I have. Nano is HUGE (because Bmax must be kept below 1T) and hell expensive. 50W PP transformer on picture weight almost 7 Kg (>15.4 lbs)
Designed and assembled just for curiosity. Amorphous is more or less OK in terms of cost and physical dimensions.
Attachments
You said precise - a nonsense...
!mW does mean nothing in this case matters for demonstration matters some smal signal at tthe input of the tube say 1V p-p and about the max signal of say 90 Vp-p
After power tube amplification that will be 2 very diferent amplitude signalas to OT.
If the transfer is dramaticaly deferent in LF region than we can talk about the "change" in relative permeability.
If it is NOT than the pretty clear will be - that there is no change within the signal amplitude...
And there will be NO even significant change in transfer or phase...
1mW output power is the power applied to the transformer. It is used to assess minimum inductance. It is common/standard procedure and it means it can't be worse that. Now that it's not convenient for you it doesn't matter? Where do you see such dramatic difference? 3Hz or 4Hz cut-off is a dramatic difference?You said precise - a nonsense...
!mW does mean nothing in this case matters for demonstration matters some smal signal at tthe input of the tube say 1V p-p and about the max signal of say 90 Vp-p
After power tube amplification that will be 2 very diferent amplitude signalas to OT.
If the transfer is dramaticaly deferent in LF region than we can talk about the "change" in relative permeability.
If it is NOT than the pretty clear will be - that there is no change within the signal amplitude...
And there will be NO even significant change in transfer or phase...
Besides, your 2A3 transformer dropping by 3 dB at 8Hz means it has 12H inductance if 2.5K or 14H (at best) if 5K. The problem is not frequency response, the problem is much higher distortion at low frequency.
Do you realize how comical is your rant about low frequency performance? A refrigerator transformer, after being gapped for DC current, might be better!
Last edited:
I would rather see something more down to earth
Is there anyone who has experience with modern core materials as nano, amorphous and such? Any different technics in windings using those cores?
Thank you all,
Andre.
Winding geometry should be indifferent to the core material in the HF region. Sometimes there can be some subtle differences, such as:
Top FR is using a HiB core, Bottom FR using a nanocrystalline core. There is a slight behavior change in the dip resonance located at ~200kHz
This transformer has 22Hy as I am remeber well...
It seems that You does not know that aproximate equivalent source impedance is internal resistance of the tube in parallel with load?
So it is not the load only, and source driving OT is surely much lower than You state 2.5K to 5K...
Do You realize noe how your internal permeability is low?
.
For the 4 time = does not matter power in this case voltage is primary parameter to compare with. And much easier to measure... Some Minimal value say 1Vp-p or less, and some max to 2x-Ug of the power tube. Say 90Vp-p
In this case it will be the difference of about 100 X it is more than enough to check Your claim and "calculations of huge difference in [Hy]
It shoud be for sure not 1Hz difference IF IT IS TRUE.
....
Last edited:
If it had 22H, it would not do 8Hz -3dB unless the measurement is wrong or one is not measuring the transformer alone. In the latter case the amplifier causing that drop for other reasons . I put a range from 2.5 to 5K because it was not specified. That is not going to make a massive difference because it's about equilavent resistance (i.e. plate resistance of the 2A3 in parall to nominal primary load). You can learn that from the Radiotron handbook if not clear.....
There is no 100x difference. Fram 1 mW and 26H, it goes to 35H full power. Effective permeability is 440 at 1 mW and 600 at full power. It is 1.36 factor or 36% increase. I uploaded a picture at post #134. Put an airg-gap, re-draw the magnetization with DC current and then draw the AC loop around the actuall DC magnetization for the small signal and large signal and see what you get. It's an AC loop because hysterisis will never diappear 100% (i.e. core loss willnever be zero).
The more you post and the more is clear that you are a novice with no experinece on the subject of output transformers.
There is no 100x difference. Fram 1 mW and 26H, it goes to 35H full power. Effective permeability is 440 at 1 mW and 600 at full power. It is 1.36 factor or 36% increase. I uploaded a picture at post #134. Put an airg-gap, re-draw the magnetization with DC current and then draw the AC loop around the actuall DC magnetization for the small signal and large signal and see what you get. It's an AC loop because hysterisis will never diappear 100% (i.e. core loss willnever be zero).
The more you post and the more is clear that you are a novice with no experinece on the subject of output transformers.
Last edited:
I cant remember now what was the -db cut off Fo, probaly was -1db. It was before 25 years ago...
No big deal, it can be simulated easily to get the more precise values in the circuit. Rdc was below 200ohms I think?
.
No big deal, it can be simulated easily to get the more precise values in the circuit. Rdc was below 200ohms I think?
.
