QRPGuys Multi Z User manual
Page 1 of 13 multi_assy_053019.pdf
QRPGuys Multi Z Tuner Assembly Manual
First, familiarize yourself with the parts and check for all the components. If a part is missing, please
contact us and we will send one. You must use [email protected] to request a part.
Parts List
1 – QRPGuys Multi-Tuner PCB, 5 pieces
2 – S2, S3 - Slide switch – DPDT
1 – S1 - Slide switch – DPDT, 90º
2 – C2, C3 - Polyvaricon, w/shaft and hardware, 1 long, 2 short metric screws, and nylon spacer 3/8”L
1 – C1 - .1uF mono capacitor, marked 104
1 – D1 - Red LED w/clear lens
1 – D2 - 1N4148 signal diode, sm. glass, w/black band on one end
3 – R1, R2, R3 - 51 ohm 2W power resistor (green-brown-black-gold)
1 – R4 - 470 ohm resistor (yellow-violet-brown-gold)
1 – L1 - FT37-43 toroid core (black)
1 – T1 – T106-2 toroid core (red)
1 – 24” of 26AWG magnet wire
1 – 6’ of 20AWG magnet wire
2 – #2 size control knob
2 - BNC PCB horizontal connector
2 – 8-32 x 3/4”L SS Phillips pan head screw
4 – 8-32 SS nut
2 – #8 internal tooth SS lock washer
2 – 8-32 SS wing nut
1 – 4-40 x 1/2” long nylon screw
1 – 4-40 nylon nut
1 – 3/8” diameter #4 nylon washer
4 – Round self-adhesive rubber foot
1 - 4-40 x 7/8”L SS pan head screw
1 - 4-40 SS nylon insert lock nut
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First item to assemble is the PCB chassis.
Even if you have done radio kit assembly before, please read through all the instructions before you
start. This kit is a little different, in that the mechanical components are the part of the printed circuit
board. The instructions give you the scope of the project and an understanding of the techniques we
have employed. You will be assembling the kit from five pieces of PCB material. The base contains all
the circuitry for the tuner. There are solder pads, and letter coded parts, that match each other. When
you tack and then solder the components it will make a sturdy mechanical assembly.
Refer to the figure below for identification of the individual PCB parts.
On all the mechanical assembly soldering you do, you will use the same technique. You
tack a single tiny point first, and then check to see that it is square and aligned with the
registration points and assembly notes. It is easy to re-heat the joint and adjust the
alignment when there is only a single point. You will tack all the other pads, before you
do the finish soldering.
When soldered, the completed chassis will look like this, with all the holes and circuitry needed for the
assembly. There will be no drilled holes to be added.
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Soldering the chassis together:
One of the physical properties of solder is that it contracts when it cools. Knowing this, we can allow for
it. If two pieces of the pcb material are clamped 90° apart, and you apply solder at the joint, the joint will
close about 1°-2°, no matter how well you clamp it, the PCB material will flex and you will end up with
an 88° corner. That doesn’t sound like a lot, but you don’t want that to happen. If you try to straighten it
cold, you will lift off the solder pad from the PCB. To counteract this, you position the front panel at
slightly greater than 90º. When it’s tacked it will pull back to square (90º). Finally, adding the gussets
maintain this position and make a strong assembly.
You will need to work on a flat surface. I use a 1 foot square piece of a Formica counter top, but any flat
surface will do. The first task is to position the front panel and the base with the “C’s” matching, so that
both side edges are flush with each other against something you have that is square. It can be a small
piece of angle iron, or a square piece of wood with sharp corners. Position a short piece of 1/32”
diameter solder or wire 4” long against the bottom of the square corner and lean the front panel back.
This gives you the greater than 90º you are looking for. See figures below.
[ ] A small “tack” at one of the “C” pads is all that is required at this time. Check for squareness,
flush on both sides, and flush on the bottom. If not all these conditions are met you only have to
reheat the one tack and reposition the two pieces. When you are satisfied, “tack” the other “C”
pad. Do not completely solder the pads.
Position either of the side gussets against the inside edge of the previous assembly. Match the letters.
You can hold the small triangle of PCB material while you put a small “tack” on one of the pads. As
before, check for squareness, and a flush joint. See the figure below.
[ ] “Tack” the other pad on that side. Do not completely solder the pads.
[ ] Use the same technique with the other gusset.
[ ] When you are satisfied with the alignment and squareness of the “tacked” assembly you can go
back and complete the soldering of all the pads. Alternate between different pads and add a
small amount on each pad until the joints are complete.
This completes the chassis.
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Now that the chassis is complete. Refer to the graphic below and the silk screening for the placement
of the components.
[ ] Install S1, so the operating lever passes through the front panel.
[ ] Install C1, .1uF mono capacitor, marked 104.
[ ] Install D2, 1N4148 signal diode, observing the black polarity band (cathode) location as shown
in the figure below.
[ ] Install R4, 470 ohm resistor (yellow-violet-brown-gold)
[ ] Install R1 – R3, 51 ohm, 2W, power resistors (green-brown-black-gold), or value is printed on
the component.
