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Nigel's 40M Transmitter




 
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Author Topic: Nigel's 40M Transmitter  (Read 7658 times)
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vk3alk
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« on: January 10, 2021, 07:25:25 AM »

Have just made an experimental version of Nigel 40M TX.....
Its going reasonably well for the first test....
Had it up to 130 watts carrier with an efficiency of just on 90%......
Are sure I can squeeze a little more and will rewind the output transformer a little differently.....
The loading is appox 16R .... will lower that a bit just to suit my test power supply....

But it seems to be in the ball park.....
Nigel claimed 92% using a LPF so are not far off I suppose....


Wayne


* Nigel 40M TX.JPG (472.33 KB, 1600x1200 - viewed 431 times.)
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N4LTA
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« Reply #1 on: January 10, 2021, 11:45:42 AM »

Wayne

Looks great.

I have been making some PC boards and hope my shop will be complete in two weeks. I have a design done for two FETs for a low power rig to drive an amplifier using Nigels circuit and the transformer that you are using. I also have redone my board for his PWM circuit . I have added a divide by two splitter and two regulated power supplies on board.

Seems like the shop area is taking way longer  than I hoped. The two work cabinets with drawers are holding things up.

Pat
N4LTA


* pwm board.JPG (104.37 KB, 693x454 - viewed 306 times.)

* 2 fet xmitter.JPG (48.34 KB, 347x490 - viewed 300 times.)
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vk3alk
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« Reply #2 on: January 10, 2021, 04:52:19 PM »

Hi Pat...

Ok on your shop and the cabinets....
Those boards look good to me and nice short tracks to the gates on the TX board....

Have you tried the TX board out or are you waiting for the shop to be finished....

Probably at 90% efficiency the TX module would be OK to use now but will fiddle around to improve a little more....


Wayne
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vk3alk
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« Reply #3 on: January 11, 2021, 10:24:57 PM »

Pat it will be interesting to see how you go with that little TX board but will now probably end playing around with this transmitter.
Decreased the loading down from around the 20R to 10R and the efficiency dropped down as well to 88%...
Changed the primary from 5 turns either side to 4 turns and increased the secondary from 10 to 14T...
The Class E looking waveforms were rather high too and had to add some Shunt Capacitance to bring them down...
My T200-2 core gets hot at the 200 watt carrier mark so 150 watts maybe and with modulation probably might need 2 cores not sure...
If I was to use this TX would have to spend quite a bit of extra time fine tuning etc:....


Wayne


* Nigel maybe final test.JPG (467.59 KB, 1600x1200 - viewed 361 times.)
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M0VRF
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« Reply #4 on: January 12, 2021, 11:59:21 AM »

I have built a similar design many times now.

Stack a pair in the T200-2s or just use the -B version + your wire is too thin. I use 2mm for DC and 3mm PTFE coated for the RF side. You can get around 9t on each side. Using 2x48V supplies in series 200W carrier is no problem. For 100W just a single supply and 6t per side is fine. For 160/80 use the -1 variant and CREE Gen 3s.

Very simple and Very efficient!

JB.
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vk3alk
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« Reply #5 on: January 12, 2021, 04:36:57 PM »

Ok thanks for those comments....

It's a muck around project but will wind up one more transformer and see how it goes....

What efficiency were you getting with yours ?


Wayne
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vk3alk
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« Reply #6 on: January 12, 2021, 11:56:41 PM »

Made up another transformer using 1.8mm ECW for the primary and large multi strand copper wire for the secondary.
5T each side for the primary and 14T secondary giving a loading around 9-10R
Found it important to match the inductance on both sides equalizing the voltage of the Drain waveforms....
In my case had to use 150pF Shunt Capacitors to get the efficiency up as well...

Ran the TX at 150 watts and the single T200-2 core transformer was just warm so yes the larger wire is important...
Efficiency just over 90% .....

These push pull TXs are cantankerous ( is that how you spell it ) beasts .....

Anyway all this might help others if you decide on this build....

It probably still needs more fine tuning though but as an experiment its about as far as I will go..


Wayne


* Nigel output xformer.JPG (483.05 KB, 1600x1200 - viewed 363 times.)
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N4LTA
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« Reply #7 on: January 13, 2021, 10:29:49 AM »

Thanks Wayne for showing your experiment. I have not tested the boards 100% but parts of them are from previous projects and have been tested.

I can't do much of anything now as everything including tools test equipment and soldering equipment is all boxed up waiting for floor finishing that is happening now and cabinet hopefully done next week. I am working on hanging a 160 meter dipole during the next few days and then going to Key West for a week to get away from the cold weather  for a week. When I get back, hopefully I can get started moving in to my shop.

Pat
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M0VRF
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« Reply #8 on: January 13, 2021, 02:11:56 PM »

You can just use 1:1 turns ratio for the transformer the amount of turns sets the Z. You just conjugate match this to 50 R with series L and parallel C. Simple as, works every time and I now have values for all band's worked out. On 40m with 6:6t and a pair of T200-2s (I now use 184-2's) you'll get approx 5R, handy as you can use a commonly available 48V 10A supply for 100W carrier. To conjugate match this on 40m you'll need a rather small L, couple to 3t on T106-2 and series C of 1n2. Just fit 50R LPF after that.

