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I need POWER COMBINER/DEVIDER for 500W FM Broadcast

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pioneer_007

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fm combiner pcb

I would like buil 500W power amplifier. I have 2 stand alone boards with MRF151G - 300W each. I need some power devider and power spliter design.

regards,
pioneer 007
 

nandopg

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how to make, power divider, fm broadcast

No doubt, the old Wilkinson is the best option in your case.
Build up the splitter and combiner using good quality Teflon coax cables. For the output combiner choose a Teflon coax cable rated for an average power grater than 500Watts.
Don't forget to use cables with the same length to connect the splitter and combiner to the amplifiers.
The isolation load for the combiner should be rated for 125W, so that to have some margin 200Watts would be desirable.

Hope this help you.

NandoPG
 

pioneer_007

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fm power combiner

Hi NandoPG ,
thank you for your replay, i need PCB type combiner. I know that the Willkinson is faster way to resolve the problem, but i need PCB type. I have some combiners from FM AMPLIFIER EKA500 from Elettronika, I have grafix of the boards, but material is unknown. I would like to use similiar combiner. Can you offer me some PCB power combiner for 2 x 300Watts ?
 

pioneer_007

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fm 500w amplifier

Hi NandoPG ,
thank you for your replay, i need PCB type combiner. I know that the Willkinson is faster way to resolve the problem, but i need PCB type. I have some combiners from FM AMPLIFIER EKA500 from Elettronika, I have grafix of the boards, but material is unknown. I would like to use similiar combiner. Can you offer me some PCB power combiner for 2 x 300Watts ?
 

nandopg

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power divider broadcast fm

I sent a PM to you. If you have additional questions, just let me know.

NandoPG
 

yingyang

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fm power combiners

hI GUY,
pLEASE LOOK AT A recent PAPER IN THE ieee transactions on microwave theory and techniques on "broadbanding an inphase power divider".
Hope this help.......


:lol: :lol: :lol:
 

yingyang

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mrf151g

You can also look at the recent active distributed transformer for this kind of power combining and dividing.


Hope this help.....

:lol: :lol: :p :p :lol: :lol:
 

flatulent

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combiner fm

The suggestion for using the wilkins is easily the best. You can use 70 Ohm coax RG/59 or RG/11. You put them in a metal box with coax connectors and the resistor between the two inputs as described above. Put coax connectors on your amplifier boards which the probably alread have. This can fit inside the transmitter cabinet and no one will see it. The coax cables can be wound around inside the box to make it smaller. You use a coax T connector to connect the two ends at the 50 Ohm port.

If you insist on microstrip, here is a design program in which you can select the substrate material and it will give you the dimensions of the line along with the wavelength in the transmission line. You can use this to determine the quarter wave length.
 

nandopg

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500w fm amplifier

Dear friends:
In order to design properly a Wilkinson microstrip power combiner/splitter some guidelines should be followed:

1- The thickness of the dielectric material should be chosen so that the 75 ohms microstrip line's width that makes up the Wilkinson is rated for the full operating power.

2- The dielectric constant should be low.

3- The dielectric isolation of the substrate should be rated for the peek voltage will be flowing across it.

Regarding all of this:
A Teflon based substrate is the best choose.
For 500Watts power output a dielectric thickness about 0.15 inches should be used.
Don't forget to use a 125 Watts, 100 Ohms isolation100 load.

If you follow this guideline for sure you will have a happy end.

Regards,

NandoPG
 

markken

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Hello poineer 007. I have been building MRF151/141G amps for many years for FM broadcast, but only this year have I taken on the wilkinson. I have a PCB stripline combiner designed for 157 MHz from a Pager tx, so i went about using this at 144 MHz. ( ham band). I had to cut each side of the tracks and add some L to get the efficiency good for 144 Mhz, but all in all a good outcome.

As the current long haul DX is not good for 144 at present, I have removed the output combiner for 144 MHz, and fitted a coax one for the 6m 50MHz ham band, now the same amp will deliver 600 watts at that freq, I have made many 2000klm plus contacts between New Zealand and Austrailia, and a hand full of 6000k contacts to Perth in WA.
I wish I had mastered the wilkinson a long time ago.
My latest project which is nearing completion is 2x 500 w TV PAs for 1Kw on 50 MHz.

I would be keen to know how you got on with the 500 w FM pa project, I realise that it was a few years ago.
Also any one else that has build PAs in the 500-2kw area using transistors of FETs id be keen to hear from as well.

73.
Mark.
***markken@xtra.co.nz***
 

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