Hi Stefano...

It's true what Bear states about Push Pull but the circuit you provided is exactly what I do for 40M...and other bands...
Two separate H-Bridge modules feed in Single Phase with the outputs both having to see 25R connected as an adder to 50R...
So if you wanted to connect 3 other Groups of 2 totalling 8 you just continue the secondary along....
But be careful when feeding the wire not to get the phasing mixed up as cancellation will occur etc:..
You would have to change the turns ratio of the output transformer to 1:1 so that each H Bridge will see 6.25R though...
For 500Watts appox just one group of 2 should get close if all going well...
Your output transformer .... if those 2 cores are type 43 will get hot when modulation is applied...

Wayne

Wayne,

Some people including me as getting older don't like high voltages. With 50V switching supply, 40% duty cycle (20V carrier level) you can achieve 150% assymetry modulation with 8 modules in series for about 500W carrier. It works like harm without ventilation.
The schematic is like the one in the attachment multiplied by any number.


Bear,

Hmmmm that's why almost everywhere are used both phases. It is the push pull even harmonic reduction benefit.
A 7th order Butterworth LPF instead of the usual 5th order could also help however in this part.


 

Assuming that 1/2 the drive is out of phase by exactly 180deg with the other, and then sent to separate modules,
and wired as Push-Pull, then there is significant reduction in even order harmonics...

                       _-_-bear

Thursday evening I worked a few 6M CW aurora contacts from MA. Band was active.
Friday afternoon there was a 6M opening to South America. Worked 4 countries on SSB. Lots of fun on 6M.

Jerry W1ZB

this post was started in 2005.

I have never added 8 modules only 2 but the same principal exists I would say......

Can I ask why your using so many modules and what output carrier power you are hoping for....
Also can you supply the circuit diagram and what FETs they are....as well as the band of operation...
I'm just a little concerned about the distances between your modules for the secondary winding but I suppose time will tell...
Have you tested the modules and are you happy with their proformance etc:


Wayne

Hi Wayne,

It is exactly as you described it, adders. Of course your support helps me to decide the final design.
From the DDS square wave output, 8 same length cables will feed the single phase to the inputs of 8 drivers (IXDD614CI).
PCBs and supplies on hand. Looking only for DDS, power/swr meter with swr and temperature protection.
No final decision though for mosfets, I'll expect your suggestion.
Thank you.

Stefano

Mike,
I may have one. Let me check the junk box this weekend. Feel free to bug me.

Thanks Steve.

The ssb contacts came in waves. I'd get 8 to 10 in a row then everything would go silent for a while. CW did the same but not as much. Everyone I heard on cw I worked. Created a few mini pileups with a CQ now n' then.

Will be looking for you on 40M this winter!

Buddly

In case you havn’t seen it, Dacw W7UUU posted this stuff available dirt cheap on QRZ. Everything is apparently hugely negotiable. Pick up face-to-face only.
I’m looking for an S-200 speaker like they have but figure it will cost $900 for gas so I decided to pass.

https://forums.qrz.com/index.php?threads/large-lot-boatanchors-hammarlund-hallicrafters-national-heathkit-henry-eico.931511/#post-6975592

https://forums.qrz.com/index.php?threads/save-them-from-being-parted-out.932038/#post-6980093