Thread by @2ftg1

This commercial GPS antenna was very much not I was expecting on the inside.
A thread about this #Lband #surplus

So on the outside it looks like a normal, if a bit large GPS antenna with the usual ceramic patch antenna.

Well, the inside is very much different.
There's stuff in there.
Way too much stuff in fact.

So let's start from the antenna input and work our way out.
The two SAW's are normal 1575MHz GPS L1 band one's.
But a SOIC-8 LNA? 🤪

It's a M/A-COM MAAM12021 1.5 - 1.6 GHz Low Noise Amplifier.
With the low noise of 1.55dB.
In a normal GPS antenna this would be it.
Maybe a second gainstage.
But,

... There's way too much stuff in there.
And some if it looks balanced??
And there's RF cans, those have no place on 1.5GHz.

Here's the chip.
Zarlink GP2015.
A GPS Receiver RF Front End.
So they put the whole damn GPS frontend at the antenna.
It's a funky triple conversion deal.
Here's the datasheet for it:
prkele.prk.tky.fi/~ftg/files/dat…

Gaze upon it.
175.42MHz 1st IF
35.42MHz 2nd IF
4.309MHz 3rd IF
That's HF!
This thing is an L-band to HF converter.
This would have ruled with Inmarsat-A.

Here's the DC/4.309MHz/10MHz input triplexer of the thing.

This, I think is the 175.42MHz 1st IF filter.

Only regulator in the whole thing.

The last remaining active in this thing is the IF amp, a NEC MMIC marked "C1F", which is familiar from Ku-band LNB's.
A NEC UPC2710T.
Should have around 33dB gain.
It's datasheet can be found here:
aliot.com.ua/pdf/upc2710.pdf

Made by Meinberg.
So what's next?
Well I should actually wire up a triplexer for it, or just solder a 10MHz TCXO inside the box, that has been floating around the desk now for at least a month.
I should also solder the SAW filters back on, before I loose them.
We'll see.
EOF🧵