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1N5819s? Or just a couple of 1N4001s?

Started by Dave September 22, 2013
I have been wanting to make use of a pair of 1N5819s to protect an RF 
amplifier I am building from static discharge, should someone touch the 
antenna, but haven't been able to obtain any of these just yet. I DO have 
some 1N4001s however, and am honestly wondering what advantages the 1N5819s 
would have over the the more readily available 1N4001s (which are already 
sitting on my workbench.)  I have used 1N5819s in the past, and suspect I 
have forgotten something, I just can't remember what. What is it that I am 
missing here?  I believe I know what I ought to use, I just can't remember 
why.  Somebody, please, enlighten me, and refresh my failing memory.  What 
characteristic is it that the 1N5819 has that the 1N4001 so obviously lacks? 
I've looked at the datasheets, but it escapes me.  Many thanks for any 
advice, observations or measningful input.  I will probably wait for the 
1n5819s, I would just like to remember why...

Dave


On Sun, 22 Sep 2013 10:01:41 -0500, Dave wrote:

> I have been wanting to make use of a pair of 1N5819s to protect an RF > amplifier I am building from static discharge, should someone touch the > antenna, but haven't been able to obtain any of these just yet. I DO have > some 1N4001s however, and am honestly wondering what advantages the > 1N5819s would have over the the more readily available 1N4001s (which are > already sitting on my workbench.) I have used 1N5819s in the past, and > suspect I have forgotten something, I just can't remember what. What is it > that I am missing here? I believe I know what I ought to use, I just > can't remember why. Somebody, please, enlighten me, and refresh my > failing memory. What characteristic is it that the 1N5819 has that the > 1N4001 so obviously lacks? I've looked at the datasheets, but it escapes > me. Many thanks for any advice, observations or measningful input. I > will probably wait for the 1n5819s, I would just like to remember why... >
1N5819 is Schottky, 1N4001 is a junction diode. Chalk and cheese. 60 seconds with Google would tell you that. -- "Design is the reverse of analysis" (R.D. Middlebrook)
On 9/22/2013 11:01 AM, Dave wrote:
> I have been wanting to make use of a pair of 1N5819s to protect an RF > amplifier I am building from static discharge, should someone touch the > antenna, but haven't been able to obtain any of these just yet. I DO have > some 1N4001s however, and am honestly wondering what advantages the 1N5819s > would have over the the more readily available 1N4001s (which are already > sitting on my workbench.) I have used 1N5819s in the past, and suspect I > have forgotten something, I just can't remember what. What is it that I am > missing here? I believe I know what I ought to use, I just can't remember > why. Somebody, please, enlighten me, and refresh my failing memory. What > characteristic is it that the 1N5819 has that the 1N4001 so obviously lacks? > I've looked at the datasheets, but it escapes me. Many thanks for any > advice, observations or measningful input. I will probably wait for the > 1n5819s, I would just like to remember why... > > Dave > >
How about a nice transformer output? Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net

"Dave" <db5151@hotmail.com> wrote in message 
news:1v-dnd0jyaTKm6LPnZ2dnUVZ_qWdnZ2d@posted.internetamerica...
> I have been wanting to make use of a pair of 1N5819s to protect an RF > amplifier I am building from static discharge, should someone touch the > antenna, but haven't been able to obtain any of these just yet. I DO have > some 1N4001s however, and am honestly wondering what advantages the > 1N5819s would have over the the more readily available 1N4001s (which are > already sitting on my workbench.) I have used 1N5819s in the past, and > suspect I have forgotten something, I just can't remember what. What is it > that I am missing here? I believe I know what I ought to use, I just > can't remember why. Somebody, please, enlighten me, and refresh my > failing memory. What characteristic is it that the 1N5819 has that the > 1N4001 so obviously lacks? I've looked at the datasheets, but it escapes > me. Many thanks for any advice, observations or measningful input. I > will probably wait for the 1n5819s, I would just like to remember why... > > Dave
Shottky barrier diodes tend to have higher junction capacitance. Trr is very fast - but for this application you don't want them conducting if you can help it. If you are using an inverse-parallel pair - you don't need the higher voltage 5819, the lower voltage 5817 is more than enough. Unless something else clamps reverse voltage - shottky diodes themselves can be vulnerable to ESD. Shottky diodes have about 1/3 the Vf of regular silicon diodes.
"Ian Field" <gangprobing.alien@ntlworld.com> wrote in message 
news:wDJ%t.103664$kM7.92349@fx28.am4...
> > > "Dave" <db5151@hotmail.com> wrote in message > news:1v-dnd0jyaTKm6LPnZ2dnUVZ_qWdnZ2d@posted.internetamerica... >> I have been wanting to make use of a pair of 1N5819s to protect an RF >> amplifier I am building from static discharge, should someone touch the >> antenna, but haven't been able to obtain any of these just yet. I DO have >> some 1N4001s however, and am honestly wondering what advantages the >> 1N5819s would have over the the more readily available 1N4001s (which are >> already sitting on my workbench.) I have used 1N5819s in the past, and >> suspect I have forgotten something, I just can't remember what. What is >> it that I am missing here? I believe I know what I ought to use, I just >> can't remember why. Somebody, please, enlighten me, and refresh my >> failing memory. What characteristic is it that the 1N5819 has that the >> 1N4001 so obviously lacks? I've looked at the datasheets, but it escapes >> me. Many thanks for any advice, observations or measningful input. I >> will probably wait for the 1n5819s, I would just like to remember why... >> >> Dave > > Shottky barrier diodes tend to have higher junction capacitance. > > Trr is very fast - but for this application you don't want them conducting > if you can help it. > > If you are using an inverse-parallel pair - you don't need the higher > voltage 5819, the lower voltage 5817 is more than enough. > > Unless something else clamps reverse voltage - shottky diodes themselves > can be vulnerable to ESD. > > Shottky diodes have about 1/3 the Vf of regular silicon diodes.
Hello Ian, and thanks for all the input. Realizing I was half awake when I made my first posting, and that it left a great deal to be desired, I have posted the schematic and notes I am using to ABSE under the subject "RF Amp for rabbitears" in hopes that it might help. Do you think that 1N5817s would actually be a better choice for the job of the 1N5819s I have in the schematic? I would hate it if they weren't sturdy enough to stand up to someone walking across the carpet and touching the rabbit eats antenna. Sorry I am just getting back to this. but the wife ran my butt off all weekend. Thanks again for any further input. Dave