MagicBox V1R2B User manual

Assembly Manual
V1R2B-Rev1.0D
for 4 State QRP
Mag cBox - Sol d State Transm t/Rece ve System
Designed by: Jim Kortge, K8IQY
Copyright 2009-2012 - A rights reserved
This system is the resu t of some brainstorming with Terry F etcher, WA0ITP and Joe Porter, W0MQY
at the Dayton Hamvention in 2009. We were ta king about kits that might be suitab e as revenue
generators to fund the Ozarkcon activities in 2010 and beyond. The "MagicBox" project is the resu t.
It is an a so id state, Transmit/Receive switching system that a ows one to connect sing e band CW
transmitters (up to a maximum of 10 watts) and receivers together to turn the pair into a transceiving
station, " ike magic". The system can be used on any band from 160 through 10 meters. It can hand e
both so id state and cathode keyed, tube transmitters. It supports fu QSK CW up to about 50 WPM.
And, a non-QSK mode is a so provided, for those who don't ike QSK CW.
There are five pieces of functiona ity within the system. First, is a keying circuit to turn on the
transmitter. Second, is a PIN diode switch used to connect the transmitter to the antenna so that it can
transmit and a so to iso ate the output impedance of the transmitter from oading the receiver. Third, is
a four e ement, series-shunt switch that disconnects the receiver from the antenna and shorts the
receiver input to ground whi e the transmitter is transmitting. Forth, is another series-shunt switch
(three e ements) used to disconnect the receive audio from the speaker (headphones) during transmit.
Fifth, is an sine wave audio osci ator and series switch that supp ies side tone audio to the speaker
(headphones) during transmit so that transmit keying can be monitored. A of the contro timing for
the system is supp ied from an AVR ATtiny2313 microprocessor.
1

The next pages contain an image of the supp ied printed circuit board and the schematics for the
system.
2

3

4

PCB Stuff ng
Stuffing the PCB wi be done by insta ing a of the connectors and headers. Fo owing that, a of the
resistors wi be insta ed, starting from the owest va ue and proceeding to the highest. Then, a of the
capacitors wi be insta ed, using the same scheme. That wi be fo owed by the inductors and
transformers, and then the diodes. When a of the passive parts are on the board, groups of integrated
circuits and transistors wi be insta ed fo owed by simp e tests to assure that circuits are active and
performing to specification. It is high y suggested that you print out both schematic sheets and use a
high ighter to mark each component as it is insta ed. This wi assist you ater on if you have parts eft
over and wonder where they were supposed to go.
Connectors and Headers
[ ] Start construction by insta ing Power Jack J1. Ho d this part toward the rear of the PCB so that is
projects out from beyond the edge of the board.
[ ] Insta the 4 audio jacks at ocations J5, J6, J8 and J9.
[ ] Insta the 3 BNC jacks at ocations J2, J3 and J4.
[ ] Insta a 2-pin header at ocations J7, J11, J12, J13 and J14. Supp ied with the kit is a break-a-way
20-pin header to be used for the 2-pin and the 3-pin headers. Use sharp diagona cutters or a hobby
razor saw to make the appropriate cuts.
[ ] Insta a 3-pin header at J10.
[ ] Insta the 20-pin IC socket at ocation U1. Make sure to get the orientation correct; match the
notch in the socket with that of the si kscreen over ay. Once it is so dered in, it cannot be removed
without destroying the printed circuit board.
5

Your PCB shou d ook ike this:
Res stors
[ ] Insta the arge, 1 watt, 180 Ohm (Brown-Grey-Brown) resistor at R12. This is the on y 1 watt
resistor; a of the others are 1/4 watt. Note: The eads of this resistor shou d be bent as
shown in this detai ed photo, so that it wi fit the ho e pattern and s ight y e evate the
resistor above the board for coo ing.
[ ] Insta 220 Ohm (Red-Red-Brown) resistors at R36, R43 and R44.
[ ] Insta 470 Ohm (Ye ow-Vio et-Brown) resistors at R3, R4, R14, R18, R35, R40, R42, R47 and
R48.
[ ] Insta 4.7K Ohm (Ye ow-Vio et-Red) resistors at R1, R2, R7, R8, R9, R11, R13, R15 (next to
R18), R16, R17, R20, R21, R22, R23, R24, R26, R27, R28, R29, R30, R31, R33, R34, R37, R38, R39,
R41, R45 and R49. Since there are so many resistors of this va ue, it is suggested that they be insta ed
in groups of 7, 7, 7 and then the remaining 8, shown by the co ored high ights.
[ ] Insta the 36K Ohm (Orange-B ue-Orange) resistor at R25.
[ ] Insta 47K Ohm (Ye ow-Vio et-Orange) resistors at R10 and R19.
[ ] Insta the 10M Ohm (Brown-B ack-B ue) resistor at R46.
6

