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Nigel's output transformer




 
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km6sn
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« on: December 14, 2019, 01:09:27 PM »

This is probably the best picture of Nigel's output transformer details.
The black wires connect to the drains. In the top center, both black
wires attach to the modulated VDD.

The bare wire is the output. One end is grounded, the other end
goes to the output network. Note the winding directions, and the
bridge-connection at the top of the image.


* xfmr-s.jpg (330.73 KB, 1024x768 - viewed 380 times.)
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YB1AHY
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« Reply #1 on: December 27, 2019, 02:15:57 AM »

Hii

I also paid attention to the picture and I tried to find references about the direction of the coil but could not find it. it looks like the direction of the flux will cancel each other out. Or because of each pulse cycle treated as single ended.

Best Regards


Agus.
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vk3alk
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« Reply #2 on: December 27, 2019, 03:27:14 AM »

I think its this.... as per photo uploaded.....


Wayne



* Nigels Output Transformer.JPG (326.04 KB, 1600x1200 - viewed 304 times.)
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N4LTA
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« Reply #3 on: January 04, 2020, 03:22:17 PM »

This is how I wound a couple. This one is for a 100 Watt test rig. On a T157-2 corefor 100 Watts. I have another wound or a T225-2 for 400 watts or so.

Pat
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* IMG_3926.jpg (95.67 KB, 640x480 - viewed 152 times.)
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M0VRF
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« Reply #4 on: January 05, 2020, 04:55:12 AM »

Windings need to be opposed, it looks like you've wound in the same direction for both sides which won't work (I made the same mistake). Just use 2 separate transformers then windings don't care.
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N4LTA
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« Reply #5 on: January 05, 2020, 09:59:18 AM »

Thanks for the catch.  Looking at Nigel's photo, you are correct.  I'll change that. Does this look better?

Changing to two transformers may make things simpler.

Pat
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* IMG_3933.jpg (94.46 KB, 640x480 - viewed 157 times.)
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M0VRF
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« Reply #6 on: January 05, 2020, 12:31:08 PM »

Yep, that's better.

Things get rather cramped on 40m but fine for my application. If you want a higher Z (>6R) then you'll need more turns and a bigger core.

I used 6T per side on a stacked pair of T200's on 40m and the Z was 5R5.

On 80m I had to go to separate 1:1 transformers.

J.
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N4LTA
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« Reply #7 on: January 05, 2020, 07:54:43 PM »

I probably will use two transformers for the 400 watt transmitter. This transformer is for a couple of SiC MOSFETS in a test setup. Hope to make some RF in the next few days.

What capacitance are you using on 80 from drain to ground?

Thanks

Pat
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M0VRF
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« Reply #8 on: January 07, 2020, 01:05:58 AM »

Can't remember (only used 80m for initial testing years ago) but I use 270pF each side for 40m as the caps are dirt cheap from Farnell.

Probably 1nF, not critical anyway as they have little effect other than to keep the Voltage to a sane level.

Just adjust to give 3.5 X Vcc at drain.

Use 1nf, you'll be fine.
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km6sn
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« Reply #9 on: January 07, 2020, 09:18:52 AM »

M0VRF: what specific cap part number are you using for drain-to-ground?
I am trying to identify source of low ESR caps. 73, Rod
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M0VRF
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« Reply #10 on: January 07, 2020, 11:42:34 AM »

2420175

They seem fine and am sure another chap on here recommended them.

Regards

JB.

p.s. just do a search on here for 270pF, its was GW0FZY.
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YB1AHY
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« Reply #11 on: January 13, 2020, 06:30:23 PM »

I think its this.... as per photo uploaded.....


Wayne



i did try Nigel's transformer configuration and it works great.

i use for 2 x FQPF8N60 drive by 2 IXDD614 with 30 Volt VDS Id 2 Amps producing 50 Watt RF.

Waveform precisely looks like class E in each drains with opposite phase. at first to much shunt caps, after several time tuning i found 700 pF is a good one.

Agus





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vk3alk
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« Reply #12 on: January 13, 2020, 08:18:05 PM »

Fantastic Agus....

Maybe posting a picture would be good and also one with the waveforms....

Be interesting to see the peak value they reach.....



Wayne
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YB1AHY
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« Reply #13 on: January 22, 2020, 04:26:34 AM »

Fantastic Agus....

Maybe posting a picture would be good and also one with the waveforms....

Be interesting to see the peak value they reach.....



Wayne


Here is my photos and waveform from each drain


agus


* amatir001.jpg (194.83 KB, 1024x1365 - viewed 242 times.)

* amatir002.jpg (121.79 KB, 1024x1365 - viewed 155 times.)
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steve_qix
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« Reply #14 on: January 22, 2020, 10:03:19 AM »

Beautiful waveforms (no ringing!).  What is your DC voltage when producing these waveform?  What is the peak voltage of the waveform?

Nice!
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High Power, Broadcast Audio and Low Cost?  Check out the class E web site at: http://www.classeradio.org
vk3alk
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« Reply #15 on: January 22, 2020, 04:33:35 PM »

Agus ... what carrier power level are you planning to run from your TX ?


