Re: Kiwi front end protection.


Glenn Elmore
 

Rolf,

JKS has put protection diodes at the input to the preamp on the Kiwi board which can handle significant power. But given the distance and the difficulty of ever achieving high coupling between antennas in the far field, I really doubt that you will damage anything from your contester's operation.  Even a matched dipole on your end against, say, 10 kW ERP at 1/3 mile on 14 MHz only results in 100 mW which isn't enough to cause physical damage to the Kiwi. In all likelihood things are ten's of dB safer than that. You would likely have to work very hard to actually damage a Kiwi in the circumstance you describe, I think.

Having said that, once aggregate input exceeds about -15 dBm, the top of Kiwi ADC is exceeded and things go bad immediately so you'll not be able to use it during his transmissions. But just to make the point, I've actually run nearly full duplex from my own 20m station by transmitting on a 60' high dipole and receiving on a broadband active antenna. It was rather fun to be 'full QSK' on SSB or CW.

In short, were it me, I'd not worry about physical damage but I'd be prepared to lose operation during transmission peaks.


On 7/24/21 8:17 AM, Rolf Ekstrand wrote:
Good morning y'all,

In regards to my expansion plans I am thinking of putting up some fixed gain antennas.  However in the EU direction I have a high power DX/contester station about 1/3 of a mile away and my concern is front end overloading and protection of the Kiwi with increased gain in that direction. It is pretty bad at times as is with the omni antenna.   I had the Kiwi schematic some place, but can't find it now, and with the ongoing Kiwi bru hah hoopla the link is not seemingly accessible.    

Anyone  out there in WD land that have info on the front end protection of the Kiwi and/or experience with close in band high power transmissions.  

73 Rolf K9DZT

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