[ ] Insta the 1K trimmer resistor (b ue potentiometer) at R32.
Your PCB shou d now ook ike this:
Capac tors
[ ] Insta 0.02 uF (green co or - marked 2A203K) at C19, C20 and C21.
[ ] Insta 0.1 uF (tan co or - marked 104) capacitors at C1, C5, C6, C7, C8, C9, C10, C11 and C12.
[ ] Insta 2.2 uF (b ack co or - marked 2u2) capacitors at C13, C22, C24 and C27. Note the + po arity
marking on these capacitors; they need to be insta ed with this + matching the + on the PCB.
[ ] Insta 22 uF (b ack co or - marked 22uF) capacitors at C2, C3, C4, C17 and C28. Note the +
po arity marking on these capacitors; they need to be insta ed with this + matching the + on the PCB.
[ ] Insta 33 uF (b ack co or - marked 33uF, 6.3v, non-po ar) capacitors at C25 and C26.
[ ] Insta 47 uF (b ack co or - marked 47uF, 6.3v, non-po ar) capacitors at C15, C16 and C23.
[ ] Capacitors for ocations C14 and C18 are not needed nor provided.
7

Your PCB shou d now ook ike this:
8

Inductors/Transformers
[ ] Insta 100 uH (beige co or - marked Brown-B ack-Brown) mo ded inductors at L1, L3 and L4.
These ook a bit ike fat, 1/4 watt resistors.
[ ] Wind and insta transformers T1 and T2. The "Winding T1 and T2" page contains notes on winding
these transformers, a ong with some photos of their construction.
Your PCB shou d now ook ike this:
9

D odes
[ ] Insta the 1N5818 (b ack body - marked 1N5818) diode at D1.
[ ] Insta the 1N459A (b ack body - marked 1N459A) diode at D2. Save one lead from this diode so
that it can be used as a jumper on the IC socket U1 later on in a testing stage.
[ ] Insta the 1N4007 (b ack body - marked 1N4007) diode at D3.
Your PCB shou d now ook ike this:
10

Regulators ( ook ike transistors with 3 eads)
[ ] Insta the 10 vo t (b ack body - marked 750L10C) regu ator at IC1.
[ ] Insta the 5 vo t (b ack body - marked 750L05C) regu ator at IC2.
[ ] Put the supp ied 2-pin shorting shunt on header J14. App y 12-15 vo ts DC to J1 and check that the
eft pad of R1 is at +5 vo ts and the eft pad of R25 is at +10 vo ts. A variation of +/- 0.25 vo ts is
acceptab e for each measurement.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
Your PCB shou d now ook ike this:
11

Trans stors
Transistors will be installed in groups so that testing can be performed. After successful testing, the
next group will be added. Using this approach will ensure that the completed project works as
designed.
[ ] Insta 2N3904 transistors at ocations Q14 and Q15.
[ ] Insta a 2N7000 transistor at ocation Q16. Note that 2N7000 transistors are sensitive to static, so
touch a meta object before picking up this type of transistor. Bui ding over a cookie tin is suggested as
a means of providing the meta object, p us it keeps parts from fa ing off of the work bench.
[ ] P ug a speaker or headphones into J6. App y power to J1 and confirm that a 700 Hz tone is coming
out of the speaker. Rotate trimmer resistor R32 through its fu range and confirm that the audio eve
changes from nothing to fu vo ume. This is a test of the side tone osci ator and its mute switch.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
[ ] Insta 2N7000 transistors at ocations Q11, Q12 and Q13.
[ ] Connect a test ead from the ower ead of R21 to ground. P ace a jumper (diode ead saved from an
ear ier step) from pin 20 to pin 16 on IC socket U1. P ug a speaker or headphones into J5 . App y
power to J1 and confirm that a 700 Hz tone from the side tone osci ator is coming out of the speaker.
This is a test of the audio muting switch when using the side tone osci ator as an audio source.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
[ ] Insta 2N7000 transistors at ocations Q1 and Q2.
[ ] Connect an antenna or other RF signa source to J3. Connect the antenna ead of a receiver to J2.
App y power to J1 and confirm that band noise or signa s from the signa source can be heard on the
receiver. This is a test of the series switches that connect the receiver to the antenna during receive.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
[ ] Insta 2N7000 transistors at ocations Q3 and Q6. These are the shunt switch e ements but won't be
tested unti ater system tests.
[ ] Insta a 2N3906 transistor at ocation Q9.
[ ] Insta 2N7000 transistors at ocations Q7 and Q10.
[ ] Connect an antenna or other RF signa source to J4. Connect the antenna ead of a receiver to J3.
App y power to J1 and confirm that band noise or signa s from the signa source can be heard on the
receiver. This is a test of the PIN diode switch that connects the transmitter to the antenna when
transmitting.
12