I meant in the voltage input to the grid of the tube... 90Vp-p to say 0.9Vp-p of input
Center area 6x4cm, yet stacking factor for these types of cores is only 0.75. Material of course is the same, just coating color different. Unfortunately, coil design was unsuccessful. Someday I may build it again if I will have a mood to do so. Currently having very good 60W GOSS HiB transformers to proceed with my projects anyway (photo on the first page of this thread).
To LinuksGuru:
6x4 should be quite good for 60W PP OPT, even with 75% stacking, but that is for GOSS in MHO.
I wonder if you can share your thoughts about coil design, what made it unsuccessful for the exotic core you have tried It with. I understand the core material makes quite a difference, not only in permability and max magnetization, but also in the interaction with the coil structure.
Thank you,
Andre
6x4 should be quite good for 60W PP OPT, even with 75% stacking, but that is for GOSS in MHO.
I wonder if you can share your thoughts about coil design, what made it unsuccessful for the exotic core you have tried It with. I understand the core material makes quite a difference, not only in permability and max magnetization, but also in the interaction with the coil structure.
Thank you,
Andre
@AndreK, core material have nothing to do with coil structure directly, Bmax and dependent value of primary number of turns is what influences parasitic parameters. After all I've got too high stray capacitance, that is not good if amplifier have high dB value of GNFB. Permeability of nano core I have attached, in final unit it must be decreased with air gap. 6x4cm geometric nano core area is too small to build 60W PP transformer.
Attachments
Sure it does. You can use this as a trick to alter or redirect capacitance. I often reverse winding directions in projects. I would often dump capacitance into the primary region, where it is less offensive for the HF. My favorite capacitance distribution is ~ 50% to the primary, 50% primary to secondary.
Here's a quick simple example. If we take a single ended transformer with an P-S-P interleaving schematic. Let's asume grounded secondary and 12 overall layers of primary, which makes for P6-S-P6. Let's assume you begin with the anode connection at the start. Using the simplified Patrick Turner capacitance calculation technique, that translates to capacitance factor of (6,5/12)^2 + (5,5/12)^2.
If you reverse wind the top P6 section so that the B+ lead out ends up close to the secondary layer, the capacitance factors becomes 6,5/12^2 + 0,5/12^2, basically you have reduced the P/S capacitance by ~42%
However it increases primary to core to primary capacitance, but for most cases this capacitance is very small and one can safely dump into it.
It is also demonstrated on Crowhurst Papers. Reverse winding works more efficiently on less interleaved transformer and less efficiently with higher interleaves.
You can also split a chunk of primary section into combinations of reverse + right wound layers. This is extremely useful at near-anode levels. You can dump primary to secondary capacitance to primary to primary capacitance, squeezing some HF free lunch. The idea is to "break" the exponent, take advantage of the fact capacitance decreases exponentially with turns decreasing towards B+.
Furthermore diminishing capacitance by increasing dielectric thickness is also a useful trick, as caused Ls by thicker dielectric doesn't increase the same rate as the Cs, until a point. It's parrabolic and different for various P/S interface count, but one can also take advantage of this.
Or simply said, you can use higher thicknesses at high capacitance regions and low thicknesses at low capacitance interfaces, with a steeper decrease of Cs than Ls increase.
Furthermore diminishing capacitance by increasing dielectric thickness is also a useful trick, as caused Ls by thicker dielectric doesn't increase the same rate as the Cs, until a point. It's parrabolic and different for various P/S interface count, but one can also take advantage of this.
Or simply said, you can use higher thicknesses at high capacitance regions and low thicknesses at low capacitance interfaces, with a steeper decrease of Cs than Ls increase.
@50AE
Impressive and highly scientific..
From what I learn, it is quite different for the OTP if it is intended for triode or pentode output tube. Normally pentode is more immune to Ls,
triode to Cs, obviously due to Ri.
I am in triodes, so from my personal experience, I do 1/4P+3S+1/2P+3S+1/4P. Thick insulation between the P and S, no reverse windings. Primary in series,
secondary in series/parallel, and I use big *** cores.
Impressive and highly scientific..
From what I learn, it is quite different for the OTP if it is intended for triode or pentode output tube. Normally pentode is more immune to Ls,
triode to Cs, obviously due to Ri.
I am in triodes, so from my personal experience, I do 1/4P+3S+1/2P+3S+1/4P. Thick insulation between the P and S, no reverse windings. Primary in series,
secondary in series/parallel, and I use big *** cores.
Last edited:
I'll borrow your theme a bit. I am buying a CNC winding machine. I have seen this:
https://ukcnc.net/index.php?route=product/product&path=62&product_id=52.
But the machine is very expensive. Do you have any other suggestions?
https://ukcnc.net/index.php?route=product/product&path=62&product_id=52.
But the machine is very expensive. Do you have any other suggestions?
The most important question is efficiency. If you decide on mass production of many transformers, you'll need to invest in fancy tooling, tentioners, etc. On the other hand, if you're after a few transformer to satisfy your DIY use, you can get away with a semi-automated hand winder and your fingers are wire guide + tentioner.
