it never happens as you expect....
In the last week of August i got my "DuoBand-Feed 2,4 / 10 GHz - LNB" from BaMaTech (https://www.bamatech.net/anten…-feed-2-4-10-ghz-lnb.html). A real great piece of hardware.
Before buying, i asked Markus for the LNB type to know how to modify for a TCXO and he told me, he uses a Opticum Red LSP-02G.
So i was happy so far, the LSP-02G seems to be easy to modify. All parts on top, everything accessible and well known (see http://www.pabr.org/radio/lnbl…lnblineup.en.html#LSP-02G).
Then the parcel arrived and i opend the LNB housing which was labeled "LSP-02G". But something was wrong, the LNB doesn't look like a "LSP-02G"....Damn! (BTW: i don't blame Markus for that, just my bad luck!)
I analyzed the PCB and it seems, that Opticum now sells the Opticum Red "Robust" as "LSP-02G" (see http://www.pabr.org/radio/lnblineup/lnblineup.en.html#Robust).
The differences of the both boards was the solder mask (green at the LSP-02G instead of black of the Robust) and the code marking of the transistors. The block diagram can be found at the attachments.
The LNB is a "two chip" design with an integrated power supply chip D4202 from Silicore for all LNA stages including a 22kHz detector and a NXP TFF1015 PLL/mixer. Unfortunately there is no datasheet for the D4202 available. Hopefully the external clock can be fed through XO1 of the TFF1015.
The modification of this type of LNB seems to be really hard. The is only a little cavity on the bottom side where the crystal is soldered, where modification parts can be placed.
So i decided to order two Robusts and give it another try to do a TCXO modification.
The silicon seal can be removed very good with "SOUDAL Silicon Remover". If everything has been cleaned (PCB, housing, ...) the crystal has to be removed carefully.
I put some kapton tape at the area of the crystal and placed a STM L78L33ABU there. The supply can be connected to a via near this area.
Next i will place the TCXO on top of the regulator and connect it via a 1nF capacitor to the crystal pad which leads to XO1 (the block diagram of the modification isn't that detailed!). In progress, stay tuned...
The crystal cavity of the LNB housing is isolated with kapton tape to avoid short circuits of the extra parts with GND.
As an intermediate result i would say, that it would be possible to modify this LNB for TCXO usage, but it is nothing for the feint-hearted. You need a good microscope, good tools and a steady hand.
It would be easier to insert a series resonant circuit for external clock sourcing (which I do not prefer) or to use an external correction.
The modification hasn't finished yet, so I am curious, if the LNB will work again.
Just for your information...be warned