[time-nuts] GPS antenna splitter recommendation?

[John Ackermann N8UR]

So, being a heartless butcher I opened up one of the HP 8-port GPS
splitters (forget the number) and removed the sawtooth filters so the
unit would pass both L1 and L2.

I found that to bridge the filter pads even the smallest cap I had (I
think 7pf) caused problems.  I ended up making "gimmick" capacitors out
of a couple of inches of #26 magnet wire twisted together.  That has
worked well; there's a little difference in gain between ports, but not
enough to worry about.

John
----

On 4/30/20 11:39 AM, Bob kb8tq wrote:
> Hi
> 
> 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 ….
> 
> Bob
> 
>> On Apr 30, 2020, at 9:25 AM, Ben Hall <kd5byb at gmail.com> wrote:
>>
>> On 4/30/2020 7:33 AM, Bob kb8tq wrote:
>>> Pretty much all the Mini Circuits splitters will pass DC.
>>
>> Hi Bob and all,
>>
>> That's absolutely correct.  Something you might consider is what I did - I got a pair of Mini-Circuits ZC6PD-1900W's cheap on the e-place. Frequency-wise and loss-wise, not perfect, but good enough for me. Problem was, like you note, all the ports are DC-pass, and I wanted only output port 1 to be supplying DC to the antenna.
>>
>> So I opened mine up, carefully cut the trace going to outputs 2 and up, and bridged them with, IIRC, a 0.01uF ceramic capacitor to block DC.
>>
>> Before and after plots on the VNA at work showed very little increase in loss after the mod compared to before the mod.
>>
>> Just some food for thought.  :)
>>
>> thanks much and 73,
>> ben, kd5byb
>>
>>
>>
>>
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> 
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