[HBQRP] Meeting

[Darrel Swenson]

The instructions for the continuity probe are on page 10 of the August 
edition of QRPp.

The text of the article is below.  There are a couple of diagrams yahoo 
groups won't let me add.  They are in the articles in the files of 
either the qrp-tech Yahoo group or the norcalqrp group.

https://groups.yahoo.com/neo/groups/norcalqrp/files/2016%20QRPp/

https://groups.yahoo.com/neo/groups/qrp-tech/files/KI6DS/

The August KI6DS Kit, KI6DS Continuity Probe
by Doug Hendricks, KI6DS
I use a Harbor Freight VOM meter. The best thing about this meter is the
price. If you watch the Harbor Freight ads you can get a coupon to get a 
free meter. I
wondered about the accuracy, but don’t any more, as several of my 
friends have told
me that they have measured Harbor Freight meters and found them to be 
within 1-2%
of their Fluke meters. That’s close enough for the work I am doing, and 
I don’t have to
worry about dropping or stepping on my HFM, which I have done.
There is one problem with the HFM, there is no audible continuity tester.
love that feature and use it all the time. I don’t have to look at the 
meter when using
the audible continuity tester, I just listen!! So, I decided to design 
one. Ken LoCasale,
KI6DS Continuity Tester
QRPp V12#1 11
WA4MNT, came up with a very handy design for the QRP Guys Digital RF 
Probe, and
I borrowed parts of it for this design. Thank you Ken.
The circuit is very simple and there are only 4 parts on the board. A 
battery
holder, piezo speaker, spdt slide switch, and the brass probe itself. I 
layed it out using
Cirkad, and produced artwork to make my own board. See fig. 2. I am 
printing the
layout full scale and flipped, so all that you have to do is print it on 
shiny paper to
make your own board. In fact, I suggest this as a first board as it is 
very easy to do.
The parts placement is in Figure 1. After you etch the board, you can use a
pair of tin snips to cut out the board. Trim as close to the outline as 
you can. Then,
take some sand paper or a file and clean up the edges. It only takes a 
couple of
minutes. Don’t get too aggressive.
Parts List
1 - KI6DS Continuity Probe PCB
1 - SPDT Slide Switch (Ebay)
1 - 3.3V Piezo (Ebay)
1 - 2032 Size Battery Holder (EBay)
2 - #14 x #4 Ring Terminals
2 - 3/32” x 1.25” Brass Rods
1 - 2032 Battery
1 - 6” #22 Insulated Stranded Hookup Wire
1 - Shrink tubing
Construction
Step 1 - Inventory your parts. If you are missing something, let me 
know, I have extras.
Step 2 - Sharpen one end of each of the brass rods. I do it by chucking 
it into an
electric drill, placing it on some sand paper, and turn on the drill as 
I hold it at a 45
degree angle.
Step 3 - Solder one of the Ring terminals on to one of the brass rods. 
Set it aside.
Step 4 - Cut the ring off the other Ring Terminal and solder the sleeve 
on the other brass
rod, put the rod in about 1/8” and solder. Then take insulated wire, 
prepare the end for
soldering, and solder it into the sleeve of the rod. Let it cool, then 
put the shrink tubing
on and heat shrink it.
Step 5 - Solder in Switch 1
Step 6 - Solder in the Piezo, paying close attention to the polarity.
Step 7 - Solder in the Battery Holder, again paying attention the 
polarity. Orientate it
the same way as the drawing.
Step 8 - Using the #4 hardware, attach the main probe tip to the board. 
Put the Ring
Terminal on the same side of the board as the traces. Insert the #4 
screw from the other
side. Put the lock washer on, then the nut, and tighten. Line up the 
probe tip so that it
is parallel to the sides of the board as shown in Fig. 1. Now solder the 
slave of the
terminal to the board.
Step 9 - Insert the wire of the ground probe into the board. Solder the 
wire. Now bend
the wire flush with the top of the board, and cut off one of the 
resistor leads on the
QRPP V12#1 12
resistor provided. Use the resistor lead to make a strain relief and 
solder the other side.
Step 10 - Insert the battery into the battery holder. Make sure the 
polarity is right.
Positive goes up. Turn the switch to the on position. Touch the main 
probe tip to the
ground tip and you should hear a beep. If you do, congratulate yourself. 
If you don’t,
check your battery and piezo orientation.
Using the Continuity Probe
I find that I use it all the time to check solder joints on toroids. I 
put one end
of the probe on the first component down stream from the toroid, and the 
other on
ground, if the toroid is grounded, or on the next component downstream 
if it is not
grounded. Say Capacitor A goes to Toroid A then Capacitor B connects to 
the other
lead of the toroid. I would put the probe tip on the lead of Capacitor A 
nearest the
torroid, and the ground tip to the lead of the Capacitor B nearest the 
torroid. If I hear a
beep, I know the solder joint is good. If not, I fix it. Another use is 
checking for shorts
when you install connectors. Test probe goes to center conductor, ground 
probe goes to
shield. If you hear a beep, you have a short. I am sure that you will 
find other uses for
the Continuity Probe. One of the things I thought of was to paint the 
component side
bright red before I build the next probe, that way I can find it on my 
bench. Build your
probe and bring it to the next meeting. 72, Doug, KI6D