[hpsdr] Quick and clean final for Penny

[FRANCIS CARCIA]

Hi,
I picked up a final strip out of an MRI system and modified it to work on HF. I saw this 3 stage amp on ebay made by Erbteck with push pull MRF150s in the output stage. I changed out a few driver transformers with type 43 cores (5) and added turns to the final shunt choke and output transformer windings. Also bypassed all the digital bias control and installed pots off an internal regulator to set the operating bias. I presently have the strip working down to about 1 MHz with 30 volts on the driver and final so it should work fine on 160 when I go to full voltage of around 48 volts. The first stage runs on 24 volts and set up for class A. I can't go to full voltage until I mount the board on a bigger heat sink. Penny has no problem driving the first push pull stage so the big CATV amp isn't required. I have been able to get some real clean IMD numbers at low power and high bias current. I plan to saw the board in half to eliminate all the old MRI bias
 and attenuation control. Then mount the strip with a little bias circuit on a nice heat sink. This would run at about 300 watts with IMD in the 30s or better at reduced power and class A operation. The output can be fed into Alex and might need a little control to kill the bias in RX. 
I was lucky to find another Erbteck board with 4 push pull MRF150 stages which I hope to modify to be a linear.
I can provide the modifications to anyone interested. This was set up for 60 MHz so a number of .01 caps need to have .1 uf in parallel. Not a bad deal for $60.
I've had good on air tests on 160M SSB and AM
Frank WA1GFZ
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