Category: Kits and things

The RX op amp/output stage is another relatively easy one. A handful of non-band specific through hole parts, 3 SMD caps and the SMD op amp. Nothing too difficult here, although again, you’re dealing with pretty tight quarters with the through hole parts.

The line-in (which goes to the line in port on your computer’s sound card) is the largest component to deal with.

The instructions for wiring JP2 in the build instructions were a bit confusing. My interpretation was that if your jumpers crossed over (jumper wires formed an X), then you could use any of the software mentioned (PowerSDR, Rocky, Winrad). In this configuration, you’d need to set a “Swap IQ” setting in Rocky/Winrad. If the jumpers were straight across, you could use Rocky or Winrad, but not PowerSDR.

I chose to jumper them straight across as shown in the WB5RVZ build instructions.

Top of the board for this section.

Bottom of the board

Next section is the TX op amp. Lots of parts there.

The RF mixer section is a pretty easy section with only 4 through hole parts and 2 SMD. Nothing terribly complicated here.

If you’re doing the build over an extended period of time like I am and following the WB5RVZ build instructions, make sure to double check the band selection before each build session.

Two capacitors and two resistors (band specific) are added to the top of the board.

On the bottom of the board, the only thing to watch out for is the orientation of the FST3253 IC.

RX op amp stage is next.

Finishing off the RF I/O stage means winding 3 toroids and two transformers on relatively smallish cores (T37, T25 and a BN-2402).

(Those are T30 cores in the picture…accidentally grabbed those instead of the T37 cores)

Took me about an hour to wind all the cores and get them soldered onto the board. For the transformers, I think I spent more time checking and rechecking the leads to make sure I had the primaries and secondaries sorted out properly.

Four bifilar turns is a lot to stuff into a BN-2402 core. It was a pretty tight fit with the AWG30 wire but I was able to cram it in.

With the toroids and transformers soldered onto the board (yay for heat stripable magnet wire!), this is what the top of that section looks like now.

Mixer stage is next.

Started on the non-toroid/transformer parts of the RF I/O and switching section of the build. Nothing too difficult with this section. Four SMD capacitors on the back of the board. On top are through-hole resistors, caps, and transistors.

The holes for the transistors is pretty close together, so to make inserting them (TO-92 package) easier, use some needle nose pliers to straighten out the outer legs. The transistors slip right into the holes without having to force them in because of the bend in the leads.

The BNC connector is also attached to the board at this stage. The one supplied with my kit has an all metal body. Soldering the two ground pins to the board takes a lot of heat. I ended up having to hold my soldering iron on the pins for close to a minute before they got hot enough to get a good solder joint. I suggest doing the BNC connector last. Once you’ve got it soldered on, it stays pretty hot for a while.

Top and bottom of this section so far.

Off to go wind some toroids and transformers.

On to the dividers stage of the build. Only 4 components here: a 74AC74 dual flip flop, a SMD cap and two resistors. The pin spacing on the 74AC74 is relatively wide, so it’s pretty easy to solder. The blob and wick method will work, but it’s also pretty easy to do each pin individually. Just have to make sure you get the orientation correct.

Top and bottom of the divider section of the build.

Here’s the top and bottom of the whole board so far.

Next up is the RF I/O and Switching stage. Lots of stuff in that stage including a bunch of toroids and transformers, so that will probably take me a couple of days to do.