Output Transformers For Sale, December 2008

The output transformers for sale here were made in Australia over the last 12 years by a local amplifier maker, Elson Silva of Sydney.
He employed a master craftsman winding expert, Bruce Flanagan, who worked for 40 years in the electronics industry and who has recently retired.

The 16 different types of transformer listed below are about a third of the total number of output transformers I have for sale.
I can arrange to supply a compatible set of iron wound parts including a power transformer, an output transformer and choke for B+ filtering to suit a monoblock or dual channel chassis.  Let me know what you intend doing with your project and I can assist to ensure what I have will suit you.
 


This shows part of my present stocks of transformers for sale.

For other information about these transformers and their use and the sale conditions go to Output Transformer Notes, December 2008.

Every transformer described has the following listed information and allows anyone to calculate all other transformer design parameters :-

Weight  in Kilograms; 1Kg = 2.25 pounds.
Overall size as shown, Length horizontally across the two C-cores, Width across the external windings, Height of C-cores including clamping straps.
These dimensions are taken with the transformers oriented as they appear in the pictures. Dimensions all in millimetres, 25.4mm = 1.0 inches.
Anode Load to Speaker Load ratios for Push-Pull and Single Ended use.
Clipping Power, Class AB1 PP or SE class A1. The amount of class A1 within PP amps is a variable depending on the Idc at the OPT CT.
Ea is the supply dc voltage applied between cathodes and transformer input excluding cathode biasing if used. Eg2 is the screen voltage used with nominated tubes if beam tetrode or pentode is employed; Ea = Eg2 for triode and UltraLinear.
Core dimensions are usually given as T x S x L x H for E&I laminations. Tongue is the width of the central leg of the iron penetrating the winding,                    Stack is the height of the lamination stack penetrating the winding, and the winding window size is Length of window, x Height of window. With double C-cores, the Tongue = twice the strip build-up thickness of one '0' of the double '00' arrangement and the stack is the strip width used to wind the core. Dimensions are all in millimetres.
Np is the number of Primary turns. The turns per layer and wire Cu diameter is given where possible. Ia maximum dc current is at 2 Amps per sq.mm.
Ns is the number of Secondary turns. The turns per layer and wire Cu diameter is given where possible.
The Interleaving pattern is the arrangement of Primary and Secondary winding sections.
Ips is the insulation between primary and secondary windings.
Price for One Pair.

OP1, Weight 7.4Kg, o/a size 176mm x 132mm x 138mm. 560:1or4,  843:1.5or6,  1k1:2or8,  1k7:3or12,  2k2:4or16,   2k8:5or20,   3k3:6or24,   4k4:8or32.  PP, Ea = +600V, Eg2 = +400V, 8 x 6550/KT88, 300W+ PP AB1, beam power mode, 2k2 : 4.      For Hi-Fi use UL or CFB, Ea = +500V and 6 x 6550/KT88 for 100W+ AB1, 2.8k:5 ohms; proportion of class A1 power = 30W. Multiple EL34, triode possible. SE CFB, SEUL, +air gap, 40W into 840:6 ohms, 4 x 6550, 6 x EL34, Ea = +300V, Ia = 320mA. SE Triode, +air gap, 40W into 840:6 ohms, 6 x 6550, 6 x EL34, Ea = +420V, Ia = 325mAdc. Primary = 1,496t of 0.45dia, 11 layers 136t.  Secondary = 12 layers 63t of 1.0dia, Ns = 63 or 126. PP Interleaving = 11P x 12S,  Ips = 0.22 Nomex. Core = 52/52/76/28. Price, 1 pair available, aud $800.00 for the pair.

