[DSP-10] Initial turn on

[Richard Ewing]

George,

Pasted below is the doc that 7CQ authored.  Can't send attachments via this=
=20
reflector.

Again I hope this will help anyone in the completion phase of the DSp-10,=20
as &CQ and I had very similar test results and this was from the first TAPR=
=20
kitting.

73 O7N

DOC follows:

Initial Testing of DSP-10

This was taken from part 2 of the DSP-10 article in October 1999 QST page=20
39 by Bob Larkin  and modified by KO7N and W7CQ to fit the TAPR kitting.

For transceiver main-board alignment and basic troubleshooting, you need a=
=20
voltmeter. A signal generator covering 144-148 MHz is helpful, but=20
on-the-air signals are an adequate substitute and their use is assumed in=20
the following steps.

At this point check installation of U103 and U13 the small TO-92 5v=20
regulators installed in the middle of the DSP-10 main board to see if the=20
flat side faces the top of the board.  The silk-screen legends for these=20
two parts are backwards.

  First, apply +11 V to the main board without using the DSP board. At 11=20
V, it is not necessary to heat sink the voltage regulators, so the board=20
can be tested outside the box. At this point, current consumption should be=
=20
around 350 mA. If everything is operating properly, your checks should show=
=20
the nominal voltages given in Table 1. All dc voltages must be proper=20
before further testing is possible. If they=92re not right, find out why.

Table 1
Nominal Voltages
Component ID and Pin Number Function Vage (V)
U101 pin 1  10-V regulator input 11.0v
U101 pin 3  10-V Main regulator output 10.0v
U102 pin 3  5-V Main regulator 5.0v
U103 pin 3  126 MHz synthesizer 5v regulator 5.0v
U13 pin 3 19 MHz synthesizer 5v regulator 5.0v
U14 pins 2 and 13 Audio outputs 5.5v
Q106 pin 1 Receive line voltage 9.7v (if low (about 0v) see ** Receive=20
Line  Below )
U1 pin 3 First RF amp 3.5v  (Receive line must be High) **
U2 pin 3 Second RF amp 4.7v  (Receive line must be High) **
R110 Source of Q101 VCO 0.23v
U105 pin 3 VCO buffer 3.5v
U106 pin 3 VCO buffer 4.6v
R59 Source of Q4 VCO 0.91 to 1.8v  ( in this range somewhere )
U8 pin 3 VCO buffer 2.8v
U9 pin 3 VCO buffer 3.6v

** Receive Line:  Without EZLite installed and DSP-10 programming running=20
the Receive line may or may not be high (9.7v) as the main board powers up=
=20
in a random fashion. The Receive line can be easily measured to the right=20
of Q106 in series of holes were the silk-screen print says +10 R.

Next, mount the main board in the die-cast box and fasten the two regulator=
=20
heat sinks to the box. Connect the EZ-Kit box wiring, but leave the EZ-Kit=
=20
box separate from the main box so that it can be moved out of the way of=20
the main board. Connect the transceiver serial connection to the PC=92s=20
serial port using the 9-pin cable supplied with the EZ-Kit. Now both the=20
main board and the EZ-Kit can be powered via the power connector. With=20
power applied, load and run the EZ-Kit program UHF3.EXE as was done=20
earlier. Next, execute the PC program UHFA.EXE that initializes all the=20
parameters for the DSP program, including programming the synthesizers.

The amber POWER LED, D102, should be lit, but the red TRANSMIT LED, D103,=20
should be off.
Confirm the voltage readings at the following points:

Q106 pin 1 10 V receive 9.7 V
U10A pin 3 IF amplifier 6.0 V
U109B pin 6 Transmit IF driver 2.4 V

Set RF gain to 100  (press Shift-F8 on the PC keyboard)
Confirm the following voltages:

D2-A1 Antenna TR diode 0.73 V
D1-A1 RF Filter TR diode 0.73 V
These voltages will drop as the RF gain is lowered from 100, first in D2-A1=
=20
and then in D1-A1 as the RF gain is lowered even more.





Measure the 19.68-MHz synthesizer tuning voltage at the U6 pin 6 side of=20
R54 (Figure 8). Set this to about 4 V using C69. If it is not possible to=20
set the voltage to that level, adjust the turns on the VCO coil, L21.
Pushing the turns together raises the tuning voltage. After you are sure=20
that L21 is at its proper setting, use a small dab of RTV sealant to hold=20
the windings in place and secure the coil to the board.