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[ ] Install the clear lens LED protruding thru the front panel into the hole just over the S1 switch
position. First, bend the leads as shown below 7/16’ from the back of the LED. The polarity must
be correct. The short lead is “negative” and goes towards the right side of the chassis. The long
lead to the left pad.
[ ] For L1, use the FT37-43 (black) core and the 24” of the thinner supplied magnet wire. You are
winding a total of 25 turns, with a tap at 5 turns from the beginning of winding. Remember, every
time the wire goes through the center of the core, it counts as one turn. The picture and figure
below shows the beginning of winding and the twisted technique for the tap. The total of 25
turns will completely fill the toroid. Don’t wind it loose, a #4 screw must go through the center for
securing.
Note: Now is a good time to mention a good way for counting the turns on small toroids. Many times on
toroids with a lot of turns, you lose track going around. A good trick is to take a digital picture of it and
blow it up on your computer screen. Counting is clearly a lot easier. Never cut until you verify the turn
count. Too many turns is easy to fix, too few leaves only one option..
[ ] Bend the leads as shown below, trim to 1/4” long, and tin the leads prior to soldering them
to the backside of the board. The magnet wire supplied Is Thermaleze® brand and will tin easily
with a soldering iron. Always tin the leads before trying to solder them in place and you will
greatly eliminate any continuity problems.
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[ ] Solder L1 where indicated on the PCB, and centered on the screw hole. You will notice the tap
hole is indicated, and is slightly larger in diameter to accept the double twisted wire. Install the
toroid flush with the backside of the board. Do not elevate it off the board. You will be securing it
with a nylon screw, nylon washer and nut.
[ ] Secure L1 to the top of the board using the 4-40 nylon screw, nylon washer, and nylon nut, as
shown below, with the screw from the bottom. Tighten enough to secure and protect the toroid,
but do not over tighten.
[ ] Install the two BNC connectors flush with the top of the board, and solder the two locating
pins and two electrical connections.
[ ] Install the two remaining slide switches at the places indicated, soldering all four corners and
electrical pins.
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Poly varicon installation to kits ordered before 01/20/18
[ ] Prior to installing the poly-varicon variable capacitors the leads must be re-routed through the
snap-on cover. The pictures below show the “as received” and “modified” condition. Carefully
pry off the cover, bend the leads to the rear, feed them through the cover and snap it back on.
There is a small tab, opposite the side with the leads, on the cover that matches the body of the
poly-varicon for the cover to fit properly.
As received Modified
[ ] Adjust the two trimmer caps on the back of each poly-varicon to their minimum value as shown
below.
[ ] Install the two polyvaricon capacitors on the inside of the front panel. Carefully feed the three
leads through the board and secure the capacitors with the two short metric Phillips screws from
the outside. Solder and clip the leads flush. Install the nylon spacers, long metric screws, and
knobs as shown in the figure below.
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Polyvaricon installation to kits ordered after 01/20/18
As received Modified
The polyvaricons as received, need a modification to allow the leads to reach the bottom of the device
so it can be soldered to the pcb. If bent without modifying the cover, all the leads will not reach. Shown
above is the un-modified polyvaricon as received.
Carefully unsnap the protective cover. Deepen all three slots for the connection tabs by ~1/8” with an
Exacto knife as shown on the right. Snap the cover back on, and run the leads on the outside of the
cover.
Shown below the modified cover is snapped back on and the leads are bent to the bottom. It is now
ready for installation. As you can see, one of the leads is shorter than the others and may need to be
soldered on the top of the board. This is not a problem with plated through holes.
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[ ] Adjust the two trimmer caps on the back of each poly-varicon to their minimum value as shown
below.
[ ] Install the two polyvaricon capacitors on the inside of the front panel. Carefully feed the three
leads through the board and secure the capacitors with the two short metric Phillips screws from
the outside. Solder and clip the leads flush. Install the nylon spacers, long metric screws, and
knobs as shown in the figure below. One of the leads is shorter than the others and may need to
be soldered on the top of the board. This is not a problem with plated through holes.
[ ] Install the hardware posts for the antenna wires, as shown in the figure below. The post screw
should be flush with the outside of the securing nut on the back side.
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T1 assembly
The next item to make and install is T1. This T106-2 toroid has a 16 turn center tapped primary, a 12
turn secondary, and another 6 turn secondary. We have supplied a 6 foot length of 20awg magnet wire
for this purpose. Proper winding of the transformer will result in the three different windings ending up at
the correct positions on the PCB. The two secondary windings are on top of the primary winding. The
graphic below shows the separate windings and how they are positioned on the T160-2 toroid. Please
study the following figures and understand the process before you try winding the transformer.
If a winding does not end up as shown below or is not wound in the same direction as shown
below, the tuner will not work properly. Note that the ends of the windings must be over or
under the core as shown below.
The seven pad positions for T1
[ ] Prepare the primary wire as shown in the figure below. Cut 30” of the supplied 20awg wire and
a 2” piece. Strip the insulation off of the 2” piece for 1/4” and make a small loop that will attach
to the center of the 30” long section. On the 30” piece measure to the center (15”) and strip off
the enamel insulation for 1/8” inch and solder the loop to the center. See photos below.
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