Norsat Ku Band LNA conversion for 10368 MHz

The page will provide comprehensive details for converting the Norsat 2000 series of Ku Band LNAs for Amateur use on 10,368 MHz. These are one of the easisest commercial KU Band LNA products to convert that I have seen. That being said, I will caution you on the machining that needs to be done to mount the SMA connector on the side panel. I STRONGLY recommend that this be done in a drill press so that you can be sure you are drilling straight holes at 90 degree angles to the LNA panels. You also need to be very careful to avoid damage when the drill bit breaks through the side wall. If you go too far, you will damage the PC board and possibly render the LNA useless. A good pair of vernier calipers is almost a must to get the SMA hole in just the right place. You can do it with a good ruler marked in 64ths on an inch but vernier calipers make the job much simpler and faster.

This first picture is of the complete unmodified unit. The case has been removed from the LNA itself but nothing else has been done. If your LNA does not look like this one, you may not be able to use these instructions. Even if it does, you may find minor differences inside so procede carefully.

Here is another picture of just the actual LNA unit. The case can be discarded since it will not be used following the conversion. Notice the metal tape, there are 3 pieces used on the LNA. You may choose to save and reuse it or just discard it. Also, look carefully at the top of the picture. The cover over the RF section has a thin sheet of embossed aluminum between the box and the sheet aluminum cover. I put this back in but it is not really required since it was orginally used to cover the RF section while adjusting the DRO frequency. You will find two screwdriver access holes in it. Since we disable the DRO, the acess is not required. I chose to leave but you can safely discard it in my opinion.

The picture is of the bottom section of the LNA. The bottom half from left to right is the DC section. Notice the wires coming in at the right through what was the "F" connector. There is a small coil visible near the top right corner just below a large diode, which is for reverse polarity protection. That is the DC power choke to seperate DC power from the IF signal going to the receiver. Remove the wire going from this choke and down to the "F" connector and then remove the connector. Solder a red wire onto that same terminal for incoming + 12 VDC power. Next solder a black ground wire to the trace under the screw next to the choke and feed it out the "F" connector hole with the red power lead. Notice the two wires in the lower left corner. They take negative and positive voltages to the RF deck. The white wire (sort of looks gray) is the Vcc while the blue wire is Vg.

The circle, just left of center marks the place where a trace needs to be cut to disable the DRO and mixer circuits. If you look closely, just to the right of center you will see a vertical trace coming up to a tee. To the right of the tee the trace has been removed where it goes towards the back of the LNA (to the right) just under the large round hole in the PC board. Do not damage the trace to the left side of the tee. The cover can be replaced once this trace has been cut and the power leads soldered in place.

Here is the business end of the LNA, the RF deck. Inside the sort of squashed diamond sahped compartment is the DC regulation and distribution for the individual active RF components. The white and blue wires can be seen coming from the DC side on the far right side of the squashed diamond section. Notice also that I used a small piece of the metal tape in the upper center of the RF deck. That was temporary since under it is a RF adsorbing material to control osciallations that is dropped into a slot before the cover is put in place. It will fall out and may get lost if you are not careful so I chose to keep it in place as I completed the conversion. That tape was removed before final re-assembly was done.

The left hand side is the mixer and filter coming from the third gain stage from the WR-75 input signal. The DRO is not visable in the LNA as it is underneath the DC circuit board. A short wire brings the LO signal up into the RF deck just above the second screw from the left along the bottom of the picture, just above the serpentine printed circuit choke and next to the RF adsorbing material on the corner.

To modify the RF deck sacrape off the portion of trace marked by the black bar and to the left of it in the third stage output filter that is an upside down "U" just to the right of the screw in the upper left hand corner of the PC board. Leave the portion inside of the vertical oval for later use. See picture below for more detailed after the fact information. Remove some of the LO drive traces (race track and open race track) to gain a little more distance from the traces we want to use. Next remove the PC board screw in the upper left corner of the above picture.

Scribe a line along the side wall (top in the above picture) just outside what remains of the filter you just modified. This line should be .204" down from the top surface that the cover bolts to. Draw a line from the top of the chassis (where cover fastens) straight down but in line with the trace inside the vertical oval. With a hand punch, very carefully punch a dimple where the two lines intersect and with a small drill bit (1/16" or smaller) drill a pilot hole. Be real careful when the bit punches through the inside wall that you stop drilling before hitting the PC board. If tyou are suing a drill press and are square to the chassis the bit will be above the PC board but non-the-less, be very careful. Next, with a #20 drill (.161") redrill the pilot hole. Be VERY careful when the bits break through the inside wall that you do not damage the PC board. This is the most likely time to destroy the LNA. Now insert the SMA female connector with the Teflon insulation into the .160" hole and make sure it clears. The center pin of the SMA connector should be just slightly above the PC board trace. If the Teflon protrudes past the chassis wall, remove some of it a with a very sharp utility knife being careful not to cut the center pin. Along the original horizontal trace that you first made .204" below the top of the chassis (where cover fastens) mark the two mounting holes for the SMA flange screws. Remove the SMA connector and drill two #50 (.070") holes at those marks. Tap them for 2:56 threads. As before, be VERY careful that you do not damage the PC board when drilling or tapping. Replace the screw removed from the upper left corner of the PC board.

Now bolt the SMA connector in with a pair of 2:56, 1/4" long bolts and tighten snuggly but don't over tighten or you will break the screws. Now that the SMA connector is firmly bolted in place, and the PC board screw has been replaced, solder the center conductor of the SMA to the PC trace being careful not to drag solder to the trace on the right. DO NOT SOLDER THE CENTER PIN BEFORE BOLTING THE SMA CONNECTOR FIRMLY IN PLACE! Additional notes are below the next picture so read them as well before proceding. The cover can be replaced at this point and the LNA tested. For the final step I pushed a piece of shrink tubing onto the power wires and forced it into the hole where the "F" connector was and then hit it with aheat gun. This will help protect the wires from chassis edges.

Here is the finished product ready to have the RF deck cover put back on. You can now also see the RF adsorbing material between stage 2 and stage 3 in the RF section since the metal tape has been removed. You can clearly see how I have trimmed some of the filter away from the left hand side of the SMA connector to avoid potential RF coupling of the 10 GHz signal into other circuits, even though they have been deactivated. I also removed some of the "C" shaped ring that brings in the LO power to the mixer circuit. The original IF signal passed through a small wire below the serpentine choke just below the "C" section for the LO signal. That wire is still there but does no harm so don't worry about it.

Notice how the SMA holes are drilled so that the center pin is just above the PC board for easy soldering. Also notice the Teflon around the SMA center pin. A hole was drilled to accomodate that to maintain a 50 ohm impedance through the chassis. I suggest a two hole mount SMA connetor making installation much simpler. This was my first conversion and without thinking I used 4:40 screws to mount the SMA, which was a bad idea. Only use 2:56 screws. I also used a right angle connector but a straight one is just as good.

Here is another one I converted using a different SMA connector. Other then the output connector, this on is identical to the one above. This is what the finished product looks like with the covers put back on; nice and neat and clean looking. The power leads come out the back in what was the "F" connector center pin hole. They have been protected with shrink tubing.

You are now ready to start hearing better on 10 GHz. Happy DXing!