Electronics > RF, Microwave, Ham Radio

Look what the cat dragged home: Phase Atlantic microwave amp (?)

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wkb:
I hacked it up a bit to remove the 2 splitter circuits from the output to obtain a single input/single output amplifier.  A sweep with the SA shows the attached image.
With -6dBm input power.

Goes without saying that my SA cannot get to the frequency this amplifier is designed for (i.e. 1.7-1.8 GHz).  The directional couplers Anaren 1A1305-3
it uses are designed for 1.5-2.2GHz.

Wilko

TheSteve:
Just think, now you have an excuse to buy a new spectrum analyzer that goes to 3+ GHz.

wkb:

--- Quote from: TheSteve on February 26, 2016, 05:52:53 pm ---Just think, now you have an excuse to buy a new spectrum analyzer that goes to 3+ GHz.

--- End quote ---

Don't rub it in. Couple of weeks I bumped into a nice portable HP 22GHz incl TG. €900
😂😅

But you can spend a € only once

kazam:
I would say Wilkinson dividers and not 180degree hybrids.

Can't really get a lot of power from those transistors though so I'm wondering if this was some kind of measurement amp?

Normally you have two inputs on the BTS antenna, +/-45 deg polarization. Here, you're splitting into 4 equal outputs. Why?

Good find!


--- Quote from: German_EE on February 15, 2016, 06:16:40 pm ---Working from left to right the signal comes in and is filtered, it then passes through two MMIC amplifier stages before hitting the main power amplifier assembly. The main power amplifier uses 2 x 90 degree hybrids and two more higher power amplifier chips (the yellow devices), it's done like this to improve transmit IMD and ensure a 50 ohm impedance on both the amplifier input and output. Finally the amplified signal is split into four using three 180 degree hybrids.

The circuits at the bottom are either for bias or transmit/receive switching.

--- End quote ---

KJDS:

--- Quote from: kazam on February 28, 2016, 11:50:54 am ---
Normally you have two inputs on the BTS antenna, +/-45 deg polarization. Here, you're splitting into 4 equal outputs. Why?

--- End quote ---

A big GSM basestation will be running four carriers on both transmit and receive on each sector, hence wanting four outputs from the pre-amp to go to four receivers, one for each carrier.

I've occasionally seen eight carrier set-ups, but very very rare.

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