Echostar LNB Model BKU235x modification
On a surplus market I bought 3 of these LNB's.
I found out that
they where easily converted to the 10GHz band with an output power of 45mW
or to 250mW with a mgf1801.
The LNB has 2 DRO oscillators, on 9.75 GHz and on 10.6 GHz.
I decided to saw the 9.75 GHz DRO chamber off and convert the 10.6 GHz DRO
for DRO modulation.
This is a real good design because the end result of this converted LNB delivered
superb video quality.
With scissors I removed the unused pcb.
These removed pcb's
contain nice things like pin diode's, 10GHz diode, and some more smd parts
which can be used again.
On the furnace I removed all the smd parts from
the 10GHz print.
I laid the 3 Fet's with its 2 capacitors aside because these
have to be resoldered back again with the drain towards the output.
a fet can be recognized with an ohm meter.
There is about 6 to 20 ohm resistance
between drain and source.
The resistance between gate and source/drain is
high: approximatly 3 Meg.
If you replace the fet, please be sure there is
no tin between its pin's.
This can also be checked with an ohm meter before
and after soldering the fet.
Before soldering anything, you must edit the 10
A 50 Ohm stripline must be laid from the oscillator to the first
Remove the filter, but not everything because some cupper can be
used to fix the new stripline to.
Near the place of the fets you see tuning
If you have power measurement equipment for 10GHz you may remove these
to experiment with new stubs.
Tuning the last Fet is enough to acquire maximum
It is also possible to get more power to replace the last fet with
an MGF 1801.
Tuning al fets will then give a power of about 250mW with the
In case of three original fets place the components like this.
A closup of the same schematic in reality
A lot of material can be removed and reused for other purposes
Here I am measuring the output power of the DRO alone.
With this way I can tune the DRO to the desired frequency
Left : original 10.6 GHz puck
Middle : new 10.6 GHz puck + cutted puck from Right
Right : old cutted 9.75 GHz puck
I tuned my DRO to 10.400 by adjusting the puck size.
Finished and tuned to 10.4 GHz with 45mW power.