AD8367 RMS Setup

NOTE: The process outlined in this page was intended to be informational with regard to capturing "Laserdisc" RF. If you are intending to only capture VHS RF, you don't need to do this.

• CARD: White PCIe CX23883 card (pic to identify: https://github.com/tandersn/cxadc-hw-mod/blob/main/X_Pictures/cxcard4ad8367/stockCXwhite.jpg)
• AMP: RMS mode configured AD8367 board (pic to identify: https://github.com/tandersn/cxadc-hw-mod/blob/main/X_Pictures/ad8367_RMS/stockAD8367_RMS%20.jpg)
• FILTER: Mini Circuits SXLP-13+ (or BLP-10.7+)
• CRYSTAL: 40MHz - ABRACON ABLS2-40.000MHZ-D4YF-T 18pF 30ppm HC-49/US
• POWER: 3x AAA battery holder with switch: https://raw.githubusercontent.com/tandersn/cxadc-hw-mod/main/X_Pictures/opa657/3aa.jpg
• MISC: resistors, capacitors, small project box, SMA/BNC/RCA adapters and connectors, small zip ties, double sided foam tape

With this setup, and the mods detailed in the pages to the right, i've achieved very good results. PLEASE READ through all the pages before starting, as some of the optional mods negate some of the steps of other mods. For example: Doing the direct wire mod negates the need to remove / replace SMD components on the cx card.

The pros of this setup, and the reasons i put it first are:

• 5v single supply voltage (easy power configuration)
• RMS mode means easy capture of CAV discs (no need to use cxlvlcavdd script or 16 bit)
• overall, less expensive and less complex than opa657 setup.

The cons are:

• The RMS version of the AD8367 board seems very fragile and is damaged easily
• The 200 ohm load requirement of the AD8367 amps mean you have to buy non-standard resistors (~165-170), or use them in 2 in parallel
• The AD8367 has a "self centering" function built in, it doesn't seem to work quite right with laserdisc RF, so this is why the output capacitor is required. In the essence of "less is more", i'd rather have less overall components in the chain.

The last two bullets apply to ALL AD8367 boards.

As mentioned earlier, the RMS board handles CAV discs nicely: (that's an entire capture of ggv1069 test disc)

CX CARD AD8367 RMS setup will get you an SNR readout like this:

Directions for this mod:

• Mod card input components: https://github.com/tandersn/cxadc-hw-mod/wiki/CX-CARD:-Modify-PCIe-CX-card-to-work-with-AD8367-(RMS-or-otherwise)
• Mod card for BNC (optional but recommended): https://github.com/tandersn/cxadc-hw-mod/wiki/CX-CARD:--Replace-RCA-jack-with-BNC-jack

• Mod card for direct wire (optional but recommended): https://github.com/tandersn/cxadc-hw-mod/wiki/CX-CARD:-Direct-Tap-Mod

• Mod AD8367 RMS board: https://github.com/tandersn/cxadc-hw-mod/wiki/AD8367:-RMS-amp-board-modification
• Assemble SXLP13+ LPF: https://github.com/tandersn/cxadc-hw-mod/wiki/Low-Pass-Filter-for-AD8367-set-up

CX CARD AD8367 RMS setup:

AMP --> Filter --> Resistor --> CX Card

In this picture i'm using a very short cable, if you are using longer cables, design your setup so the resistor and filter connect to the card, this will help reduce any possible high frequency interference picked up by the cable.