Thanks everyone. This has given me a lot of things to check as I further
investigate over the next few evenings. I'll let you know what I find.
> On Aug 5, 2017, at 3:07 PM, Charles Steinmetz <csteinm...@yandex.com> wrote:
> Arthur wrote:
>> I’d say it would be an MMIC amp similar to this device [Avago MGA-87563]
> If a chip similar to the Avago part Arthur referenced is what is installed,
> which seems plausible, the 0.749v on the RF input (Pin 3) is a fault and is
> caused by an external source of voltage (3.417v) imposed on the RF output
> (Pin 6) through the internal feedback resistor to Pin 3, attenuated by the
> gate resistor.
> Avago says this particular chip needs to have 0vDC at Pins 3 and 6, so if the
> connected parts would impose any DC voltage on those pins, external blocking
> capacitors must be used on Pins 3 and 6. You might check to see if there are
> blocking caps (at least at Pin 6), and if they are good. (Alternatively, the
> internal output capacitor from Pin 6 back to the output FET source may be
> Of course, don't expect a bad external cap to be the only other problem -- if
> it is bad, the 6-pin amp may well be bad, as well as whatever is connected to
> the other side of the cap.
> Best regards,
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