driver stage is working well.
I use a PCC88 for the input and an ECC82 (12AU7) for the output. Gain is ~13 and 1.5v RMs in gives 20v RMS out at less than 1% 2ndH distortion.
Runs on 200v from 240v and 12v toroids.
I use a PCC88 for the input and an ECC82 (12AU7) for the output. Gain is ~13 and 1.5v RMs in gives 20v RMS out at less than 1% 2ndH distortion.
Runs on 200v from 240v and 12v toroids.