[time-nuts] HP58504A antenna
ch at murgatroid.com
Tue Jul 22 00:32:05 EDT 2008
> I?d like to repair a HP58504A antenna that don?t deliver any output
> signal. The current is about 30 mA ( I think too high), and the
> transistor (unknown type) and the MMIC (uPC2749TB), seems to be with
> correct voltage.
> Does anyone have any experience or data about this antenna?
> I took an inside photo: http://www.ea1px.es/HP58504A.jpg Can the
> transistor be identified by the color code?
I'm assuming correctly that the big blob of solder in the LL
is the antenna connection, otherwise please ignore all of this.
I suspect that "transistor" is really an MMIC in one of the
fancier packages rather than a discrete transistor.
It looks to me as if the bias flows through the trace on the BR
and then through a couple of 001 R's before the bias
setting 221 R.
This MMIC is before the filter, so it is probably been selected
and biased to avoid IM problems.
But I don't think 30 mA sounds too high.
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