Serit LNB DC supply

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A number of people on the BATC forum have reported their Serit tuners are no longer outputting the LNB voltage from one of the F sockets. The cause is inevitably an open circuit inductor (L101 or L102) after the output has been accidently short circuited.

This page describes how to repait the tuner and also a new PCB with DC current limiting available from the BATC shop.

Repairing the Serit DC output

It is very easy to blow up the RF choke feeding DC to the F type inputs before connecting to a dummy load or short circuit antenna - or by just shorting the centre pin to ground. The result is DC on the connector on the main board but no DC on the F type center.

Each F type is fed by a seperate RFC which looks like a ceramic capacitor and is shown in the picture below. These can be replaced with care with a normal leaded RFC or SMD RFC.

Serit rfc.JPG


Dave M5TXJ posted this modification on the BATC forum using a 10uh wire ended inductor. Note - to repair the other F socket feed, the dc input pin to the NIM is the one directly below the one used in the photo.

5222019161032.jpg


LNB power supply with current limit for MiniTiouner

In CQ-TV 265 (Sept 2019) Colin, G4KLB, describes an add on PCB to provide current limiting using the RT5047 device.

The PCB is available from the BATC shop https://batc.org.uk/category/usb-receivers/

Parts list File:RT5047 LNB POWER REV 2-1 PARTS.xlsx

Schematic PDF File:RT5047 LNB Power.pdf


Schematic

RT5047 LNB POWER REV 2-1.jpg

PCB fitted to standard enclosure

IMG 9402.jpg

PCBs

IMG 9631.jpgIMG 9634.jpg

Wiring to MiniTiouner v2.0

Pin 1.jpg

Pin 2.jpg