[hpsdr] Front End protection

[Larry Taft]

FRANCIS CARCIA wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
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> I don't know which Greek God guarded the gate but how are we going to 
> protect this fast A/D from static and lightning transients? Racal used 
> an interesting active limiter ahead of the RA6830 because the older 
> RA6790 had real bad burnout problems with the FETs in the first mixer. 
> I would think we need more than a NE2 across the input.  Frank WA1GFZ
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Drake used a small gas tube across the TR-7 input along with a RF 
choke.  The weak link in the TR-7 is the PIN diode that switches the 
calibrator signal into the receiver front end.  The first mixer seems to 
hold up quite well.  Of course the schematic doesn't show the parts or 
the values but I can find them.  They were a field fix.

73, Larry K2LT

 1172123058.0