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
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