[Skimmertalk] RP-16 front end tenderness

[Bob Wilson, N6TV]

On Thu, Jul 11, 2019 at 1:18 PM Ted Gisske <gisske at offex.com> wrote:

> https://www.redpitaya.com/p52/stemlab-12288-16-sdr-kit-basic
>
>
>
> Scroll down to “RF Inputs”.
>
> “Absolute Max. Input volt range: DC max 50V (AC-coupled), 1 Vpp for RF”
>

Thanks, but this phrase doesn't make much sense.  What does "AC-coupled" DC
mean?  I see a 100 nF blocking capacitor in series with the SMA connector
(perhaps 50V max rating).  Given that, you cannot feed any DC into the SMA
connector and expect to get any output.

I don't know that we can believe the "1 Vpp for RF" statement, which seems
way too conservative.  More volts could certainly overload the ADC (0.5V
full scale), but it shouldn't destroy it, or any components before it.  I
think further study is required before concluding that the RP will be
damaged if you feed more than 20mW (1V at 50 ohms per
https://www.pasternack.com/t-calculator-power-conv.aspx).


> My goal is to keep my skimmer up during contests. I’ve loaded all observed
> variations and bastardizations of K9IMM into my bad call list in
> Aggregator, so they don’t go to the RBN. I’ve been running my QS1R in
> contests for years with no problems. I do run my skimmer in a pole-shed on
> my farm, about 150’ from any transmitting antenna.
>

Congratulations on that.  Not easy to achieve.

73,
Bob, N6TV
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