Envelope-to: dave@picks.force9.co.uk
Delivery-date: Tue, 22 Nov 2005 15:18:46 +0000
From: "james moritz" <j.r.moritz@herts.ac.uk>
To: rsgb_lf_group@blacksheep.org
Date: Tue, 22 Nov 2005 15:17:20 -0000
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Subject: LF: RE: BYX10 as  LF PIN diode
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Dear Bob, LF Group,

If you have not already seen it, there is a PIN diode handbook available as
a pdf file from Microsemi corporation:

http://www.microsemi.com/literature/pinhandbook.pdf

This is quite informative. There is also a much shorter application note:

http://www.microsemi.com/micnotes/701.pdf

Microsemi make PIN diodes for high-power HF applications; the app notes
suggests they might work well at lower frequency too.

I believe high voltage rectifier diodes often work quite well as PIN diodes
because they also use the PIN structure to increase the breakdown voltage.
The thing you have to be wary of when using devices in an un-intended way
like this is that diodes marked "BYX10" and made by different manufacturers,
or the same manufacturer at different times, may use different processing to
achieve the same performance as a rectifier. This means they will all meet
their rectifier specifications, but since the RF PIN behaviour is not
specified or tested, they may vary a lot in performance as RF attenuators.
This is OK in amateur applications, where it is practical to individually
select the diodes for suitability.

Cheers, Jim Moritz
73 de M0BMU

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Vernall
Sent: 22 November 2005 01:03
To: rsgb_lf_group@blacksheep.org
Subject: LF: BYX10 as LF PIN diode

Hi all,

A brief report on some experiments to assess diodes as current controlled 
resistors (as per PIN diodes) at LF.  I'm wanting to develop an ALC circuit 
for a new LF transmitter and PIN diodes are quite good for gain control 
using an attenuator circuit.  It seems that PIN diodes need thick junctions 
to work properly at lower frequencies...