OP2, Weight 7.6 Kg,  oa size195mm x 130mm x 153mm. 1k4:4or1,  1k75:5or1.3,  2k1:6or1.5,   2k8:8or2,  3k5:10 or 2.5, 4k2:12or3,   5k6:16or4. PP, Ea = +600V, Eg2 = +400V, 8 x 6550/KT88, 300W+ PP AB1, beam power mode, 2k1:6ohms. For Hi-Fi use UL or CFB use Ea = +400V and 6 x 6550/KT88/KT90 or 8 x EL34/6CA7 for 100W+ AB1, 1k2:4 ohms; proportion of class A1 power = 24W. SE, Hi-Fi, CFB, SEUL, +air gap, 54W into 1k3:6 ohms, 6 x EL34. Ea = +415V, Ia = 320mAdc. SE Triode mode, 44W, 6 x 6550, Ea = +485V, Ia = 300mAdc. Primary = 868 turns of 0.45dia plus 2 x 181 turns of 0.3dia  each side of the 868t for a total of 1,230t for PP. For SE, Np is configured with 181t in parallel for 1,049t to allow Idc up to 325mAdc. For PP calcs, use Np = 1,230t, 0.3mm dia, 200mAdc max each side. Ns =  35 or 70, 8 x 35tpl, 1.8mm dia. Core = 56/50/76/28, PP Interleaving = 9P x 8S,  Ips = 0.22 Nomex. Price, 1 pair available, aud $800.00 for the pair.

OP3, Weight 5.6Kg, o/a size 150mm x 140mm x 133mm. 870:1or4, 1k3:1.5or6,  1k7:2or8,  2k6:3or12, 3k5:4or16, 5k2:6or24. PP, Ea = +600V, Eg2 = +400V, 8 or more 6550/KT88, 250W+ PP AB1, beam tetrode, 1k7:2or8. Hi-Fi use, UL or CFB, Ea = +500V and 6 x 6550/KT88/KT90 for 118W AB1, 3k5:4 ohms; proportion of class A1 power = 33W. Lower power PP triode OK. SE, CFB, SEUL, +air gap, 44W into 1k3:6ohms, 4 x 6550. Ea = +365V, Ia = 300mAdc. SE Triode mode 4 x 6550, 31W into1k3:6, Ea 415V, Ia 240mA. SE, CFB, SEUL, 60W into 1k3:6, 6 x 6550, Ea = +445V, Ia = 325mAdc. Triode mode, 44W, 6 x 6550, Ea +500V, Ia 300mA. Primary = 2,360t of 0.6dia, 20 layers 118t.  Secondary = 10 layers 80t of 1.0dia, Ns = 80 or 160. PP Interleaving = 10P x 10S,  Ips = 0.22 Nomex. Core = 38/50/88/33. Price, 1 pair available, aud $600.00 for the pair.

OP4, Weight 5.5Kg, o/a size 152mm x 105mm x 130mm. 1k9:3or12,   2k5:4or16,   3k2:5or20,  3k8:6or24,  5k0:8or32. PP, Ea = +500V, Eg2 = +400V, 4 or more 6550, 100W+ PP AB1, beam power mode, 2k5:4. For Hi-Fi use UL or CFB, Ea = +450V and 4 x 6550 for 90W AB1, 2k5:4 ohms; proportion of class A1 power = 20W+. Multiple EL34, 6L6 possible as well as triode operation. SEUL, CFB, tetrode, +air gap, 32W into 3k0:4.7 ohms, 3 x 6550, Ea = +485V, Ia = 150mAdc, SE Triode, 25W 2k5:4, 4 x EL34, Ea = +485V, Ia = 150mAdc. Primary = 1,661t of 0.3dia, 11 layers 151t.  Secondary = 10 layers 66t of 0.75dia, Ns = 66 or 132. PP Interleaving = 11P x 10S,  Ips = 0.22 Nomex. Core = 48/50/62/25. Price, 1 pair available, aud $600 for the pair.