I notice folk on here have an interest in thru' hole components, can't say I care for them at all and never give a tidy layout. SMT is simple neat and easy to do with a magnify glass and a hot air tool. Maybe I'm showing my (youthful?) Age!!

The 4 FET design is perfect for 200W with a higher voltage keeping the current low and efficiency high.

CREEs GEN 3s are now 60mR 40A and easily driven with an NCP81074A consuming around 60mA (per FET/per Driver)@12V on 160m, roughly the same I on 40m wi the GaNs.

Transphorm GaNs are still the Biz for 40m and 6V on the drivers is fine.

I've offered boards and kits before and had little interest so I'll keep them to myself!

Please contact me as I can supply part built (SMT parts fitted) PCBs, PM me for further info.

Regards to All.

JB.

p.s. attached a slightly older version of my current design (quad SiC 40m) I use for demos, not much has changed in the newer version other than using GaNs for this frequency.
Using the AD9850 is handy as it has opposing squarewave O/Ps so no need to divide anything and all that, just drive the drivers directly, simples..init!


* PXL_20210113_191739627.jpg (1910.47 KB, 2145x3053 - viewed 395 times.)

* Old SiC.png (69.1 KB, 681x812 - viewed 335 times.)
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vk3alk
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« Reply #9 on: January 13, 2021, 11:38:32 PM »

Ok Ok Ok I get it finally....

Thanks JH for your comments ....

93% efficiency  Smiley

Rewound the output core again  Grin
5T primary 6T secondary each side giving a 12R load...
For the series tuned circuit used a 1000pF capacitor and ended up with 4T on a T106-2 core....
By expanding or compressing the inductor the efficiency changes.....
Just like Steve QIX output tuning .... adjusting for lower current while the voltage and power remain the same....

200 watts on 40M is a nice power level...

I will stick to my H Bridge TXs....


Wayne




* 40M PP output.JPG (470.05 KB, 1600x1200 - viewed 346 times.)
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M0VRF
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« Reply #10 on: January 14, 2021, 03:41:06 AM »

Nice one Wayne, yes the same as mine now. Adjusting the L changes the match and can be for max power or max efficiency depending on your needs.

I'd be most interested to see your H bridge design, is it even simpler and more efficient than this design?

Regards.

JB.
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vk3alk
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« Reply #11 on: January 14, 2021, 05:08:49 AM »

Actually all my transmitters are H Bridge......
They are just switches ... no resonance anywhere apart from the 40M one I use.....
I am making another 40M module that uses 2 H Bridges into a combiner like my 160/80M transmitters....
Have only just started and will post the outcome probably in about 4 weeks or so all going well ....


Wayne
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M0VRF
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« Reply #12 on: January 14, 2021, 06:12:55 AM »

Nice one, please lets keep this thread going, I'm not a fan of valves (sorry y'all!) at all and as there's such great devices around now its a good time to investigate and develop new designs that are highly efficient and relitively simple to produce.

Best Regards from the UK.

JB.
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KF1Z
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Are FETs supposed to glow like that?


« Reply #13 on: January 14, 2021, 06:53:17 PM »

Wayne...
I wonder if I could ask you to post the schematics and good values for this ?

I am trying to find some 40m info and cant seem to find some
( I miss the old monkey-puppet forum :-) )

Thanks

Bruce
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vk3alk
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« Reply #14 on: January 14, 2021, 09:32:49 PM »

No problems at all Bruce....

Not sure how to link to a post from Nigel VE3ELQ but copied the link and pasted it below ..

http://amfone.net/Amforum/index.php?topic=38308.0

If you search for VE3ELQ the post is down the bottom of the page and has the circuit diagram there etc:
The FETs I used are CREE C3M0280090 ......

If you need help winding the transformer can upload pictures too .....
My component outlay was just experimental but worked OK... but would copy Nigel's method more and keep the tracks as short as possible.

The old monkey-puppet forum has totally gone now.... cannot remember why it ended  Shocked

There is a lot of things to make really...
Nigel has a 20M class E there too...
The bands appear to be improving so will give that a try later this year.....
Who knows I maybe able to work you guys  Grin


Wayne


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KF1Z
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Are FETs supposed to glow like that?


« Reply #15 on: January 15, 2021, 08:46:38 AM »

Thanks Wayne...
Guess I'm just blind.
I skimmed down through that thread yesterday and didnt see Nigels pdf  :-)
Found it now though... thanks
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vk3alk
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« Reply #16 on: January 15, 2021, 08:42:34 PM »

Just some final thoughts on this Transmitter....
I'm not an engineer just a Ham like most of us here.....

If 10 people made this TX with our different building technics no results would be the same ....

This design using the LPF is a compromise between the hulky output tuning of Class E and lower efficiency for smaller size ...

But it does work after some tinkering and mucking around....

