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Author Topic: yaesu FT-7  (Read 1225 times)
BIKRRIC
Member

Posts: 2




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« on: February 23, 2010, 08:29:53 PM »

Just got a ft-7 and when you power it up it draws 3 amps and rises the longer you have it on. No rx out of speaker. I was told the previous owner reversed the power cables.I found a diode at the power  plug melted and replaced it,amp draw  still climbing and tx amp heat sink getting hot. Any help would be greatly appreciated. thanks in advance.73s

Rick
RC9RJW
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BIKRRIC
Member

Posts: 2




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« Reply #1 on: February 23, 2010, 08:37:31 PM »

Sorry for the mistake my call sign is KC9RJW not rc9rjw not very good at typing
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WB6BYU
Member

Posts: 17484




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« Reply #2 on: February 23, 2010, 09:18:17 PM »

The heat sink getting hot sounds like the output transistors are turning on -
either because they were damaged, or because some other part of the
bias circuit is damaged.  I don't remember the innards of that radio but see
if there is a wire running the +12V to the final amplifier module that you can
disconnect.

Once you have that handled you can see about troubleshooting the receiver,
though there may be other damage throughout the rig.  Start at the audio
output stage and see if touching a screwdriver blade to the input of the
audio amp causes any noise in the speaker.  Continuing working backwards
through the receiver one stage at a time to confirm they are in operating
condition.   When you have the receiver working (including the VFO, since
the receiver won't work without it) then you can check the low power
transmitter stages up to the final amplifier.  Eventually you'll have to get
that working, too, which may require replacing the final transistors.

But the final transistors are likely to be the most expensive part, and there
is no need to buy new ones if you can't get the receiver to work.
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K7UNZ
Member

Posts: 691




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« Reply #3 on: February 24, 2010, 04:04:05 PM »

Sounds to me like it might possibly be "stuck" in transmit....drawing power, heat sink warming, no receive.

Have you had it on a dummy load, with a power meter, to see if it has a transmit output?

Jim/k7unz
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