[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
[ ] Insta a 2N3906 transistor at ocation Q4.
[ ] Insta 2N7000 transistors at ocations Q5 and Q8.
[ ] Insta a 2N7000 transistor at ocation Q18.
[ ] Insta the IRF510 transistor at ocation Q17. The heat sink side of the transistor is away from the
1/8 inch audio jacks as shown on the PCB over ay.
Your PCB shou d now ook ike this:
Integrated C rcu ts
[ ] Insta the ATtiny2313 chip. Make sure that it is oriented to match the socket. Insta ing the chip
may require bending in the eads on the sides so that they ine up with the socket pins. To do this step,
put the chip on a hard surface on its side, and whi e pushing down on the chip, rock it toward the ead
ends. Repeat this operation on the other side. When the eads are 90 degrees to the body on each side,
it wi go into the socket with a sma amount of force.
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Operat onal Checks
If an RF Signa Generator is avai ab e, connect it to the Antenna Out BNC connector J3. If no signa
generator is avai ab e, connect an antenna to J3. Using a BNC jumper, connect the antenna ead of a
receiver to the Receiver Out connector J2. Connect a key to the Key(er) connector J8. Turn on the
receiver. App y power to the MagicBox. If using a signa generator, adjust the amp itude to 50 micro-
vo ts and tune the receiver to find this signa . If using an antenna, confirm that antenna noise is being
heard. Press the key and confirm that the signa into the receiver is great y attenuated. Remove power
from the MagicBox.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
P ace a shorting shunt on the 2-pin header J11. This p aces the MagicBox in Non-QSK mode. App y
power to the MagicBox. Press the key and confirm that the receiver returns to istening mode after an
approximate 1-second de ay. Remove power from the MagicBox. Remove the shunt and p ace it over
one of the pins for safe keeping.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
Continuing with the above setup, connect the audio output of the receiver to the Audio In jack J5. (Use
the wiring information on the “Connection Diagram” page for the receiver to MagicBox audio ead.)
Connect a speaker or headphones to the Speaker/Phones jack J6. App y power to the MagicBox. Turn
on the receiver and confirm that receive audio is coming out of the speaker/headphones. Press the key
and confirm that the audio signa from the receiver is cut off and the MagicBox side tone is being
heard. The side tone eve can be adjusted to a comfortab e istening eve with trimmer R32. Remove
power from the MagicBox.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
Remove the signa generator or antenna from the Antenna Out BNC connector J3. Turn off the
receiver. Remove the receiver antenna connection. Connect a dummy oad/watt meter to the Antenna
Out BNC J3 connector. Connect the RF output of the transmitter to the Transmit In BNC connector J4.
Connect the keying ead of the transmitter to the Transmit Key jack J9 of the MagicBox. App y power
to the MagicBox. Turn on the transmitter. Press the key and confirm that transmitted RF is being
shown on the watt meter. Turn off the transmitter. Remove power from the MagicBox.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
Continuing with the above setup, reconnect the receiver antenna to the Receiver Out BNC connector
J2. Turn on the receiver. App y power to the MagicBox. Turn on the transmitter. Key the transmitter
and confirm that RF is being shown on the watt meter and that the side tone is being heard from the
speaker.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
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With both receiver and transmitter connected to the MagicBox, key the transmitter severa times and
assure that the receiver is being muted except for the sidetone and the transmitter is keying proper y.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
Rep ace the dummy oad with a suitab e antenna and try the system on the air. Confirm that the
receiver is being muted except for the side tone and the transmitter is keying proper y.
[ ] Write down your resu ts/observations_________________________________________________
_________________________________________________________________________________
Th s completes the assembly and test ng of the Mag cBox. If you are go ng to operate t w thout a
case, put some rubber feet on the bottom of the PCB to keep t up off of the table so that
someth ng sn't nadvertently shorted out.
15

