The
Rockless QRP
Addendum-Corrections-Notices
Last
Up Date: 11/ 04/2010
Drawing Corrections:
It has been noticed that there is inconsistency in component
values between the circuit board and the schematic and parts placement drawings
supplied with early kit shippments.
Please take note of these Adjustments:
Capacitor
Values:
1.The capacitor from Pin 1 to ground on U3 should be 0.1
mfd.
2. the capacitor value going to the base of Q3 from the VFO
should
be 0.1 mfd.
3. The
correct value from U1, Pin 4 to ground is 0.01 mfd.
Resistor
Values:
1. Your kit
includes a 510 ohm resistor that may be used in place of the 1K
value shown as R19
NOTE
OF CAUTION ON RESISTOR CODES:
The 510 ohm
and the 1 meg ohm resistors have the same colors but
in reverse
order. Be sure to use 1 Meg at R4. The 510 ohm value at R4
will kill the receiver audio.
NOTE
REGARDING DIODE D6 IN SCHEMATIC:
Diode
D6 is drawn backwards on some schematic drawings that came with some board kits.
It is shown
correctly on the ARRL schematic found on the binary file for the
Rockless QRP. The Binaries are found at www.arrl.org/files/qst-binaries.
Diode D6 is
a 5 volt zener diode used to regulate voltage to U3.
MISSING OR WRONG PARTS IN KITS:
If any kit
arrives missing parts please email me immediately and I will send what was
missing.
I recently
found that a package that was marked 120 pfd was
actually 100 pfd. This was corrected
kits shipped after
KIT
SHIPPING SCHEDULE:
Most
kits have shipped. I am waiting for one part to complete the last of current
open orders. All orders
now received should ship within a week.
Caution When Wiring Multi-Turn Tuning Potentiometer:
Be sure to
check your 10 turn potentiometer with an ohm meter to determine which
connections
are the
ends of the 10K protion and which terminal is the wiper contact. The wiper contact should
go to the 100K resistor that connects
to the varactor diode. When measured against ground
the resistance at the wiper increases
with clockwise rotation. Likewise voltage to the varactor
diode should increase with clockwise rotation.of the control.
The higher the voltage to the
varactor, the lower the capacitance that it exhibits, hence
you tune up in frequency as capacitance
becomes
lower. Check this out before you get it all together.
Reported Source for MV209 Varactor
Diode:
K8RRH reports that he has found the
MV-209 Varactor diode for the VFO at the following
site:
Thanks K8RRH, this should be of great
help to many searching for this
part.
Search the site for diodes, “other” and you will find it.
VFO Inductor and VFO Stability:
I have had reports that when first
applying power to some oscillator boards, that the frequency drifts
for some time.
Recently I built an oscillator board using parts supplied in recently
shipped kits and
found this same problem. I have traced it to a substitute 8.2 uHY inductor used in the VFO which was
recommended as a replacement for the
original coil when I re-ordered the inductor. The coil in
question has multi-stripes, with gray
on the end and then red. (Color code for 8,2 uHY). The
original shielded inductors for this
value were all black in color and were very stable. Running a
sample test on on
the replacement coils I had in stock I found the substitute parts had poor
consistency of value and many were out of
tolerance. The original Black color
shielded coils all
test consistently in value and operate well in
the oscillator.
If you have trouble with oscillator
stability and your kit included the multi-striped coil, contact me at
rocklessqrp@comcast.net
and I will send you a replacement inductor.
I have recently changed this part
number in the Parts List to an unshielded 8.2 uHY
coil made by
Delevan.. The unshielded coil is
Delevan part 1025R-42K. It has a Digikey part number
of
DN7692-ND, and it is immediately
available in small quantities. Either
this unshielded 8.2 uHY
coil
by Delevan, or the Black color Delevan
Shielded coil give good stable operation in the oscillator.
The shielded inductor is Delevan Part
1641-822K. Mouser lists their part
number as 807-1641R-822K,
and this part appears to be immediately
available from them.
The unshielded coil is smaller in
diameter and is solid sandy yellow in color. The value is stamped
on it.
Kits shipped after 12/28/2009 will have either
the black shielded or sandy yellow colored
unshielded coils for the VFO.
Volume Control Suggestion
I have
found another Volume control that will ship with all future CK-1 kits. The 9mm square volume control
had been
used because it would fit in both size cases,
and at the time I couldn’t locate a better one to do the job
However, I have recently found Mouser Part number 313-1500F-1M. It has audio taper
and performs
very well in the Rockless. The body is about 16 mm (.63 inches) in
diameter, not counting the terminals,
which you can face to the side. The terminals are solder lugs. Remember to
short the center wiper to
one of the end lugs so that zero
resistance is in the full counter clockwise position.
Read this Great RF Probe Tutoral:
If you don’t already have an RF Probe
for testing your Rockless and other projects
involving RF, you can
find
a great tutorial for building one at
this web page: N5SE's Classic RF Probe Just click this link and it
will take you to the site. This is a simple item to build, which every
“building ham” should have in his shack.
The Article includes a great discussion
of how it works.
Alternative Audio Chip for LM1450:
The OP Amp chip LM 1450, 8 pin dip has
been getting difficult to locate. I have
found a substitute in
the Dual OP Amp KA4558. Mouser
stocks this chip as part number 512-KA4558.
No change in operation was observed
when using the KA4558 as the audio chip in the “Rockless Qrp”.
Setting the Offset Frequency:
It has been pointed out to me that I
mistakenly show the offset frequency in KHz rather than Hz as it should
be. Note that this has been corrected on the web
page under the Building Hints link for “Setting the Offset”.