[time-nuts] Using commercial video amplifier for 10MHz clock distribution.

[timeok at timeok.it]

   Hi,

   A premise must be made to define the performance of these DAs as EXTRON can be compared to those built for the distribution of reference frequencies.
   The Extron is a very nice solution, certainly of modest price, but we must consider that its performances are limited. This especially if we talk about saturation levels but much more important is the low separation between the output channels. These two factors can be negligible if the required level/stability is good but not excellent, in fact by disconnecting a load or simply changing the length of a coax connection on a channel almost certainly a change in level / phase will occur in the adjacent output.

   If anyone is interested, you will find my solution here:

   http://www.timeok.it/wp-content/uploads/2015/08/Frequency-Distribution-Design-Basic-Module-v-4.1.pdf

   Using it as a buffer for the low phase noise HP 10811-60109 and BVA 8600 there is no deterioration of the phase / noise floor.

   I ordered some new PCBs related to the buffer only. If anyone is interested let me know off list.

   Luciano

   timeok at timeok.it


   Da "time-nuts" time-nuts-bounces at lists.febo.com
   A "Discussion of precise time and frequency measurement" time-nuts at lists.febo.com
   Cc
   Data Sat, 19 Oct 2019 08:30:02 +0000
   Oggetto Re: [time-nuts] Using commercial video amplifier for 10MHz clock distribution.
   There is a schematic here on the Extron uploaded by a TN member. The schematic for the Extron looks looks dead simple that one could really just make a simple 3 channel with the included mods in the writeup, only problem is I don't see a source for a CLC409 any longer, and I don't have the experience or knowledge to use a substitute ADA800x ??

   <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>

   -=Bryan=-

   ________________________________
   From: time-nuts <time-nuts-bounces at lists.febo.com> on behalf of ed breya <eb at telight.com>
   Sent: October 18, 2019 1:39 PM
   To: time-nuts at lists.febo.com <time-nuts at lists.febo.com>
   Subject: Re: [time-nuts] Using commercial video amplifier for 10MHz clock distribution.

   I have a Hitachi VD-1000 video distribution unit that's been sitting
   unused for years, waiting until I finally get around to making it into a
   reference unit. I just dug it out and looked inside. It is full of RCA
   jack cables for jumping the signals around in different ways. I
   apparently had changed things around already, to make one section into a
   15-output distributor. I have forgotten all about it long ago, so now
   it's just a dizzying array of cabling. I must have made notes somewhere,
   that I'll have to find for when I eventually (probably fairly soon) do
   the proper conversion.

   It uses CLC404 amplifiers, which appear to be older and a little noisier
   than the CLC409, but should be OK for this. Unfortunately, it uses a
   small switching supply, which I dislike for things like this, so
   ultimately will make a linear one for it.

   This thing has 40 BNC connectors on the back, which would allow for lots
   of I/O and branching combinations. This is likely way more than I'll
   ever need, so the "new" plan is to incorporate some improvements,
   considering what I recently learned during my work on the frequency
   multiplier project. I'll be reducing the total fanout, and changing some
   of the outputs to have fully-floating transformer coupling, to reduce
   ground loop effects in high sensitivity applications, and also
   independent volume controls for some. I may do the same on the source
   inputs too. I don't know how many of each thing yet, but definitely
   some. In any of the BNC spots, I can easily put an isolating type BNC,
   or a volume control pot. The front panel is mostly blank, so there's
   lots of room for even more stuff there. I just have to be careful to not
   get carried away and make it too wonderful and complicated and never
   finished.

   I also have an Efratom something-something distribution rack with five
   "MBF" modules that have four outputs each. They should pretty good too,
   but unfortunately it's all for 5 MHz only - there's low- or band-pass
   filtering built into each channel, so needs reverse engineering and mods
   for 10 MHz. I vaguely recall looking for info on this about a year ago,
   and stumbled upon an old time nuts thread. Someone (maybe Chuck Harris?)
   had reported successful mods for 10 MHz on these, but there were no
   links to any info about it. So Chuck, if you see this, and it was you,
   or anyone else, I'd sure appreciate this info. If it was just my
   imagination, then never mind.

   Ed

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