[time-nuts] HP58504A antenna

[christopher hoover]

Jose wrote:

> 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.

-ch