I have a few of the 2 in 5 out video distribution amps. I took one apart and converted it to 50Ω from 75Ω, and to be honest, I can't really see a difference.
Bob On Fri, Oct 18, 2019 at 8:08 AM Charles Steinmetz <[email protected]> wrote: > Taka Kamiya wrote: > > > I am using Extron MDA 3V for distributing 10MHz at several places in my > lab. MDA3V is a one port in - 3 port out device made for VIDEO market and > rather low end at that. Input and output is 75 ohm and bandwidth extend to > 150MHz or so. Looking at 10MHz sine wave through it, it looks good. No > visible distortions. Gain is unity between input and one of the ports. > > > > Couple of questions though. This device is 75ohm. It's easy to add > 150ohm in parallel to a matching resister and make it 50ohm. However, I'm > guessing 50 ohm / 75 ohm mismatch is not really a big deal that I'm not > doing anything about it. Input and output cables are RG58 (50 ohm) VSWR > is 1.5, For external sync port, many equipment is not exactly spec'd for 50 > ohm, but often only spec'd for voltage or at db level without any specific > impedance mentioned. Recommended cable is 50 ohm though. I typically shy > away from consumer grade gear but looking inside, it's just an op-amp and > registers. If I use square wave which contains higher frequency > components, would this be inadequate? > > There are many web pages by people doing exactly what I'm doing with > usually bigger Extron devices. I'd like to consult the Time-Nut community > of sanity in what I am doing. > > I published a doc with recommended mods to the opamp-based Extron video > DAs for use as 1-10MHz clock/timing DAs: > > < > http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Extron_ADA_6_modifications_for_use_as_10MHz_distribution_amp_STEINMETZ.pdf > > > > Whether you make the changes or not, you may find some helpful > information there. > > Best regards, > > Charles > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
