Yaesu FT-817 IF Tap for SDR

As with my other radios (IC-756pro3 IF Tap page, IC-910H IF Tap page & IC-706mk2G IF Tap page) I wanted to tap the IF (Intermediate Frequency 68.33MHz) out of my Yaesu FT-817 to allow monitoring on an SDR radio and associated software,  I mainly use my FT-817 as a piece of test equipment and having the ability to connect additional equipment to the IF output has already found to be useful.

An example being  as I constructed and tested a portable 6m quad antenna I connecting an RF Explorer analyser to the IF output to measure the RX level of an Elecraft XG-3 RF generator in dBm.

IF Tap Location and Installation

This is the final positioning of the IF Tap modification, which shows the location of the IF tap on the PCB, IF buffer amp* plus DC connection and the IF output (phono) connector alongside the already fitted BHI noise reduction board.

 FT-817_Layout

* The IF buffer amp used was a Clifton Labs Z10000 board I had lying around, but see the G4HUP PAT boards as a better and cheaper alternative.

Schematic

The IF Tap location is before the 1st filter, between D1058, L1035 and XF1001, so the IF bandwidth available to the SDR is quite large, happy days.

IF_Tap_Point-Schematic

IF Tap PCB Location

The IF tap point, D1058/L1035/XF1001 is easily accessed on the main PCB which is under the top case, this PCB image is orientated with the front panel at the bottom.

IF_Tap_Point-Main_PCB

The images below are orientated with the front controls at the top of the image (opposite to the first image above).

IF Tap location IF Tap location

I used some RG-316 to connect the XF1001 tap point to the Z10000 IF buffer amp board

IF Tap location close up

IF Buffer Amp Mounting

The Clifton Labs Z10000 has a single mounting hole, which is very usefully located such that it mounts in the FT-817 right in a gap between some components and looks like it should be there.

You can see the Z10000 board in the middle, I’ve put a yellow mark round it to make it stand out in the photo, and the single mounting hole on the top right of the Z10000 board.

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To ensure the Z10000 board doesn’t short against anything I put a metal pillar between the Z10000 and FT-817 PCB, this did mean I needed to also use a longer screw (this photo was taken before I tightened the Z10000 board down so it appears offset).

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Rear Panel Connection

The FT-817 does not have much space on the rear panel for an additional connector but a carefully positioned hole will do the trick.  As with all my IF tap mods, I use phono connections for the IF output from the radio.  I used to use SMAs in the past but SMAs became cumbersome for something where loss is not so important.

I positioned the hole for the phono connector between the DC and Key inputs.

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This was one of the few places where there were no components behind the rear panel.

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I then put a small label on the back to remind me what the connector is for, and what frequency to tune the SDR to.

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DC Power to PAT Board

To power the Z10000 circuit I took a feed from the 9v line in the Yaesu FT-817.  This is easily accessed from Q1082/TP1084 on the top of the main board.

DC_Point-Main_PCB

This is the same point that the BHI Noise Reduction PCB takes it power from, you can see both DC power leads in the picture.

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