[time-nuts] Extron ADA 6 as 1/5/10 MHz DA

[Charles P. Steinmetz]

What I have been referring to as the "plain ADA 6" is properly known 
as the ADA 6 Component:

<www.extron.com/download/files/userman/ADA6ComponentB.pdf>

Judging from the dates on some of Extron's documents, it appears to 
be a newer model than the ADA 6 300 series -- which is consistent 
with Bruce's comment that his ADA 6 300MX had through-hole 
resistors.  Accordingly, it is possible that the ADA 6 300 models do 
not share the circuit I attached to my last e-mail.  As always, use 
due diligence!

Best regards,

Charles


>Following the recent discussion of using the Extron ADA 6 as a 
>distribution amplifier for 1/5/10 MHz reference signals, I dug out 
>the schematic of the amplifiers and typed up my notes re: 
>modifications (see attached).
>
>Note that the ones I have are "plain" ADA 6's, not "MX" or 
>"MX-HV."  I do not know if the MX or MX-HV units use this circuit 
>or, if they do, if the component numbers are the same.  However, the 
>gain-switching circuitry is present on the "plain" ADA 6 PC cards 
>(but the switch itself is not), which leads me to believe that at 
>least the MX version was built with this same card.
>
>There may be other Extron video DAs that use this circuit -- in 
>particular, models that have a PC card parallel to the rear panel 
>and mounted to it by the BNC connectors may do so.
>
>There is another, discrete design that Extron apparently produced at 
>the same time, one example of which is the ADA 3 180.  This design 
>cannot drive 50 ohm loads to +13dBm (1 Vrms) without severe 
>distortion (negative peak clipping), so you need to attenuate the 
>typical 1 Vrms input signal 6 dB to stay out of 
>clipping.  Unfortunately, there is no easy way to modify this design 
>to drive +13dBm into 50 ohms (and, IMO, there is a lot not to like 
>about it for any use, including RGB video).  I have a schematic of 
>that circuit, too, if anyone needs it.
>
>Best regards,
>
>Charles