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follow-up: GaAsFET part help



Last week I wrote regarding my dysfunctional Mirage mast-mount preamp,
and mentioned in passing my dysfunctional TE Systems preamp that uses
the same active device.

Thanks for all for your (many!) replies.

Some observations etc., which may prove largely known but might help
someone someday (?):

1. If something uses open-frame relays, invest in a good contact
burnishing tool!  The TE Systems preamp has a 5A open-frame relay
(Guardian Electrical Systems type 1365) that just needed a good
cleaning.  

1a.  I've always wondered...how do we/manufacturers "get away" with
using generic power relays like that for RF (even VHF) applications? 
How would one translate "power" ratings to RF?  There surely is some
performance tradeoff between cheap(er) power relays and going coaxial. 
The Mirage preamps at least use an RF-rated Aromat relay, but it appears
from the ratings to be a small-signal device (I think 10mA contact
rating)...100W in 50ohms is much more than 10 mils!

2. Even my old 1992 NEC catalogs don't have the NE25337 device listed. 
NEC nomenclature generally is NExxxyy where xxx is the die type and yy
the package; there's not a single xxx37 package shown anywhere I can
find.  Oddly enough, I have some NE25337-D devices which are the old
"Macro-X" package...perhaps nomenclature wasn't quite solidified back
then.  Presumably the same performance but a plastic pill.  Also have
some NE25339 which are SOT packaged.  Of course, neither package can be
easily retrofitted in for the itty bitty package used in either preamp
:-( but at least I can build my own.

3. Turns out that my particular Mirage preamp uses a small toroidal
transformer with 11-mil magnet wire at the output of the two active
devices (the second being a U309 in common-gate).  It makes a wonderful
fuse--mine was open at a winding junction, thus preventing full drain
bias from making it to the U309.  So...looks like no active devices
needed, after all.  

4. The bias-tee that Mirage supplies with their mast-mount units is an
interesting beast.  There's actually quite a bit of active electronics
in it, not just a series-C/shunt-L configuration.  I'd be interested in
anyone's comments/experiences regarding bias-tee's in general, since a
search of my literature (HR, QST, QEX, 'net) showed absolutely zero
"design" information.  Too simple a device?  

Enough rambling for today, best save some for tomorrow,
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