Actually Steve the waveform looks super....
Are getting a little confused between Agus and Pats drain waveforms though....
From what I know CMCD drain waveforms are Class E looking like what Agus has...
Pats are more square which is more like VMCD......
Their output stages are similar....


Wayne
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YB1AHY
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« Reply #16 on: January 22, 2020, 10:04:11 PM »

Beautiful waveforms (no ringing!).  What is your DC voltage when producing these waveform?  What is the peak voltage of the waveform?

Nice!

Hi Steve and Wayne

Thank you for comment, i put 30 Volt and consuming 2 amps, the rf out was 50 watts.  the peak waveform was 63 Volt, i am using variable PSU and i try from 15 - 30 volt and i noticed that peak is about 2,2 times supply voltage. i believe it is class D, but i still suspicious this is balance class E regarding to waveform (i cannot prove it i m not a mathematician hehe).

The primary transformer winding is looks like at resonance with Cshunt + Coss but a little broader in bandwidth.  when i put too much on Cshunt + Coss the waveform precisely like like Mr Nathan Sokal paper.

To make it good waveform, a also do the Mosfet driver voltage adjustment,  i use IXDD614 and i found out only need 7 Volt. Before it was overdrive (12V) and it looks like Mosfet become open momentarily when period it should be close

Thats what i have so far.

73s agus.
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vk3alk
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« Reply #17 on: January 23, 2020, 03:04:52 AM »

Hi Agus...

What carrier power level are you planning to use....?


Wayne
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YB1AHY
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« Reply #18 on: January 24, 2020, 02:48:23 AM »

Hi Agus...

What carrier power level are you planning to use....?


Wayne

RF deck (class D) that I tried actually is Driver for my analog Class E RF Deck. It designed for 15 Watt max out. Because of Nigel's transformer configuration, I was tempted to try it. so I changed the configuration, but it turned out better than before.

carrier level is designed for 15 Watts max, but I try to 50 watts. When operating at 50 watts, the transformer gets hot quickly

73s

agus
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M0VRF
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« Reply #19 on: January 24, 2020, 12:28:42 PM »

You should be able to generate a lot more power but you will need a higher voltage.

I use a stacked pair of T157-2's with a similar config and using 4 FETs and 24V gives 100W, so 400W at 48V.

This is the limit tho' as things are warming up as current is 10A (at 48V).

Secret is to use a much higher voltage, have more turns on the toroidal o/p tran and run a much higher Z keeping the current down, keeping I2R losses down and hence efficiency high.

PSUs above 48V however are either very expensive or you have to make your own, hence my decision to use 48V as smpsu's are dirt cheap.

For 15W you could just use and IRF510 in single ended simple design without the complexity of push pull.

J
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N4LTA
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« Reply #20 on: January 25, 2020, 01:14:57 PM »

M0VRF

Can you make sure that I have the proper idea on using two transformers for 80 meters

I will wind one as Nigel did  for supplying Vdd

I will wind another as a straight 1 : 1 transformer with the primary winding across the two drains and the secondary winding to the output terminal and to ground. Thanks in advance.

Pat
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M0VRF
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« Reply #21 on: January 27, 2020, 05:21:18 AM »

Yes, exactly, just a single 1:1 per side.

https://azure.wgp-cdn.co.uk/app-radio-enthusiast/posts/Fig6bmnh.png

Simples!

J.
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YB1AHY
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« Reply #22 on: January 30, 2020, 12:46:10 AM »

You should be able to generate a lot more power but you will need a higher voltage.

I use a stacked pair of T157-2's with a similar config and using 4 FETs and 24V gives 100W, so 400W at 48V.

This is the limit tho' as things are warming up as current is 10A (at 48V).

Secret is to use a much higher voltage, have more turns on the toroidal o/p tran and run a much higher Z keeping the current down, keeping I2R losses down and hence efficiency high.

PSUs above 48V however are either very expensive or you have to make your own, hence my decision to use 48V as smpsu's are dirt cheap.

For 15W you could just use and IRF510 in single ended simple design without the complexity of push pull.

J

Hi.
Thank you for sharing experiences about what you have done will be a reference. Agree DRIVER is complex, I just want to try and prove the design of the Nigel's transformer. thank you for responding to my email.


73s
agus
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M0VRF
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« Reply #23 on: January 30, 2020, 01:03:32 AM »

Hi Agus, happy to help.

Not sure by what you mean re, 'DRIVER is complex' ??

It's a single chip is it not?

Regards.

JohnB.
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YB1AHY
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« Reply #24 on: January 30, 2020, 03:04:20 AM »

Hi Agus, happy to help.

Not sure by what you mean re, 'DRIVER is complex' ??

It's a single chip is it not?

Regards.

JohnB.

Just quote your statement For "15W you could just use and IRF510 in single ended simple design without the complexity of push pull".  That is the my 400 watt Class E RF Deck driver using sinewave.

BR
agus
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