On Oct 8, 2024, at 13:33, Michael Davis via groups.io <maddmd818@...> wrote:

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Thanks Ron. I wonder why the PAs fail. Hi SWR? Shorted coax? I read about the FETs going into self oscillation if internal battery is left in place. I also think I read that ND and 818 are better protected. Mine is new to me, non ND, almost brand new from an estate/SK? I'm using the LDG Z817 to minimize risk. Now to decide if I should get a PA board as a spare before they are gone.

73

Mike WA1MAD

On Oct 8, 2024 2:05 PM, "Ron Wright via groups.io" <lt_wright_flg@...> wrote:

I have replaced my 2004 FT817 PA twice.? Ordered the board from Yaesu and installed it.

I am EE and have done a lot of electronics although in work relied on techs to handly most of that.? Seems many dont like giving tools to EEs, but I have done most at home.

Replacing the PA is some what simple.? Do need to unsolder the old board and install including soldering the input and output coaxes to the board.? Then there is an alignment where you connect an Amp meter in the power line and adjust 2 pots, one for each PA transistor.? You will need a multi meter. There are good instructions on some of the FT817/8 boards.?

Dont be afraid of doing this.? Not like small surface mounted ICs.? Everything is rather large and easy to solder.

73, ron, n9ee/r

Ron Wright, N9EE/R

Hernando Co ARES EC

Spring Hill, Florida also n9ee55@...

On Monday, October 7, 2024 at 08:08:14 PM EDT, Ken N2VIP <ken@...> wrote:

That's great, thanks for sharing your success with us. I suspect you're right about saying it was for an FT-817.

Glad she's up and running, enjoy!

Ken, N2VIP

On Oct 7, 2024, at 18:59, Tech Guy <tech48055@...> wrote:

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It was easy. Desolder two small coax cables, power jumper, ground jumper and other ground. Tack solder a wire to the pad the positive jumper connected to and put a milliamp meter in line. Set the radio to 1.8 Mhz CW. I used a dummy load. Press ptt and adjust the pot on the right to about 42 ma when ptt pressed. Move to the left pot and adjust to about 82ma. Remove the wire and put the positive jumper back. I did add sone heatsink compound to the board before I screwed it to the heatsink. Look at the videos mentioned for details. I used to do tv repair years ago. This is much easier than pulling the smt fets that I couldn’t find anyway. Just be careful with heat and touching other pads or parts.