[time-nuts] GPS antenna splitter recommendation?

[Ben Hall]

On 4/30/2020 10:39 AM, Bob kb8tq wrote:
> At 1.5 GHz something like a 50 to 100 pf NPO is probably the best
> pick for a blocking cap.
> 
> Why? It does a fine job at the intended frequency. It acts as a high pass
> down lower where lightning energy is a bit higher ….

Hi Bob and all,

You are 100% correct!  I decided to look up my notes on my modification 
and I see that I did use a 100 pF NPO cap versus the 0.01 uF value I 
originally mentioned.  I should know better than to try to remember 
anything off of the top of my head like that.  :(

I'll bet that I used 100 pF based on discussions here, as it's almost 
impossible I would have made the right choice on my own!  I'm a 
mechanical engineer, after all...  ;)

I also found my VNA test results:  my modified splitter was -9.1 dB loss 
at 1.525 GHz.  :)  Theoretical should be 7.8 dB, so it's not great, but 
it's not horrible either.

Works just fine - feeding two Trueposition units, an NTP server, a 
lightning detector, and a uBlox M8N.  When my HP Z3801 was working, it 
was on the sixth port...but it went nuts about six months ago and since 
I had the TruePosition units, I never bothered to do more than basic 
troubleshooting on it.

thanks much and 73,
ben, kd5byb