150 watt 23cm amplifier

[VK3WRE]

Hi All, I have been playing at using cell phone LDMOS fets at 23 cm. After much work I have built 2 prototype amps that work well.

The design is based on a couple of designs  from Europe and is on Rogers 4003C board.

The results so far.   1.5 watts of drive produces 150 to 160 watts and out saturated at about 170 watts with a bit more drive.

Running the amp at 28 volts produces good gain and output power at about 9 amps. note the gain is 20 dB !!

Its very pleasing to get good results from a project. 

cheers Ralph VK3WRE

[VK2JDS]

Hi Ralph, looking really good there !
The ldmos is soldered to a copper spreader by the looks of it.
Im hoping you will elaborate on your build pictures, pcb availability, circuit and dimensions as we are all really interested in getting reliable high power on 23cm.
73 Dave

[VK3QI]

Ralph and Dave,

I recently took delivery of a 1296 amp from Ukraine which uses the Freescale MRFE6S9160HS device.

(I couldn't resist buying it to compare with my 8 x MRF286 amp!)

Full details of the amp including test results can be found here:  http://vhfdesign.com/en/pa/pa-23cm-1296-...-watt.html

They make some really nice pieces of equipment at quite reasonable  prices.


Cheers

Peter  VK3QI

[VK2ZIW]

Hi Ralph,
How did you solder the "chip" onto the copper heat spreader?

Those transistors MRFE6S9160HS are but $12 each bare, no heat spreader!!

I've ordered six.

Alan VK2ZIW

[VK3WRE]

Hi Ralph,
How did you solder the "chip" onto the copper heat spreader?

Those transistors MRFE6S9160HS are but $12 each bare, no heat spreader!!

I've ordered six.

Alan VK2ZIW

Hi Alan, I just use an aluminium plate on my gas stove with the copper heat spreader on top. 
On a low heat I wait until a bit of solder just starts to melt then I put the device down on the solder.
I then remove the heat once the device has settled, slow cool down is probably the key to survival of the device.
I would recommend low melting point solder paste but I dont have any yet.
So far I have done 4 of the MRFE6S9160 devices and numerous other MRF9070 devices without any failures. 


Ralph VK3WRE

[VK2ZIW]

Thanks Ralph,

Because I don't have any 0.7mm teflon PCB, and no caps either,
But I do have 1.5mm teflon PCB 400mm x 60mm with one heavy track
making a 100MHz three way splitter,, now free.
A lot of the caps are less than 5pf which is very achievable with small tabs, mica compression style.
Your Rogers PCB, looking at the output matching, makes a transmission line of about 5 ohms.
Bottom line:: Has anybody any software design tools to do a simulation?
Alan VK2ZIW