From: Gerhard Hickl <gerhard.hickl@aon.at>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <4C1A271605FB0B62@smtp208.alice.it> (added by postmaster@alice.it)
References: <000c01cb5a7a$44cfcc50$0401a8c0@xphd97xgq27nyf>
	 <4C1A271605FB0B62@smtp208.alice.it> (added by postmaster@alice.it)
Date: Wed, 22 Sep 2010 21:50:12 +0200
Message-ID: <1285185012.2042.23.camel@gerhard-desktop>
Mime-Version: 1.0
Subject: Re: LF: PA0RDT miniwhip in TX?
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


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
> 
>