[Elecraft] Elecraft RF Probe

[Jack Brindle]

Interesting solution. Be aware that neon lamps fire at about 60-70  
volts. At that voltage you have _definitely_ exceeded the PRV of a  
1N4148! You might want to consider a heavier diode in this  
application - the 1N4007 should take quite a bit higher PRV, allowing  
the neon lamp to illuminate with extinguishing the diode.


On May 22, 2006, at 6:25 PM, Mike Scott wrote:

> Now, that solution shows the power of the group!
> All this piker could do was look up a 200V diode or suggest  
> connecting two
> in series.
>
> When the NE-51 lights you know you have exceeded the diode reverse  
> voltage!
> And it's time to add a resistance pad.
>
> Mike Scott
>
> AE6WA
> Tarzana, CA
>
> Elecraft KX1
> 40M Inverted V
> 20M Dipole
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net]On Behalf Of Al Gulseth
> Sent: Monday, May 22, 2006 5:44 PM
> To: elecraft at mailman.qth.net; srife at swbell.net
> Subject: Re: [Elecraft] Elecraft RF Probe
>
>
> Funny you should mention that -- just in the past few days I was  
> browsing
> through an old [1968 edition] ARRL "Hints and Kinks". In an article  
> titled
> "Diode Protection for the Heath R.F. Probe" the author suggested  
> adding a
> NE-51 neon lamp across the diode (a solution he came up with after  
> frying
> "three or four" 1N34s). This should work for the Elecraft probe as the
> schematic shown in H&K for the Heath probe is virtually identical  
> to the
> schematic in the K1 manual (the only difference is a .005 vs. .01  
> cap for
> the
> input coupling and the polarity of the diode).
>
> 73 es GL, Al
>
> On Mon May 22 2006 06:53 pm, elecraft-request at mailman.qth.net wrote:
>> Date: Mon, 22 May 2006 17:22:23 -0500
>> From: "Stan Rife" <srife at swbell.net>
>> Subject: [Elecraft] Elecraft RF Probe
>> To: <elecraft at mailman.qth.net>
>> Message-ID: <007701c67dee$339355a0$6401a8c0 at stansdesktop>
>> Content-Type: text/plain;       charset="US-ASCII"
>>
>>         I forgot to mention that I put a 1N4148 in and it seems to  
>> have
>> taken it out too.
>>
>>
>>         I put too much voltage on my poor probe. Is there a  
>> heavier diode
>> that will take a little more voltage, say around 70v, that I can  
>> replace
>> the 1N31A with?
>>
>>
>> Stan Rife
>> W5EWA
>> Houston, TX
>> K2 S/N 4216
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-Jack Brindle, W6FB
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