Here's another reference on driving 10-ish MHz square wave outputs via
digital chips.
A few years ago I hacked my HP Z3816 to covert its 4 - 19.6608 MHz
square wave outputs to be 4 more 10 MHz outputs. In the process I
reverse engineered some of what was there. I found each of these outputs
came from one 74ACT040 inverter chip per output connector with several
gates in parallel through 100 ohm resistors to give low impedance drive.
Maybe all the parallel gates are overkill for most needs, but anyway, in
the process I drew a schematic of the arrangement that was found there.
You can find the schematic picture, labeled "One of the 19.6608 MHz
Outputs", near the middle of this page for the whole hacking project:
http://www.xertech.net/Projects/Z3816/3816_mod.html
Bob, I might add parenthetically, that while your responses always seem
accurate and informative, many times they are presented in such a
sketchy bullet-point way that only those who already understand what you
are describing can accurately follow what you are trying to share. Maybe
it is just my less-than-expert point of view, but I think a lot of your
posts would benefit if you could give a bit more detail or maybe a link
to some kind of example or explanation. I appreciate all you offer, it
takes time to read and reply, but I think often you are preaching to the
choir when a little more detail could reach the whole congregation.
Change or not, please keep posting. Even the cryptic stuff contains
meaning, perhaps a spur to dig deeper.
Bruce, when posting here, used to baffle me too, but he often shared
links to papers or schematics to aid in following the details of what he
was describing.
On 10/31/2014 5:02 PM, Bob Camp wrote:
Hi
A $0.15 each dual / quad / hex / octal buffer IC’s will get you > 15 dbm per
pair of gates. For under $10 in active parts you can have 30 or 40 outputs. I
suspect that if you look inside the 3812 that’s exactly how they are generating
the 10 MHz you are looking at.
Bob
On Oct 31, 2014, at 7:01 PM, Graham / KE9H <ke9h.gra...@gmail.com> wrote:
Bill:
On cable TV systems, 50 MHz to 500 (or higher) are the forward channel.
(Head-end to client.)
Below 30 MHz is the reverse channel, for data going from the client to the
cable company.
The band 30 to 50 is a cross over zone for the band splitting filters.
It is designed to not amplify the forward direction below 50 MHz.
--- Graham
==
On Fri, Oct 31, 2014 at 4:07 PM, Bill Riches <bill.ric...@verizon.net>
wrote:
Hi Bob,
I connected 10 MHZ test jack output to a 15 db el-cheepo CATV amp and the
output of that to a 4 way splitter. Splitter outputs went to 3336-3586 and
counter. All seem to like the ref signal. Output of the amp takes makes
the semi-square wave into a sick saw tooth. Amp is only rated from 50 to
500 mhz so strange things are happening with 10 MHZ input. Other CATV amps
do have better low fx response - will play with that later.
I have 10 mhz pulse from Lucent into trigger input of 465 scope and
Thunderbolt gps output into vertical input of scope. Time base is set for
.01 Usec per div. I notice that trace moves right to left then left to
right about every 5 min or so. Moves about 3 div before changing
directions. Why? Is the Lucent still making a list? It has only been on
for a few hours. It takes about 10 min for GPS to go out from a cold
start. (My Thunderbolt and RB do not change direction when using one as
trigger and the other for vert input to scope)
I ordered a USB to RS422 converter cable - will be here next week. What
program is sort of working? Using Windoze 7 64bit and have an old XP
machine available.
Sure do appreciate all the info from our time nuts gurus!
73,
Bill, WA2DVU
Cape May, NJ
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