Gang,
I'm late with errata for the Rainbow articles that appeared in
December QRPp and January QRP. Working on the NJQRP Rainbow kit
manual had to take priority. You will be pleased with the
manual when you see it!
This errata list is a composite of one I posted earlier with
additions by Dave Meacham W6EMD and others. Gosh, folks really
read this stuff and try to understand it! The corrections that
have page numbers indicated refer to the QRP Quarterly pagination
(like that word?). The same corrections apply to the QRPp
version. It is left up to the interested reader to figure out
the page numbers!
1.) In the wiring diagram at the bottom of Page 33, the left-hand
battery terminal should be marked "B-", not "B+". In the same
diagram, The "ANT GND" pin should be marked "E9" and the "ANT"
terminal is "E10". For clarity, the "50 OHM" terminal E12 should
be shown as the coaxial shield ground.
2.) C18 is missing from the Parts List on Page 34. It is a 200K,
1% resistor and is correctly shown in the schematic diagram.
3.) 15 "T44" pins are shown in the Parts List while only 13 are
used on the circuit board.
3.) In the schematic diagram, there are four capacitors marked
C1. Fortunately, though, the capacitance values shown are right.
C1 is *really* the one at the cathode of D1. The capacitor at
the drain of Q1 should be marked C6, the bypass capacitor on U1
pin 3 is really C7 and the variable trimmer cap is C8.
4.) The parts list shows L1 as just the core and 40 inches of
magnet wire are called out. Coil winding details were left out.
The coil consists of 30 turns of magnet wire with taps a 3, 4, 6
and 8 turns from the ground end of the coil. the 40 inches of
wire is overkill, but it's always best to start out with too much
rather than too little!
5.) R5 is 51 Ohms in the schematic, but 10k in the parts list.
Of course it should be 10 k ohms since it is a dc decoupling
resistor. Hint, look at the other side of the bridge. Since
there is intentional symmetry, it is the same value as R4.
6.) R11 is 150k in the schematic, but 10k in the parts list. It
should be 150 K ohms.
7.) S1 in the external wiring diagram is suggested so that you
can switch the bridge in and out. I didn't have a small enough
switch to fit in my Altoids tin so the prototype in the photos
doesn't have one.
8.) In the parts list I indicated the source of may parts. DK
stand for DigiKey, RS stands for Radio Shack and DSP is not a
means of applying computer techniques to weak signal reception,
but a reference to Dan's Small Parts.
9.) C7 in the parts list should be C8.
All right now that you know these corrections, just be forewarned
that there are a few circuit changes the kit Rainbow schematic
diagram and coil winding instructions. So if you try to compare
the manual with the articles, don't be confused.
Speaking of the kit, shipping will begin later this week!
72/73,
Joe E., N2CX
72/73,
Joe E., N2CX
from Southern New Jersey, y'all
work: jeverhart@cayman.vf.mmc.com
home: n2cx@voicenet.com
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