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Replacing the PA section on Bitx 40

James Lawrie
 

Hello,

My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.

I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

Thanks,


James Lawrie

M Garza <mgarza896@...>
 

Why replace everything?  You can probably put it in place of the 510 (making sure it is pinned correctly, of course).  
I am waiting on a pair, myself, that I will be stuffing into the ubitx.   I want to even out the power output.  I will also try a resistor/capacitor in parallel, in series with the gate, to try and even out the frequency response.  I am thinking 4.7 ohm & 4700pf.  I will also try 6.8 ohm & 4700pf.  Depends on how flat I can get the output.

Marco - KG5PRT 

On Jan 31, 2018 10:12 PM, "James Lawrie" <lawriejk@...> wrote:
Hello,

My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.

I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

Thanks,


James Lawrie

 

Here is how I made the socket and mounted the RDD16

Note the RDD is reversed and  then the gate is actually soldered to the IRF gate line which goes behind the FET.
Now I can use either of them..

You will need to think of a heat sink plate that fits this way!

Emacs!


At 01/02/2018, you wrote:
Why replace everything?  You can probably put it in place of the 510 (making sure it is pinned correctly, of course). Â
I am waiting on a pair, myself, that I will be stuffing into the ubitx.   I want to even out the power output.  I will also try a resistor/capacitor in parallel, in series with the gate, to try and even out the frequency response.  I am thinking 4.7 ohm & 4700pf.  I will also try 6.8 ohm & 4700pf.  Depends on how flat I can get the output.

Marco - KG5PRTÂ

On Jan 31, 2018 10:12 PM, "James Lawrie" <lawriejk@...> wrote:
Hello,
My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.
I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

James Lawrie
 

My thought process is a separate board would allow more mounting options for a heat sink, and cleaner layout after on the Bitx 40. I hate to admit it but I’m not an engineer and even my basic math skills for electronics formula is severely restricted due to the “happy pills” I take for my service connected TBI and PTSD.

As a kid when I was trying to get into electronics and Ham I had a Elmer who helped, but now 41 years later I know no one else in my area who could/would help.I can follow schematics, and do basic - mid level troubleshooting, speaking of worse things I used to be very proficient in basic, pascal and early OOP programming, now thanks to my medical issues they are gone. I look a c and c++ and think it must be from Mars.

Probably TMI about myself but this is why I ask for help and like a clean board.

James Lawrie