  Set the MODE to CW (press ALT-M on the PC Keyboard) and use the keyboard=
=20
to set the Operating Frequency to 147.000 MHz.  Ensure that a jumper is in=
=20
place between pins 1 and 2 of P106, or that an external reference signal is=
=20
being fed to P106 pins 2 and 3.  Adjust the 126- to 128-MHz VCO coil, L102,=
=20
until the tuning voltage measured at the junction of R104 and R105 is about=
=20
3.5 v.

If you have a counter, probe the right side of C127 (where the silk-screen=
=20
legend reads 126 MHz LO) this will show a frequency of 127.335 MHz when=20
operating frequency is set to 147.000 MHz and the PLL is locked.  When the=
=20
PLL is locked the incessant beep / beep from the computer every .6 seconds=
=20
will stop.  We found it necessary with the TAPER kits to lower the value of=
=20
C117 to 6.8pf  (from 10pf) to get L102 into the center range of 126 MHz. As=
=20
supplied L102 resonates LOW in frequency even with the core fully out it=20
could barely get high enough in frequency to lock at the low end of the=20
band before we changing the value of C117.  Now the core is centered in the=
=20
L102.

If you are having problems obtaining full PLL locking range from just below=
=20
144MHz to just above 148MHz you can increase the value of C141.  Just add=20
few pf across C141 will do to increase the width of the locking range.  If=
=20
you lower the value of C141 your locking range of the PLL will=20
narrow.  With the supplied value of C141 (10pf) our PLL will hold lock from=
=20
143.200 to 148.500 covering the US 2 meter band very nicely.

Attach an antenna and see if you can receive a local repeater signal, with=
=20
the transceiver in CW mode. If so, adjust the 10 MHz internal=20
reference-oscillator frequency with C110 until the carrier pitch is about=20
600 Hz with the repeater frequency on the display. If it is not possible to=
=20
get on frequency adjusting C110, change the value of C109. As you obtain=20
more-accurate frequency references than a local repeater, it will be=20
necessary to repeat this adjustment.
OR:
If you have or can borrow an ACCURATE frequency counter you can read the 10=
=20
MHz reference-oscillator frequency at the left side of R150 (this is the=20
same as pin 2 U104 but pin 2 is very hard to probe safely. We found that=20
the Epson crystal supplied with the TAPR kits run High in frequency and=20
adjusting C110 would not get the frequency down to 10.000 000 MHz.  It was=
=20
necessary to increase the values of C109 and C108. We changed C109 to 22=20
pf  (had some extra 22pf caps from building the Brickette) or you could add=
=20
a 10pf in parallel with the 10pf cap already there) and added around 10 pf=
=20
( =B13pf ) in parallel C108 to resonate at 10.000 000 MHz with C110.   The=
=20
caps added parallel to C108 may require a little tweaking as both of our=20
units required different values across C108 to get into range of 10MHz with=
=20
adjusting C110.

Next, peak crystal-filter coils L12 and L13 for maximum signal. The=20
signal-level indication can be helpful for these adjustments. Select a=20
repeater frequency as close as possible to 147 MHz and peak the RF filter=20
coils L1, L2, L8, L9, L10 and L11 at that frequency. Now, center the MIKE=20
GAIN R124. That completes all adjustments.

Connect a dummy load to the antenna connector (a 51-., 1/4-W resistor is=20
adequate) and press the Home key to put the transceiver into transmit. With=
=20
the key up, you should measure the following voltages:

D1-A2 RF Filter TR diode 0.73 V
U4 pin 3 1st transmit amplifier 3.6 V
U5 pin 3 2nd transmit amplifier 4.6 V
Q2 emitter Power-amplifier emitter 1.2 V
Q2 base Power-amplifier base 1.9 V

While holding down the CW key (righthand ALT key), measure the=20
transceiver=92s output power. At this point you should be hearing the cw=20
sidetone in the speakers with the righthand ALT key is pressed.  If NOT you=
=20
probably have the DAC L and DAC R lines reversed from C218 and C219 to the=
=20
J2 jack on the EZLite board and if they are reversed the transmitter=20
section will not put out any signal or power.  An other receiver set to the=
=20
tx output frequency is a good way to see if any signal is there.

It should be at least 20 mW at full-power screen setting of  ( Xmit=20
Pwr    100 )   Figure 12 shows a circuit that can be used to measure the=20
power output if a power meter is not available.


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