Elecraft

Re: [Elecraft_K3] Re: P3 adding rf protection diodes question

Classic

List

Threaded

2 messages Options

Fred Townsend-2

Re: [Elecraft_K3] Re: P3 adding rf protection diodes question

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Alan Bloom

Re: [Elecraft_K3] Re: P3 adding rf protection diodes question

BNC connectors are designed in such a way that the shield always
connects before the center conductor when you plug it in. The only way
to get a static discharge into a female BNC is to somehow touch the
center conductor (with your finger or whatever) without touching the
shell. You would need to use a tool to do that unless you have REALLY
skinny fingers. :=)

Alan N1AL

On 05/20/2014 11:31 AM, Fred Townsend [hidden email]
[Elecraft_K3] wrote:

>
>
> Alan, thank you for the good information on how to setup the P3 as a
> "poor ham's spectrum analyzer". However I must disagree with your first
> statement. Diodes for ESD protection are needed in normal use with the
> K3. When ESD occures it is frequently at connector interfaces because
> the two mating bodies may be at different potentials. Good design
> practice for ESD is to protect connector interfaces if the user will be
> mateing and un-mateing. This is clearly the case with the K3/P3
> combination. Diodes are soo cheap when applied in the SMD process it
> seems like a no brainer to include ESD protection. Defeat Murphies law.
>
> 73
>
> Fred, AE6QL
>
>
> -----Original Message-----
> From: "Alan Bloom [hidden email] [Elecraft_K3]"
> Sent: May 20, 2014 10:42 AM
> To: [hidden email], [hidden email]
> Subject: [Elecraft_K3] Re: [Elecraft] P3 adding rf protection diodes
> question
>
> The diodes are not needed in the normal situation where the P3 is
> connected to the K3 IF output.
>
> You can use the P3 as a kind of "poor ham's spectrum analyzer" by going
> into the menu and setting "Xcvr Sel" to the last item in the list,
> labeled "0 Hz". Now the frequency displayed is the actual RF frequency
> of the IF input, not the K3 frequency. The "XCVR" RS-232 connector
> should be disconnected from the K3 in this case. Tune the frequency
> with the CENTER control. (Make sure the "CenterEn" menu item is "ON".)
>
> If you do that you should add the back-to-back diodes in parallel with
> the input BNC connector. Standard 1N4148 or similar switching diodes
> are
> fine. If you don't want to modify the P3 you can do what I did: Add
> the back-to-back diodes to a male BNC connector and connect that to a
> BNC "T" plugged into the P3 IF IN.
>
> There may be some slight degradation of dynamic range. The third-order
> intercept of the P3'! s preamplifier is about +9 dBm (0.6 Vrms). If
> you're worried about it you can use two diodes in series in each leg (4
> diodes total) to reduce the distortion contribution from the diodes.
>
> Alan N1AL
>
> On 05/19/2014 06:38 AM, Sam Morgan wrote:
> > It was mentioned to put a couple of diodes across the P3's input to
> > protect it. Do the diodes need to be 1n34a's or would 1n4148's be
> ok for
> > that application?
> >
> > I had tried repeatedly to ask Don W3FPR this question off list via
> > direct email, but I guess all my efforts have ended up in his spam
> > folder?? :-(
>
>
>
> __._,_.___
> ------------------------------------------------------------------------
> Posted by: Fred Townsend <[hidden email]>
> ------------------------------------------------------------------------
>
>
> Visit Your Group
> <https://groups.yahoo.com/neo/groups/Elecraft_K3/info;_ylc=X3oDMTJmNDJlbDlnBF9TAzk3MzU5NzE0BGdycElkAzIwMTQ5NDI4BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0MDA2MTA2OTg->
>
>
> * New Members
> <https://groups.yahoo.com/neo/groups/Elecraft_K3/members/all;_ylc=X3oDMTJndWNlaThrBF9TAzk3MzU5NzE0BGdycElkAzIwMTQ5NDI4BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxNDAwNjEwNjk4>
> 3
>
> Yahoo! Groups
> <https://groups.yahoo.com/neo;_ylc=X3oDMTJldDVkOTNjBF9TAzk3NDc2NTkwBGdycElkAzIwMTQ5NDI4BGdycHNwSWQDMTcwNTA2MzEwOARzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQwMDYxMDY5OA-->
>
> • Privacy <https://info.yahoo.com/privacy/us/yahoo/groups/details.html>
> • Unsubscribe
> <mailto:[hidden email]?subject=Unsubscribe> •
> Terms of Use <https://info.yahoo.com/legal/us/yahoo/utos/terms/>
>
> __,_._,___