Hi-Band MICOR Exciter Tuning Instructions

VHF Motorola MICOR Exciter Tuning Instructions

By Kevin Custer W3KKC

For
TLD5131
TLD5132
TLD5371
TLD5372
TLD8261
TLD8262
TLD4081
TLD4081

If a MICOR Test Set is not available, a needle type meter may be substituted if the meters basic movement is 50 uA. A Simpson 260 or equivalent is an acceptable substitution.

The "Test Set Selector Switch Position" also refers to the corresponding pin of the metering socket. In other words Meter Position 2 also indicates Meter Socket Pin 2.

Meter Socket Pins 6 and 7 are the ground return for the meter.

This diagram will help you understand the numbering of the Metering Socket. Since it is accessable from either side, ohm out pins 6, and 7 to understand orentation.

Step	Adjust	Meter Plug Location	Test Set Selector Switch Position	Meter Reverse Switch and Ref A-B Switch	Stage and Procedure
1					SET-UP - Connect the test equipment and set switches as shown. Key the transmitter with the XMTR ON button on the test set or microphone.
2	Power Set	EXCITER			OUTPUT - Turn POWER SET control fully counterclockwise.
3	Frequency Switch	EXCITER	2	Off REF A	Channel Element - Select the desired frequency on multi-frequency radio sets. Key the transmitter. The test set meter 2 should indicate at least 10 uA.
4	All Exciter Coils	EXCITER	3	Off REF A	Pre-Alignment - If the exciter is completely untuned and shows no meter 3 readings, set cores of all tuning coils to the top of their coil forms (away from the circuit board) and proceed with step 5. If the exciter shows meter 3 readings set cores of all tuning coils except L401 and L402 to the top of their coil forms (away from the circuit board). Tune L401 and L402 in that order for maximum meter indication. Go to step 7 of the procedure.
5	L401	EXCITER	2	Off REF A	Modulator Output - Tune L401 for minimum meter reading.
6	L401 L402	EXCITER	3	Off REF A	Modulator Output - Tune L402, then L401 for peak meter reading.
7	L403	EXCITER	3	Off REF A	Tripler Output - Tune L403 for minimum meter reading.
8	L403 L404	EXCITER	4	Off REF A	Tripler Output - Tune L404 and then L403 for peak meter reading.
9	L405	EXCITER	4	Off REF A	First Doubler Output - Tune L405 for minimum meter reading.
10	L405 L406	EXCITER	5	Off REF A	First Doubler Output - Tune L406 and then L405 for peak meter reading.
11	L407	EXCITER	5	Off REF A	Exciter Output - Tune L407 for minimum meter reading.
12	L407 L408	PA	1	Meter Reverse REF A	Exciter Output - Move the metering plug to the PA. Tune L408 and L407 for peak meter reading.
13					Repeat steps 6, 8, and 10.
14					Align the Power Amplifier.

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