OP5,  Weight 5.5Kg, o/a size 152mm x 140mm x 133mm. 2k1:4or16,   2k6:5or20,    3k2:6or24,  4k2:8or32. PP, Ea = +500V, Eg2 = 400V, 4 or more 6550, 90W+ PP AB1, beam tetrode mode, 2k1:4 For Hi-Fi use UL or CFB, Ea = +450V and 4 x 6550/KT88/KT90 for 90W AB1, 2k6:5 ohms; proportion of class A1 power = 20W+. Multiple EL34, 6L6 possible as well as triode operation. SE, CFB, SEUL, beam tetrode, +air gap, 30W, 3k2:6 ohms, 3 x 6550, Ea = +500V, Ia = 150mAdc. SE Triode,  22W 3k2:6,  3 x 6550, Ea + +500V, Ia = 150mAdc. Primary = 1,520t of 0.3dia, 10 layers 152t.  Secondary = 11 layers 66t of 0.75dia, Ns = 66 or 132. PP Interleaving = 10P x 11S,  Ips = 0.22 Nomex. Core = 48/50/62/23. Price, 2 pairs available, aud $600.00 for 1 pair.

OP6, Weight 5.2Kg, o/a size 140mm x 94mm x 118mm. 1k0:3or12,  1k3:4or16,  1k6:5or20,  2k6:8or32. PP, Ea = +430V, Eg2 = 400V, 4 or more 6550/KT88, 6 x EL34, 80W+ PP AB1, UL mode, 2k6:8. For Hi-Fi, UL or CFB, Ea = +400V, 4 x 6550/EL34 for 70W AB1, 2k6:8 ohms; proportion of class A1 power = 30W+. PP Trioded 6550/EL34 possible, less power. SE, CFB, SEUL, +air gap,  46W, 2k2:7, 4 x 6550, Ea = +500V, Ia = 200mAdc. SE Triode, 33W, 1k9:6, 4 x 6550, Ea = +500V, Ia = 200mAdc. Primary = 1,540 of 0.35dia, 11 layers 140t.  Secondary = 12 layers 80t of 0.55dia, Ns = 86 or 172. PP Interleaving = 11P x 12S,  Ips = 0.22 Nomex. Core = 44/38/62/22. Price, 1 pair available, aud $550 for the pair.

OP7, Weight 3.2Kg, o/a size 100mm x 108mm x 105mm.                                                                           864:1or4, 1k3:1.5or6,  1k7:2or8,  2k6:3or12, 3k5:4or16, 5k2:6or24, 6k8:8or32.                             PP, UL, CFB, beam tetrode, Ea = Eg2 = 400V, 2 x 6550, 48W AB1, 4k0:4.7 ohms. SE, CFB, SEUL, +air gap, 18W, 1k7:8, 2 x 6550, Ea = +300V, Ia = 150mAdc. SE Triode, 15W, 1k4:6.6 ohms, 3 x EL34, Ea = +400V, Ia = 150mA. Primary = 1,694t of 0.35dia, 14 layers 121t.  Secondary = 8 layers 59 of 0.85dia, Ns = 59 or 118.   PP Interleaving = 7P x 8S,  Ips = 0.22 Nomex. Core = 25/50/62/22. Price, 1 pair available, aud $400.00 for the pair.

OP8,  Weight 4.3g, o/a size 150mm x 100mm x 105mm. 1k5:6or1.5,   2k:8or2,    3k:12or3,   4k:16or4,   5k1:20or5,   6k1:24or6,  8k2:32or8. PP, UL, CFB, beam tetrode, 4 x 6550, Ea = +450V, Eg2 = 400V, 80W+ PP AB1, 4k:4. 50W with PP triodes. SEUL, CFB, +air gap, 35W, 1k5:6, 4 x EL34, Ea = +350V, Ia = 260mAdc. SE Triode,  25W, 1k5:6, 4 x 6550, Ea = +500V, Ia = 220mA. Primary = 1,920t, 0.45dia, 16 layers 120t, Secondary = 8 layers of 60t, 0.9dia, Ns can be 60 or 120. PP Interleaving = 9P x 8S,  Ips = 0.22 Nomex. Core = 46/38/65/25. Price, 1 pair available, aud $480.00 for the pair.

