[TowerTalk] YCCC 9 circle preamp failure test

[Wes]

On 9/24/2019 1:36 PM, jimlux wrote:
> On 9/24/19 1:14 PM, Wes wrote:
>> Why all of the complications?  The preamps are unity gain. 
>
> Aha.. I was hunting around for a circuit description. Yeah, it looks there's a 
> noninverting buffer followed by a 1:1 transformer.
>
> So it's more of an impedance buffer.  What Z does it present to the element?
>
> (I do a lot of work with HF receivers that use short (2-3 meter) antennas 
> feeding high Z buffers, so they're more "E-field" probes)

  Can't be more than 50K ohm (the parallel combination of the two bias 
resistors).  I don't know what the 5pF cap is doing, maybe suppressing something 
or the other, otherwise, it's contraindicated.   IMHO, of course.

Wes  N7WS