n9ik’s radio blog

Well, the BLT kit finally arrived yesterday. Yippee! I did a parts inventory last night, and found some discrepancies from what the documentation says should be there.

• R4=1 K ohm 1/4 Watt resister. Received a 410 ohm resistor.
• 4 rubber feet. Missing.
• 8 1/4″ x 4-40 undercut flathead screws. Missing.  But, I think this is due to there being a different enclosure than shown in the docs.

A couple of other gotchas:

• The enclosure is different from that pictured in the documentation. It is a little dirty and is scratched from the bending process.
• The PCB has “hair” – fiberglass fibers at least an 1/8th inch long – along the edges. It needs to be sanded off.

A good plus:

• The extra parts are included and the enclosure is already drilled for the “mod” that adds the ability to use a coax feed line or a balanced line antenna, and not just a balanced line feed. Great! I was planning on doing this mod anyway.

It turns out that aside from the missing rubber feet, I do have all of the appropriate parts. Here’s what Doug said in his email to me:

Thor, the parts list has not been updated to match the new enclosure. The 70 ohm resistor is an improvement over the 1K as it makes the LED righter and easier to see.

By the way, the price is going to go up on the kit soon due to the improvements and additions of the switch and the extra BNC. Also the new case is bigger and easier to work with. Please let me know what you thin of the changes.

Thanks Doug

As for the case, I think I’ll paint it anyway, and I can easily find appropriate rubber feet locally. And if I didn’t paint it, it would probably get pretty beat up looking in time anyway, since I don’t exactly use kid gloves with portable gear. I look forward to getting this kit built and to put it to use. Updates to follow.

I’ve finally gotten around to completing the Rock-Mite 40 transceiver kit. It was fun to put together, in spite of my problems with my shaking hands and the difficulty it causes with putting components and wires on the board and connectors. Below are a few photos:

The RM board is fully “stuffed”, waiting for wires.

In this picture of the RM at board level, you can see that I’ve used SIP sockets as sockets for the crystals, allowing me to change out the crystals with 7.040 MHz crystals, which are for the other 40meter QRP calling frequency.

Another board level close-up.

Here some of the wires have been added.  The crystals have been removed, and you can clearly see the SIP sockets at lower left and upper right on the board.

To fit the FCC’s newer (June 2004) spurious emission requirement, a 150pF cap and a 3.3 uH RF choke should be installed in series between the center conductor of the antenna connector and the board. The RF choke lead would not fit through the through-hole on the board, so I soldered it directly to the antenna connector, and put the capacitor on the board. The antenna connector and the caps position on the board are close enough that the leads of the choke and capacitor can be soldered directly together with out using the coax. Eventually, I ended up breaking the lead off of the choke, and since I don’t have a replacement I removed it and the cap and used coax to connect the board to the antenna connector. I’ll put the choke and cap back on when I can.

It’s a tight fit with the board and connectors all wired and installed in the Mighty Box enclosure. Here you can see that the leads for the two crystals (lower left and upper right) needed to be bent over so that the crystals would fit. If they had been soldered directly to the board instead of using sockets, they would probably have been fine standing up straight.

Ready for the bottom cover to be screwed into place.

Front view of the completed RockMite. Left to right, audio gain, switch, phones. The switch is used to toggle off-set frequency and control the internal keyer.

Rear view of the completed RockMite. Left to right: key, antenna, power.

If/when I get a clear label cartridge for my Brother P-Touch labeler, I will add labels to the RM case.

Now, to make some contacts!