Connect on D agram
Note: The audio connection from the receiver shou d be wired to the MagicBox using a stereo p ug on
the MagicBox end, with the ground on the ring termina and the signa ead on the tip termina . The J5
and J6 jacks shou d have their mounting barre s insu ated from chassis ground with a 1/16 inch ength
of 1/4 inch shrink tubing over the mounting barre . No nut is used on either of these two jacks.
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Packag ng Cons derat ons
Now that you've comp eted your MagicBox T/R System, you may have decided to put it into some
kind of enc osure. This document wi aid your efforts in doing that. However, just so you know, it wi
work just fine without being in an enc osure; it was designed to work "out in the open" with just a set
of rubber feet attached to the bottom of the PCB so that the pads are not at risk of being shorted out.
That said, here is a run down of the various 2 and 3 pin headers that are on the PCB. They provide
convenient attachments for the various switches and disp ay LEDs that can be imp emented.
Header Funct on
J14 Connection point for a SPST N/O switch to turn power on and off.
J12 Connection point for a power indicator LED.
J7 Connection point for a SPST N/O switch to key the MagicBox, used for tuneup.
J13 Connection point for a "transmitting" indicator LED.
J10 Connection point for a SPST N/O switch to " eak" some receive audio to output jack J6
so that a receiver can be zero beat with the transmit frequency.
A togg e switch is recommended for the power off/on switch, but a atching push button switch cou d
a so be used.
The J7 and J10 switching functions can be imp emented in a variety of ways. A sing e DPDT ON-Off-
ON togg e switch (used on my prototype) cou d be used with the upper contacts used for the J7
connections, and the ower contacts used for the J10 connections. When using the J10 "spotting
function", the transmitter needs to be on, so the upper contacts wou d "make" when this switch is in
either direction from the center off position. If it is desired to not have the capabi ity of keying the
transmitter on and eaving both hands free, one cou d imp ement either or both of the J7 and J10
functions using momentary, push button switches or a togg e switch with momentary contacts at one or
both "ON" positions.
The MagicBox was designed to fit into a Ten Tec TP41 case. The MagicBox web site has a dri ing
temp ate on it, showing ocations and ho e sizes for the various BNC and 1/8 inch jacks that are on the
PCB, which can be used when insta ing the MagicBox in this case. Note that no mounting nuts are
used on 1/8 inch jacks J5 and J6. The ho es for these two jacks shou d be oversized enough to a ow a
1/16 inch piece of 1/4 inch diameter shrink tubing to be p aced over the shaft of these jacks, insu ating
them from the case. Any additiona ho e ocations and sizes for imp ementing the functions
documented above are eft to the bui der's discretion, since these wi vary wi d y depending on the
switches and LEDs used.
17

Mag cBox Spec f cat ons
General
System 160 through 10 meter operation
5.3" X 4.0 " PCB, fits TenTec TP-41 case
Approximate y 120 parts
Beginning bui der ski s eve project
Construction time approximate y 8 hours
Power Supply 10-15 vo ts dc; 120 mi iamps
RF Sect on
Rece ve Mode
Antenna to Receiver Input Loss: Less than 2 dB, 1.8 - 28 MHz
Transmitter to Receiver Input Iso ation: Greater than 25 dB, 1.8 - 28 MHz
Transm t Mode
Maximum transmit power Less than 10 watts
Transmitter Output to Antenna Loss: Less than 0.25 dB, 1.8 - 28 MHz
Antenna to Receiver Input Iso ation: Greater than 90 dB, 1.8 - 10 MHz
Greater than 85 dB, 14 MHz
Greater than 80 dB, 28 MHz
Aud o Sect on (32 Ohm source and oad)
Rece ve Mode
Receiver Audio Loss: Less than 2 dB
Transm t Mode
Receiver Audio Iso ation: Greater than 200 dB
Key ng
QSK Mode Up to 50 WPM
Non-QSK Mode 1 second receiver de ay
Transm tter Types So id state or cathode keyed tube
18

B ll of Mater al
19

Instruct ons for W nd ng T1 and T2
Start by marking each core with a "dot" on one end using a b ue "Sharpie" marking pen. Touch the spot
severa time to make sure that a permanent dot exists. This "dot" end by our convention wi be the
secondary side of each transformer, and have a 2-turn winding on it.
Start the secondary winding with a 3-inch piece of #28 wire, supp ied with the kit. P ace it in one of the
ho es, on the "dot" end of the core, eaving about 1-inch ead sticking out. Take the ead coming out the
opposite end, bend it around, and push it back through the other ho e. That's one turn. Repeat the
operation pushing the onger ead back through the ho e where you started, bending the ead around
again, and pushing it back through the opposite ho e. Snug up the windings by gent y pu ing on each
ead with a pair of sma p iers. The core with the secondary winding wi ook the the photo be ow.
If you ook at the end of the core opposite where the two eads exit, you shou d see two wires as shown
in the next photo.
Next, we have to add the 4-turn primary winding. This starts with a 5-inch piece of #28 wire. On the
opposite end of the core from where the secondary winding eads exit, push most of the wire through a
ho e, eaving about a 1-inch ead sticking out. As we did with the secondary winding, bend the free end
of this wire around and push it back through the core using the other ho e. That's 1-turn that we have
wound. Fo owing this examp e, repeat that process for 3 more turns. As you go a ong, try to keep the
windings tight within the core and aying organized and f at so that a of the turns can be added. When
you have the 4-turns on the core, it wi ook that the next photo.
Notice that the primary winding ead that was being pushed through the core ho es ends up about
twice as ong as the beginning end. That's a good check that 4-turns has been wound. Cut each of the
eads to about 1/2- inch, scrape off the insu ation, and tin the wire up to within 1/8-inch of the core.
The transformer is now ready to insta on the PCB. Repeat the process for the other core.
20