The output transformer has to be made well using thick wire no less than 1.8mm for the primary and I used larger multi stand wire for the secondary and 2 cores T200-2 ..... cable ties like what JH used are a good idea pulling them together ...
Check the drain waveforms are equal and at the output of the transformer a sinewave looking waveform should result....

The series circuit using appox 1000pF Capacitor and 4 turns on a T106-2 core is experimental and is a low Q circuit so a dip will never be found....
But by squeezing or expanding the turns will result in a change of TX current and what your after is a lower current for same RF output power...  

Efficiency from say 88% or more is great  Smiley

Thats all....


Wayne
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M0VRF
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« Reply #17 on: January 16, 2021, 06:29:06 AM »

OK, as a few folk have PM'd me.....

I'm happy to supply part built (ALL SMT parts fitted) PCB's.

I'll need to know the frequencies you intend to use as the design uses a preprogrammed PIC to control the AD9850 DDS and I'll have to program in the frequencies (DIP SW selectable, a rotary front panel control can of course be added by the constructor)

You'll just have to supply your own toroids 2 x T200-2's and 3 x T106-2's (change these to -1's if for 160m or 80m) and 4 x CREE SiC FETs. Plus the Drain caps, series tuning and LPF caps, these are available from Farnell.

These VISHAY 2KV jobbies are nice...

40m Drain caps 2420175
160m Drain caps 2906248

FETs

40m = C3M0280090D
80m = C3M0065090D
160M = C3M0060065D

I can provide full instructions, waveforms to look for, CAD data to mount the PCB to a heatsink and everything you may need.

For the 200W design you're going to need 96V (2 x 48V 10A smpsu's in series)

For the 100W design a single 48V 10A smpsu.

Credit to Nigel for 'Modernising' the design and Steve or course for coming up with all the info in the first place.

Having a PCB makes this a fairly simple and repeatable affair.

Regards to All.

JohnB.
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km6sn
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« Reply #18 on: January 27, 2021, 12:36:27 AM »

Wayne, yes a separate thread would be nice.
Rod KM6SN
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vk3alk
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« Reply #19 on: January 27, 2021, 03:33:23 AM »

Ok will start a new thread soon...
Are not far off finishing hopefully  Grin

Have ordered some parts to build Nigel's 20M Transmitter .......

If anyone wants to beat me to it I don't mind  Smiley

Nigel's 20M Transmitter is a good thread name ......


Wayne
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M0VRF
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« Reply #20 on: January 27, 2021, 07:04:09 AM »

I built it as soon as it was posted and can confirm it works fine at 14MHz. Those GaNs are good!

J.
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vk3alk
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« Reply #21 on: January 29, 2021, 01:07:11 AM »

Well have definitely finished with this transmitter.....

Replaced the inductor wound on a T106-2 core with an air inductor ..... 4 turns on a 3/4 inch former ....
No reason just that an air coil is easier for me anyway to expand and compress  Grin

55 volts at 4 amps delivered 207 Watts.
93% sounds good efficiency  Smiley  but the main thing is it produced good power ( my dummy load told me that ) and all components were cool etc:

So for the people out there who want to build their own it's doable and a worthwhile effort ......

Will give people a rest from my posts as are waiting for parts to arrive  Grin

Just one final thing .....
Most of the transmitters I experiment with I reuse the parts or take them apart etc:
But this TX as well as Rods 75M one work well and will remain complete waiting maybe for use on air who knows ...


Wayne


* 40M Nigel finished for good.JPG (473.38 KB, 1600x1200 - viewed 354 times.)
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W1IA
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WWW
« Reply #22 on: March 04, 2021, 02:22:04 PM »



Pat, can you fill me in on your PDM design? Very intersting. Steve WA1QIX isn't going to make a board order for some time. I was able to repair and old board I had and may use that in the next build.

Thanks Brent W1IA

Wayne

Looks great.

I have been making some PC boards and hope my shop will be complete in two weeks. I have a design done for two FETs for a low power rig to drive an amplifier using Nigels circuit and the transformer that you are using. I also have redone my board for his PWM circuit . I have added a divide by two splitter and two regulated power supplies on board.

Seems like the shop area is taking way longer  than I hoped. The two work cabinets with drawers are holding things up.

Pat
N4LTA
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M0VRF
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« Reply #23 on: March 04, 2021, 02:32:05 PM »

I've got PWM PCBs.

Thought I'd already posted up the design?

'Board for Nigel's PWM Power Circuit' post

They're SMT however..

JB.
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vk3alk
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« Reply #24 on: March 04, 2021, 04:28:41 PM »

Hi Brent...

I have one of Steves QIX generator and output boards that I will no longer use again....
Not sure of the version but has the 2 output levels 12 and 5 volts....
They both work fine....

I did send them to Jon KA1TDQ in California but he moved and the postal department didn't forward them to his new address and returned them back to me..... Cry

Jon doesn't come on the forum anymore which is a shame  Sad

Not after any money .....
If you need them for another build your welcome to them .....

Just send your mailing address via email if you want...


Wayne


* P1030337.JPG (463.27 KB, 1600x1200 - viewed 230 times.)
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