[INRAD] Pin Diodes

Sat Nov 26 12:33:44 CST 2005

Hi Bill and Charlie,

interesting discussion.

Philips has or had a nice AM PIN diode used for RF
attenuators with low distortion for frequencies above
100kHz.
It is the BAQ800. Probably OK up to around 1MHz as the
Rs is dropping as the ferquency is increasing
For If = 10mA charge carrier time = 10 to 20 uS and R
= 5 to 10 ohm.

Infineon (ex Siemens) has PIN diodes BAR14-16 with a
carrier time not too high: 700 to 1000 nS.

Some people have used BA244 Si Planar Switching diodes
R= 0.4 - 0.5 ohm found in FM and TV tuners to replace
switching diodes in Jap Black Boxes but these seem not
so good versus PIN diodes (??). Maybe the If current
was too low.

73

Gian
I7SWX

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> Today's Topics:
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>    1. Re: Switching diodes in roofing filter for the
> IC-775DSP
>       (William E. Sabin)
>    2. Re: Switching diodes in roofing filter for the
> IC-775DSP (Thomas)
>    3. Re: Switching diodes in roofing filter for the
> IC-775DSP
>       (Charlie Mazoch Jr.)
> 
> 
>
----------------------------------------------------------------------
> 
> Message: 1
> Date: Fri, 25 Nov 2005 17:15:15 -0600
> From: "William E. Sabin" <w.sabin at mchsi.com>
> Subject: Re: [INRAD] Switching diodes in roofing
> filter for the
> 	IC-775DSP
> To: "Thomas" <ac7a at cox.net>,	"Charlie Mazoch Jr."
> 	<w5vin at earthlink.net>
> Cc: list at inrad.net
> Message-ID:
> <000801c5f216$1849cfe0$6402a8c0 at DBYKXS51>
> Content-Type: text/plain; format=flowed;
> charset="iso-8859-1";
> 	reply-type=original
> 
> The MPN3404 has a recombination time of  "a Few
> Microseconds" and the 
> HP5082-3081 has "2500ns = 2.5 microsec".  These two
> types appear to be 
> almost identical in that respect.
> 
> Bill W0IYH
> 
> ----- Original Message ----- 
> From: "Thomas" <ac7a at cox.net>
> To: "Charlie Mazoch Jr." <w5vin at earthlink.net>
> Cc: <list at inrad.net>
> Sent: Friday, November 25, 2005 10:50 AM
> Subject: Re: [INRAD] Switching diodes in roofing
> filter for the IC-775DSP
> 
> 
> >
> > The mistake that many hams make is assuming that
> any PIN diode will work
> > in most any application. The MPN3404 is rated for
> VHF switching
> > applications, because its recombination time is
> short; a few
> > microseconds. Yet, I often see the MPN 3404 used
> in HF RF and IF
> > applicaitions. Not to say that it won't act as an
> RF switch, but it will
> > not provide the isolation or low distortion of a
> more suitable HF PIN
> > device. By a more suitable HF PIN device, I
> suggest a device like the
> > HP5082-3081, with its 2500nS recombination time (1
> tau).
> >
> > 
> 
> 
> 
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Fri, 25 Nov 2005 17:44:39 -0700
> From: Thomas <ac7a at cox.net>
> Subject: Re: [INRAD] Switching diodes in roofing
> filter for the
> 	IC-775DSP
> To: "William E. Sabin" <w.sabin at mchsi.com>
> Cc: list at inrad.net
> Message-ID: <4387AFF7.9040109 at cox.net>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> 
> William,
> 
> You have a valid point and I did make a mistake
> regarding the MPN3404 
> recombination time. I have the HP spec sheet for the
> 5082-3081 and it is 
> indeed 2.5us. However, my Motorola MPN3404 data
> sheet does not list the 
> recombination time and I made the incorrect
> assumption that it was 
> microseconds - which on second thought can't be
> correct. The data sheet 
> says that it is intended for VHF switching
> applications which implies 
> that its recombination time must be much less than a
> microsecond.
> 
> My lame excuse for the error is I was being hurried
> to head out the door 
> while I was typing my response to Charlie's email.
> You know when the XYL 
> is saying let's go... it is time to go!
> 
> '73, Thomas - AC7A
> 
> 
> William E. Sabin wrote:
> 
> > The MPN3404 has a recombination time of  "a Few
> Microseconds" and the 
> > HP5082-3081 has "2500ns = 2.5 microsec".  These
> two types appear to be 
> > almost identical in that respect.
> >
> > Bill W0IYH
> >
> > ----- Original Message ----- From: "Thomas"
> <ac7a at cox.net>
> > To: "Charlie Mazoch Jr." <w5vin at earthlink.net>
> > Cc: <list at inrad.net>
> > Sent: Friday, November 25, 2005 10:50 AM
> > Subject: Re: [INRAD] Switching diodes in roofing
> filter for the IC-775DSP
> >
> >
> >>
> >> The mistake that many hams make is assuming that
> any PIN diode will work
> >> in most any application. The MPN3404 is rated for
> VHF switching
> >> applications, because its recombination time is
> short; a few
> >> microseconds. Yet, I often see the MPN 3404 used
> in HF RF and IF
> >> applicaitions. Not to say that it won't act as an
> RF switch, but it will
> >> not provide the isolation or low distortion of a
> more suitable HF PIN
> >> device. By a more suitable HF PIN device, I
> suggest a device like the
> >> HP5082-3081, with its 2500nS recombination time
> (1 tau).
> >>
> >>
> >
> >
> >
> 
> 
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Fri, 25 Nov 2005 18:53:20 -0600
> From: "Charlie Mazoch Jr." <w5vin at earthlink.net>
> Subject: Re: [INRAD] Switching diodes in roofing
> filter for the
> 	IC-775DSP
> To: "William E. Sabin" <w.sabin at mchsi.com>, 
> list at inrad.net
> Message-ID: <4387B200.40404 at earthlink.net>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> 
> Hi Bill:
>  Here is a wonderful article on PIN and PN diodes. I
> learned the fact 
> that current flow consists of only majority carriers
> in the Schottky 
> diode.   Interesting.   73's   Charlie
> 
> http://www.microsemi.com/idx.asp?MN=435
> 
> 
>   William E. Sabin wrote:
> 
> > The MPN3404 has a recombination time of  "a Few
> Microseconds" 
=== message truncated ===

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