This document has notes on amplifier development and a list of off-shelf amps in testing and available to buy and other misc notes.

This doc is mostly related to the improvement of the CX Cards SNR or signal-to-noise ratio.

Order Links: ADA4857 KoFi / ADA4857 PCBway

Developed by Rene Wolf as a second generation, "adjust per unit" impedence matched amplifier board based around using two ADA4857 aplifyer ICs with 0805 pads for gain/input termination so requires an assortment resistor book and a entry to mid range benchtop type digital store oscilloscope.

Full name vhs-rf-amp-ada4857 ADA4857 GitLab Repo.

The AD8367 is no longer recommended as the input termination is internal to the IC at 200Ohm, and using 0603 parts making it harder to modify to suit and match impedance for a VCR and the default 200ohm is often not optimal on all decks, the ADA4857 is recommended instead, but this can work for some decks not all.

The AD8367 boards are 3-5v range only if voltage is 6-12v+ a buck boost converter or regulator to lower the voltage will be required. Jumper configuration in automatic gain mode "AGC" is both pairs with jumpers as shown in image.

The most commonly deployed off-shelf RMS amplifier considered the go-to for HiFi/Video FM from tape and laserdisc formats, using 0603 parts it can be user modified if required.

AliExpress

GitLab Repo

Rene Wolf's first generation amplifier for due duel channel capture using the sgm8302 amplifier IC.

An off shelf board that is widely available on AliExpress.

(Confirmed on LD players)

Used by the DomesDayDuplicator

https://www.aliexpress.com/item/AD605-VGA-Dual-Channel-Voltage-module-Control-Adjustable-Gain-Amplifier-Module-Low-Noise-High-Precision-5V/33026097817.html 23GBP with VAT

The way the board is supplied, the 2 channels aren't configured the same.

Absolute gain range programmable −14 dB to +34 dB (FBK shorted to OUT) through 0 dB to 48 dB (FBK open)

One channel has FBK shorted to OUT (-14 to +34) gain range, and the other channel has FBK open (0 to 48db) range, controlled by R5 and R6.

Used by the DomesDayDuplicator

https://www.aliexpress.com/item/33008732817.html

https://www.aliexpress.com/item/32790115607.html

Analog Devices Linear Technology LT1252 Low-Cost Video Amplifier (built for application used by CubeTec's BetaCam add-in boards for example)