[time-nuts] GPS from a window seat

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Oct 2 02:39:11 UTC 2009

Magnus Danielson wrote:
> jmfranke wrote:
>> I used a bias tee with a capacitor block.  I varied the resistor
>> until I could see signals coming from the external antenna, the built
>> in patch was shielded with aluminum foil and the receiver verified
>> that no signals were coming from the internal antenna.  Some
>> receivers needed only a 10K resistor, some models needed 220 Ohms.
> In my case I still want it to pass 5 VDC, but let the receiver see
> some additional current, so I put a coil in series with the resistor,
> to not load the RF too much.
> Cheers,
> Magnus
You need to ensure that the coil/inductor doesn't have its first
resonance below 1575.42MHz for an L1 receiver, otherwise it isn't very
There are some wideband chokes with first resonances well above 10GHz
when mounted correctly.


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