While admiring my newly received divider board from David Partridge and
thinking about a suitable enclosure for its use on my bench, I happened to
look at an Extron ADA3 80 video distribution amplifier that I acquired after
suggestions from KO4BB. These enclosures are mechanically sturdy and quite
empty on the inside. There is plenty of room to mount the divider board
if existing (unused) threaded standoffs are relocated to match the divider
board mounting holes. As the distribution amplifier's circuit board and
connections are all on the back panel, the front panel is completely free and
clear for mounting the division ratio switch and output connectors.
The analog performance of the distribution amplifier seems very good;
however, the BNC output connectors are grounded to the case and there is only
one active output device for each of the R, G, & B outputs. The three
output connectors provided for each are simply isolated through resistors,
thus
isolation is limited. Nevertheless, for a single bench setup like mine,
the distribution amplifier will probably serve adequately well to distribute
10 MHz from a T-bolt to the counters, divider board, and a signal generator
-- all on the same bench. As the R, G, & B DA inputs can be looped, the
ADA3 80 can provide up to nine 10 MHz outputs via BNC connectors.
The ADA3 80 is powered from an external 9-volt, 500 ma wall wart.
According to KO4BB: _http://www.ko4bb.com/Timing/Distribution_Amp/_
(http://www.ko4bb.com/Timing/Distribution_Amp/) , the DA has an onboard
switching
converter and + and -5 volt regulators to power the distribution amplifiers.
It
is possible there is sufficient +5 volt current capacity to power the
divider board too. I have not investigated this yet as I am not certain about
the maximum current requirement for the divider board. Assuming it can be
powered from the existing supply, one could wind up with a very nice and
compact bench frequency reference and distribution system.
Extron rates the power consumption of the ADA3 80 at 2-watts. However, it
appears Extron uses the same PC board and power unit for the ADA3 180 for
which the power consumption is 3-watts.
Thus there may be adequate capacity to safely power the divider board.
If power supply noise is a problem, there is plenty of room in the case for
additional filtering.
Bruce Hunter, KG6OJI
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