Author Topic: YAESU FT100 repair of Local-Unit board  (Read 331 times)

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Offline rjj100

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YAESU FT100 repair of Local-Unit board
« on: March 25, 2019, 02:33:59 am »
I could use some help. The LO output on my FT100 is 94 mv p-p not 2.2v p-p into 50 ohm (11dbm) on 145 Mhz. The VCO is working, but I sometimes lose lock and the power output is about 1/2 w. on 2 m and 1-1/4 m.

There are various filters and switching circuits but the schematic or manual does not identify which path is used on 2 m and 1-1/4 m. It would be helpful to know the rf voltmeter measurements on 2 and 1-1/4 m on this board. Can anyone help? NQ5P


Offline rjj100

  • Newbie
  • Posts: 2
Re: YAESU FT100 repair of Local-Unit board
« Reply #1 on: March 27, 2019, 04:09:05 am »
There is a lot of solder resin on this board, so I am going to clean it off best I can with denatured alchohol and then dry it well before preceding.

I made a measurements after the first stage (Q2014 emitter), but it looks like there is no 9 volts powering the Q2031. Wondering if that is right on 146mhz on receive. It looks like any of the following signals could turn turn on the 9 volts .... BP, H1, H2, H3.  What do these mean?

If the 146 mhz signal doesnt go thru Q2031, then does it go thru d2054 and d2031?

I really could use a good description of the functions and switching on this board.

Aside, It is extremely difficult to read the board layout much less find the probe position on the board itself.  :rant:

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