OP9, Weight 2.6Kg, o/a size 102mm x 95mm x 95mm. 1k3:2or8,   1k9:3or12,   2k5:4or16, 3k2:5or20, 3k8:6, 5k0:8or32. PP, UL, CFB, beam tetrode, Ea = Eg2 = 400V, 2 x EL34, 30W AB1, 5k0:8 ohms.  With Ea =          +350V, get 22W pure class A1, 5k0:8. SE, CFB, SEUL, +air gap, 18W, 4k5:7 ohms, 2 x EL34, Ea = +450V, Ia = 100mAdc. SE, CFB, SEUL, +air gap, 18W, 1k3:8 ohms, 2 x EL34, Ea = +275V, Ia = 175mAdc. SE Triode, 14W, 3k2:5 ohms, 3 x EL34, Ea = +450V, Ia = 100mA. Primary = 2,160t, 0.35dia, 18 layers 120t.  Secondary = 9 layers 86t, 0.55dia, Ns = 86 or 172. PP Interleaving = 10P x 9S,  Ips = 0.22 Nomex. Core = 25/38/62/22. Price, 1 pair available, aud $400 for the pair.

OP10, Weight 2.6Kg, o/a size 102mm x 95mm x 95mm. 2k0:1or4,  3k0:1.5or6,  4k0:2or8,  6k0: 3or12, 8k0:4or16, 12k0:6or24, 16k0:8or32. PP, UL, CFB, beam tetrode, Ea = Eg2 = 400V, 2 x EL34, 30W AB1, 4k0:8 ohms. With 12k0:6,   get 22W pure class A1. SE, CFB, SEUL, +air gap, 17W, 4k0:8 ohms, 2 x EL34, Ea = +450V, Ia = 110mAdc. SE, CFB, SEUL, +air gap, 18W, 3k0:6 ohms, 2 x EL34, Ea = +360V, Ia = 120mAdc. SE Triode, 12W, 2k3:4.7 ohms, 2 x EL34, Ea = +400V, Ia = 110mA. Primary = 2,688t, 0.28dia, 16 layers 168t.  Secondary = 8 layers 59t, 0.85dia, Ns = 59 or 86 or118. PP Interleaving = 9P x 8S,  Ips = 0.22 Nomex. Core = 25/38/62/22. Price, 1 pair available, aud $400.00 for the pair.

OP11,  Weight 3.2Kg, o/a size 102mm x 95mm x 95mm. 1k2:4,  1k5:5,   1k8:6, 2k4:8,   PP, UL, CFB, beam tetrode, Ea = Eg2 = +400V, 4 x EL34, 60W AB1, 2k4:8 ohms. With Ea = +300V, 45W, 4 x EL34, 2k4:8, more class A with higher Ia. SE, CFB, SEUL, +air gap, 25W, 1k5:5, 3 x EL34, Ea = +350V, Ia = 200mAdc.  SE Triode, 17W, 1k5:5 ohms, 3 x EL34, Ea = +400V, Ia = 160mA. Primary = 1,696t, 0.4dia, 16 layers 106t.  Secondary = 9 layers 98t, 0.45dia, Ns = 98. PP Interleaving = 10P x 9S,  Ips = 0.22 Nomex. Core = 26/50/62/22. Price, 1 pair available, aud $400.00 for the pair.

OP12,  Weight 4.0Kg, o/a size 115mm x 90mm x 98mm. E&I laminated  core, GOSS. 2k0:2or8,   3k0:3or12,  4k0:4or16,  5ko:5or20,  6k0:6or24, 8ko:8or32.   PP, UL, CFB, beam tetrode, Ea = Eg2 = +400V, 2  x  EL34, 40W AB1, 6k0:6 ohms. With Ea = +300V, 25W, 2 x EL34, 6k0:6, more class A with higher Ia. SE cannot be done with this transformer because the E&I laminations cannot easily be air gapped. Primary = 2,592t, 0.28dia, 16 layers 162t.  Secondary = 8 layers 81t, 0.5dia, Ns = 81 or 162. PP Interleaving = 9P x 8S,  Ips = 0.22 Nomex. Core = 38/40/57/19. Price, 1 pair available, aud $300.00 for the pair.

