By now, I hope you understand that you really should get a manual for the Exec II.
But, some of you will want to try to do it without one. To be honest, I've
tuned a VHF version with only experience from the UHF version. So I guess
there are times that a few hints might be enough.
As time permits, I'll add tuning information on various parts.
First some general advice about tuning:
There's a sort of Zen thing about tuning Mastr II receivers. I've often hit
the wall on sensitivity after following the procedure perfectly again and again.
I intentionally detune every control to just some random position. Then I got
to bed.
The next day I start over, step by step. Only this time the voltages are a
bit higher... then as you get to the later stages the voltages are much higher.
Then everything falls into place and you have a great receiver. You'll swear you
did it right the first time, and you probably did. But a night's sleep has fixed
so many receivers I swear by this method.
UHF Exciter Tuning
Preliminary Checks and Adjustments.
1. Place crystal modules for F1 on Exciter Board. (crystal
frequency = operating frequency / 36).
2. For a large change in frequency or a badly mis-aligned
transmitter, preset all slugs to the top of the coil form.
3. Set output impedance matching capacitor to 1/4 mesh.
4. Set all other air capacitors to minimum capacity (not meshed).
5. (applies to multi-channel situations, not applicable with a
repeater setup)
6. Connect the red plug on the GE Test Set to the SAS Board
metering jack, and the black plug to the exciter metering jack. Set the polarity to
+, and set the range to the Test 1 position (1 Volt position for 4EX8K12) for all
adjustments.
7. All adjustments are made with the transmitter keyed. Unkey
the transmitter between steps to avoid unnecessary heating.
Note: When aligning transmitter, proceed as instructed below. DO NOT retune a
previously tuned control unless specifically directed to do so.
1 |
B Mult-1 |
T103, T102 & T103 |
See Procedure |
Tune T101 for maximum meter reading. Then tune
T102 for a dip (small) in meter reading and tune T103 for maximum meter reading. |
2 |
C Mult-2 |
T104 and T105 |
See Procedure |
Tune T104 for maximum meter reading, then tune T105 for
a dip (small) in meter reading. |
3 |
D Mult-3 |
T106 and T107 |
See Procedure |
Tune T106 for maximum meter reading, then tune T107 for
a dip in meter reading. |
4 |
F Mult-4 |
T108 and C155 |
See Procedure |
Tune T108 for maximum meter reading, then tune C155 for
a dip in meter reading. |
5 |
G Ampl-1 |
C157 and C 167 |
See Procedure |
Tune C157 for maximum meter reading, then tune C167 for
a dip in meter reading. |
6 |
A Rel Power Out |
C171 and C175 |
Maximum |
Tune C171 and C175 for maximum meter reading. |
7 |
B Mult 1 |
T101 |
Maximum |
Tune T101 for maximum meter reading |
8 |
C Mult-2 |
T102, T103, T104 |
Maximum |
In order, tune T102, T103 and T104 for maximum meter
reading. |
9 |
D Mult 3 |
T105 and T106 |
Maximum |
Tune T105 and then T106 for maximum meter reading. |
10 |
F Mult 4 |
T107 and T108 |
Maximum |
Tune T107 and T108 for maximum meter reading |
11 |
G Ampl 1 |
C155 andC157 |
Maximum |
Tune C155 and then C157 for maximum meter reading |
12 |
A Rel Power Out |
C167, C171 & C175 |
Maximum |
In order, tune C167, C171 and C175 for maximum meter
reading |
|
|
|
|
A quick transmitter tune-up procedure is provided in
steps 13 through 17. |
13 |
C Mult 2 |
T102, T103 and T104 |
Maximum |
Alternately tune T102, T103, T104 for maximum meter
reading. |
14 |
D Mult 3 |
T105 and T106 |
Maximum |
Alternately tune T105 and T106 for maximum meter
reading. |
15 |
F Mult 4 |
T107 and T108 |
Maximum |
Alternately tune T107 and T108 for maximum meter
reading. |
16 |
G Ampl 1 |
C155 andC157 |
Maximum |
Tune C155 and then C157 for maximum meter reading.
For optimum operation repeat steps 13 and 16. |
17 |
A Rel Power Out |
C167, C171 & C175 |
Maximum |
In order, tune C167, C171 and C175 for maximum meter
reading |
|
|
R213 |
|
With the battery voltage at 13.6 Volts or the PA
collector voltage at 13.0 Volts, set Power Adjust potentiometer R213 on the PA board for
the desired power output from 1 to 40 watts. |