[time-nuts] Adding prescaler to HP 5334B
Robert Berg
bob.b at pobox.com
Tue Apr 1 15:46:16 UTC 2008
Bruce,
Thanks for the ideas. The HSMS-2822 looks like it could serve in the
detector role, while a pair of HSMP-3822's might work for clamping--low
capacitance, matched pair in series, and in stock at Mouser. The 3822 is
actually a pair of PIN switch diodes, but couldn't it function as a clamper?
The 482x series looks better for clamping, but isn't available in a
series-pair configuration. There are other possibilities, but not many in
stock, and I couldn't find any suitable ring diode packages.
Bob
WA7ZRX
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Monday, March 31, 2008 6:37 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Adding prescaler to HP 5334B
Bruce Griffiths wrote:
...
> Not particularly critical as they are only used as clamps to limit the
> input signal to the 30dB gain preamplifier.
> You may be able to use a single pair instead, albeit with a lower input
> damage level.
> Using a quad allows the clamp current to be shared between a pair of
> diodes, however some matching is required to ensure effective current
> sharing.
> Too much diode shunt capacitance will limit the bandwidth.
>
> Bruce
>
Quad CR303 acts as a clamp, Quad CR302 acts as a detector with
temperature compensation.
Only 2 diodes in CR302 are used so CR302 can be replaced by a matched pair.
Try using low barrier microwave specified schottky diodes with lower
capacitance than a 1N5711.
Bruce
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