General Update: LPF and Amp Test Setup.

The LPF-140 Module provides the Low-Pass Filter Function from 160–10M. It is a 100W design using large inductors, heavy gauge wire and 500V Mica Capacitors.  Very particular attention is given to routing to maximize performance of the filter.

Artwork LPF-140R0

I decided to revise my first version with a new board size identical to the Amp Module. This Amp and LPF can be combined as a stacked set of boards. This will provide a more efficient packaging scheme. 

A set of test hardware is being assembled. It consists of the MPU, AMP with thermal block and heat sink and RF Path Module. Scrap sheet metal panels are used to simulate the eventual packaging mounted on a base plate.  My samples of SMA cables utilizing semi-rigid cable is not what we need in the amp. I have ordered all flexible RG174 internal cables as replacements. All internal cables use SMA connections. The thermal block attached to the amp and heat sink is a 1 x 1 x 2.25 inch aluminum block. No machine work is required on the new block design other than drill and tapped holes. It is cheaper than the machined part I originally envisioned. I ordered a couple blocks cut to length from standard stock. I expect this test setup to be ready for testing about 1 week from now as the ordered parts arrive.

Rather than design a package and try to make everything fit into it, the plan is to complete all the modules and then design the case. There should be less iterations in arriving at the final hardware.

Test fixture amp


As you can see, the MPU module is at the left mounted on the plate that isolates the computer section from the RF section. On the other side of the wall is the Amp Module. You can see the rectangle cutouts in the center of the board and the black heat sink below. The thermal block is not yet mounted. The LPF will be stack mounted above the amp. On the rear panel is the RF PATH Module. The PSU (power supply unit) mounts in blank space.

I appreciate all those with faith in the project who sent a deposit on the amp. These funds are used to construct the prototype and support the on-going R&D efforts. We need additional infusion from other builders to move the project along. Cash flow in the winter months has been traditionally low. Your help with the R&D expense would be greatly appreciated. I want to get the prototype LPF Module circuit board in the shop to complete the test setup. If you prepay a down payment of $200 you will be placed in the first delivery group as an incentive.

See a list of the builders who are on the list: File Attachment: 2011_HFSP V3 signup.pdf (65 KB)

See Expense Statement: File Attachment: HFSPP V3 Project 20111219.pdf (45 KB)

Merry Christmas and a Happy New Year!

73, K5OOR –  Virgil




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