[Elecraft] P3 adding rf protection diodes question

[Kenneth A Christiansen]

Hi Joe.

I think you could use the 1n148 diodes and they should be OK across the input of the Elecraft P3. The problem is from larger static voltages that could destroy the solid state devices in the P3 but with the two diodes back to back the static voltages should be held to 0.6 volts and that low voltage should not cause any failure. The 0.6 volts may even be better than the 0.3 volt of the 1N34A as there will be less chance of inter mod distortion.

73 and good luck finding your noise.

Ken  W0CZ  w0cz at i29 dot net

Sent from my iPad

> On May 19, 2014, at 10:31 AM, Sam Morgan <k5oai.sam at gmail.com> wrote:
> 
> Joe,
> apples and oranges perhaps?
> I think you answered the question as if I was asking about the K3's input...where as I was asking about the *P3* input which had no gas discharge protection.
> 
> Perhaps I should have mentioned I was speaking of using a standalone P3 for the purpose of chasing rfi, as mentioned in a previous thread:
> 
> [Elecraft] P3 as a portable RFI bandscope?
> by Jim Miller Sat, 17 May 2014 16:48:07 -0700
> 
> http://elecraft.365791.n2.nabble.com/P3-as-a-portable-RFI-bandscope-tt7589211.html
> 
> 
>> On 5/19/2014 9:20 AM, Joe Subich, W4TV wrote:
>> 
>> On 2014-05-19 9:38 AM, Sam Morgan wrote:
>> > It was mentioned to put a couple of diodes across the P3's input to
>> > protect it.
>> 
>> Don't!  Back to back diodes will degrade the strong signal handling
>> of the K3 and the receive inputs already include protection including
>> gas discharge and a signal level detector that disconnects the input
>> if the level becomes too high.
>> 
>> 73,
>>    ... Joe, W4TV
>> 
>>> On 2014-05-19 9:38 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?
> 
> 
> -- 
> GB & 73
> K5OAI
> Sam Morgan
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