"R.van Trotsenburg" <[EMAIL PROTECTED]> made an utterence to the drakelist gang
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Hallo Rick,
I have had the same problem in my TR7. It was caused by a parasitic
oscillation of the dual gate FET Q702 in the 2nd mixer board. It was
resolved by inserting a small ferrite beat in the drain circuit of  the
FET. This does quiet down the FET, without effecting the rest of the
amplifiers performance.
The easy way to do this is by lifting the 68ohms resistor R712 at the drain
side of the board and slipping a small ferrite bead (3x3mm) over the wire
end and solder it back in the board. May be you have to use a new resistor
because the wire end can be a bit short in length.
After that the problem never appeared again in my TR7. In two other TR7's I
have done this modification for preventive reasons.
Let me know if you are successfull.

Rien PA0TRT
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