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Date: Wed, 22 Sep 2010 16:05:08 -0400
From: John Andrews <w1tag@charter.net>
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Subject: Re: LF: PA0RDT miniwhip in TX?
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Another approach is to include a small 12V "telephone" type relay at the 
input to the amplifier, and powered from the same source. The relay 
would short the input when de-energized.

John, W1TAG

On 9/22/2010 3:50 PM, Gerhard Hickl wrote:
> Hello Marco !
>
> I'm currently also playing around with a MiniWhip and had exactly the
> same concerns.
>
> It's not the original design because the 2N5109 wasn't available and so
> I used a 2SC24?? (don't remember but a RF-NPN up to 1.5Ghz). I had to
> reduce the collector current by increasing the emitter-resistor up to
> 680R but noticed no loss in performance.
>
> I would suggest to decouple the gate of the J310 with a capacitor(100n)
> from the "receiving" portion of the PCB and use anti-parallel diodes to
> limit the voltage. Maybe this will not remove all the voltage from the
> gate but at least the "dangerous" level.
>
> I will try this in the next version of the antenna.
>
> 73 es gl
>
> OE3GHB
> Gerhard
>
>
>
>
>
> Am Mittwoch, den 22.09.2010, 21:08 +0200 schrieb Marco IK1ODO:
>> No, I don't want to transmit with the miniwhip :-) !!!
>> The question is, how does the miniwhip behave in an electric field of
>> some kV/m, that is, close to the transmitting antenna in 137 or 500
>> kHz? Any experience on that?
>> A friend (IK1HSS) wants to know, before frying an infinite series of
>> J310. In theory the junction should handle up to 25 V reverse, but
>> this is not too much, after all.
>>
>> 73 - Marco IK1ODO
>>
>>
>
>
>
>