NimbleSig
III
Mounted
in a DieCast Aluminum Enclosure
I decided I would like to try mounting a NimbleSig III board in an
off-the-shelf diacast aluminum enclosure manufactured by Bud. This
enclosue used here is a Bud CU-124, Digikey 377-1108-ND with a
measurement specification of 4.37" X 2.37" X 1.21" inches
outside
dimensions. This box is oversized and you may be able to find a smaller
box in which the NS3 board will fit. I plan to install a shield plate
over the NS3 board and stack an application board on the top. I also
plan to install a 5V linear regulator and hope to find room to build in
an RS-232 interface. I plan to add text and photos to this page from
time-to-time.
20090402 UpDate:
Although NS3 runs OK in this die cast aluminum box version initial
tests indicate the performance is not as good as in the relatively RF
tight enclosure design described in my QEX article. The generator
outputs are not as clean and the power detector noise floor is quite a
bit higher. I think most of the noise being picked up by the power
level meter is probably RF hash from the built in RS232 converter but
further tests are needed to confirm that. However this method of
construction may still be OK for many applications. There is probably
several ways to improve the performance of this version and I am
interested in hearing feedback from others on how to do this.
73 de
Tom, VA7TA
Photo 1 : Top View of Bud Enclosure with Connectors and PC
Bourd Mounting Hardware
Photo 2 : Bottom View of Bud Enclosure with Connectors and PC
Bourd Mounting Hardware
Photo 3 : Aerial View of Bud Enclosure with Connectors and PC
Bourd Mounting Hardware
Photo 4 : PCB Rear Support Mounting Hardware
Photo 5: Preparation of PCB for Mounting
Photo 6: CloseUp View of LockWasher Spacer used with
FeedThrough Capacitor
Photo 7: PCB Mounted in Bud Enclosure
Photo 8: CloseUp View of the Connector PCB Interface.
Photo 9: View of the Populated PCB.
Photo10: View of the Populated PCB Now Mounted. Note the ground bonding
to the connectors and the wirewrap wire used for the external LED drive
and the Reset/Load Switches. A 7805 provides 5V from an unregulated 9V
DC supply.
Photo11: The feedthrough capacitor will provide +5V DC for an external active probe.
Photo12:
The shield plate is intened to isolate noise from the RS232 converter
and provide isolation for a possible future superhetrodyne 12 KHz BW
tracking detector in the future.
Photo13: The RS232 converter fits with room to spare over top of the shield plate.
Photo14: Finally the case is closed. This NS3 is calibrated and working.
Photo15: Since the NS3 PC board is burried externally accessable Load
and Reset switches are needed to accomodate firmware updates.
