The HCRA Rock-Mite Project
Everything related to the Rock-Mite building project will be located on this page.
NEW! – Pictures of the projects on Google’s Picasa Web Album. Click here to view.
|W1MSW||Matt||7030||Completed! Boxed and passed all tests|
|KB1PKJ||Mike||7030||Completed! Boxed and passed all tests|
|WB1DBY||Larry||7030||Completed! Boxed and passed all tests|
|KK1W||Jim||7030||Completed!||1st QSO on January 14th with VA3CWM|
|N1TOY||Mary||7030||Under Construction! PC Board Completed|
|KB1HZL||Fran||7030||Under Construction! PC Board Completed|
|N1NMO||Pete||7030||Completed & on the air!|
|KA1TDQ||Jon||3560||Completed! Check out the video!|
|N1FJ||Frandy||7030||Under Construction! PC Board Completed|
Hints & Kinks:
Are there more instructions?
When you received your kit it included a set of instructions from Small Wonder Labs. You should also download and print out the ‘Supplement to the ROCK-MITE Instructions’ from their website. I’ve put links to all the documentation above in the ‘Useful Links’ area. If you are new to kit building we strongly recommend NE1RD’s Assembly Manual – with this manual and some soldering skill (practice first) you should do just fine building your Rock-Mite.
What to do with those pesky ‘extra parts’?
Included with your kit was a small bag with two parts in it stapled to a piece of paper starting with the word “NOTICE:”. A few questions have come up concerning these two parts. They do not mount on the circuit board but actually connect between the antenna terminal on your case and the circuit board.
How to hold the SMD while soldering:
Here’s a tip from Fran complete with a picture on soldering this little bugger.
“I started the kit, and took a photo of the method I used to hold the smd ic to the pc board. This small clamp holds all the legs in place and in good contact with the board. I hope this is useful to the kit builders.”
What goes where and keeping track of your progress:
If you’re using Scott’s manual (and I hope you are!) the steps reference ‘figure 1’ in many places. Figure 1 is on page 5 but is pretty small. It is also somewhat inconvenient to keep flipping the pages back and forth while you’re working. I would suggest you use the drawing on page 3 of the instruction manual that came with your kit. It is the same drawing but is larger and on a separate page therefore making the task easier.
Another handy tip is to use a highlighter and mark off the components on the drawing as you install them in the board. It is a good way to keep track of your progress and serves as a ‘double check’ of your work. I suppose you could get real fancy and color each type of component differently (resistors, capacitors, diodes, etc.) but maybe that’s going a little to far!
Wiring to the controls and switches:
I crudely annotated the drawing on page 6 of the supplement manual to call out the wire colors used in Scott’s manual as well as remind you not to use the RG-174 but instead the ‘extra parts’ to connect to the BNC jack. Also there are many ways to run the ground wires between the jacks and switches. The drawing is one way, Scott’s is different physically but schematically the same. If you use the MityBox follow Scott’s instructions. If you elected to supply your own enclosure then do what you think is best.
You have a 50/50 chance of getting the gain control wiring correct (gray & white). If your volume goes down as you turn the control clockwise simply move the outside wire on the potentiometer to the other terminal, leave the center wire alone, just swap the outer one. If you don’t like those odds then use your multimeter set to ohms and pick the outside terminal that goes down in resistance as the control is rotated clockwise.
A few things to watch out for:
1. DON’T install R5 (on page 12) if you are going to use a gain (volume) control in your case. This is called out clearly on the page but is worth repeating. It will save you some de-soldering work.
2. Be careful when installing diodes D1 and D2 (on page 20). There is a set of unused holes just below D1. I might reverse the order of the manual and install D2 first, locating it in the set of holes just below U1 and to the left of the antenna. Then install D1 just below D2. Either way just don’t put anything in the bottom set of holes (looking at the board as in the drawing). These unused holes are in case you live close to an AM broadcast station and are experiencing interference. Page 10 of the ‘Supplement to Rock-Mite Instructions’ covers their use.
3. The 2.5″ length of RG-174/U coax cable included in your kit is not used if you follow Scott’s manual. This is OK, put it aside in your parts box (junque box) for future kits. Likewise the drawing on page 6 of the supplement is incorrect as it shows the BNC jack directly connected to the circuit board with the RG-174. Instead the BNC jack is wired with ordinary wire AND the two extra parts that came in your kit. See above (What to do with those ‘pesky’ extra parts) for the details and refer to the annotated drawing.
4. Color of L1, L2 & L3 is beige. Scott’s manual shows these as a light green color in the step-by-step on page 18. It looks like this batch of kits these inductors are beige, not light green. If you look at the picture of L2, L3 in the in the parts list on page 46 you will see the correct color. These are the only parts that look ‘something’ like a resistor but aren’t. If you’ve followed the manual by the time you get to installing the inductors there will be one resistor left (R5) and these three inductors. (remember, don’t install R5 UNLESS you’re not using a gain control). L1 is the big one, L2 and L3 are the small ones.
5. Watch out for C16! C16 is identical in size/shape/color to C5, C8, C14, C104, C109 and C110 EXCEPT it is a different value. When you’re sorting the capacitors find this one, it is labeled ‘102’, and separate it from the rest of the group. The writing is small, use a magnifier if necessary. The other 6 capacitors are marked ‘104’.
6. Parts list on page 44 is incorrect! The first line showing the .01 disc capacitor should reference C3, C13, C101,102 &108. There are only five (5) not six as shown in the quantity column. Refer to the parts list included with your kit to resolve any questions.
Concerned about the ‘how’ of kit building? Check out the fantastic ‘Heathkit style’ manual created by Scott, NE1RD. Download, read and/or print out this manual and the chance of a working Rock-Mite is virtually assured.
View or download your copy here.