[time-nuts] HP58504A antenna

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Jul 21 19:00:53 EDT 2008

WB6BNQ wrote:
> Hi Jose,
> If you trace out the power feed (the bottom direction from the coax connection) it supplies the transistor (most likely a MMIC) and the black 6 legged active device (no idea on it).  The silver square looks like a filter
> device of some sort between what you call the transistor and the 6 legged active device.  The silver square has no voltage going to it.
> The 30 milliamps does not sound out of range to me, but then I have no experience with the hp system.  What makes you think it is the antenna that is the problem ?  If the voltages appear to be about right (your
> statement) my guess would be that the antenna might be working correctly.
> So I would not be shorting anything out without getting a lot more information first.  Is there anyone else in your area that has such a system that you could compare with ?
> Good luck,
> 73....Bill....WB6BNQ
> Jose Manuel wrote:
Actually the 4 leaded input device is more likely to be a depletion mode 
FET (not Si but GaAs, or other III-V semiconductor) with the gate 
connected to ground via the .
The 2 wide leads are both source connections.

The 6 leaded device is likely to be a MMIC.

Try an old HP semiconductor  (or an Avago) catalog for likely candidates.


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