OP13,                                                                                           Weight 2.6Kg, o/a size 100mm x 75mm x 82mm. E&I laminated  GOSS core.                                   1k9:8  , k9:2or8,   2k9:3or12,  3k9:4or16,  4k9:5or20,  5k9:6or24, 7k9:8or32.                                  PP, UL, CFB, beam tetrode, Ea = Eg2 = +350V, 2  x  EL34, 25W AB1, 5k9:6, SE cannot be done with this transformer because the E&I laminations cannot easily be air gapped. Primary = 2,000t, 0.28dia, 16 layers 125t.  Secondary = 4 layers 63t,0.6dia, Ns = 63 or 126. PP Interleaving = 5P x 4S,  Ips = 0.22 Nomex. Core = 32/40/48/12. Price, 1 pair available, aud $180 for the pair.

OP14,  Weight 3.2Kg, o/a size 102mm x 95mm x 95mm. 1k2:4,  1k5:5,   1k8:6, 2k4:8,   PP, UL, CFB, beam tetrode, Ea = Eg2 = +400V, 4 x EL34, 60W AB1, 2k4:8 ohms. With Ea = +300V, 45W, 4 x EL34, 2k4:8, more class A with higher Ia. SE, CFB, SEUL, +air gap, 25W, 1k5:5, 3 x EL34, Ea = +350V, Ia = 200mAdc.  SE Triode, 17W, 1k5:5 ohms, 3 x EL34, Ea = +400V, Ia = 160mA. Primary = 1,696t, 0.4dia, 16 layers 106t.  Secondary = 9 layers 98t, 0.45dia, Ns = 98. PP Interleaving = 10P x 9S,  Ips = 0.22 Nomex. Core = 26/50/62/22. Price, 1 pair available, aud $400.00 for the pair.

OP15, Weight 3.2Kg, o/a size 102mm x 95mm x 95mm. Only SE possible.                                                   1k3:2or8,  1k9:3or12,  2k6:4or16, 3k2:5,  3k8:6or24, 5k1:8or32.   SEUL, SECFB, +air gap, 25W   3k2:5, 3 x EL34, 2 x 6550, Ea = 410V, Ia = 140mAdc. SE Triode, 16W, 3k2:5 ohms, 3 x EL34, 2 x 6550, Ea = +460V, Ia = 125mA. Primary = 2,440t, 0.35dia, 20 layers 122t.  Secondary = 10 layers 96t, 0.5dia, Ns = 96 or 192. PP Interleaving = 11P x 10S,  Ips = 0.22 Nomex. Core = 26/50/62/22. Price, 1 pair available, aud $400.00 for the pair.

OP16, Weight 3.8Kg, o/a size 115mm x 105mm x 102mm. Only SE possible.           1k5:2or8,  2k3:3or12,  3k0:4or16, 3k8:5,  4k6:6or24, 6k1:8or32.   SEUL, SECFB, +air gap, 19W   3k8:5, 2 x 6550, Ea = 420V, Ia = 120mAdc. SE Triode, 15W, 3k8:5 ohms, 3 x EL34, 2 x 6550, Ea = +480V, Ia = 110mAdc. Primary = 1,830t, 0.35dia, 15 layers 122t.  Secondary = 8 layers 66t, 0.75dia, Ns = 66 or 132. PP Interleaving = 9P x 8S,  Ips = 0.22 Nomex. Core = 32/50/62/22. Price, 1 pair available, aud $450.00 for the pair.

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