HANDHELD ANTENNA TRIMMING CHARTS

"Rubber Duck" antennas supplied by IRC are not of the broad band type. Tests have shown that radiation levels of broad band "rubber duck" antennas are not optimal. Due to the narrow band characteristics of the antennas supplied by IRC, it is essential that they are  trimmed to match the most used transmit frequency of the radio. 

Length should be measured from the base of the antenna connector (the lowest point of the antenna once mounted on the radio) to the tip of the antenna (excluding the cap)

THESE CHARTS APPLY ONLY TO ANTENNA'S SUPPLIED BY IRC.  IF ANOTHER ANTENNA IS USED, PLEASE CONSULT THE ANTENNA SUPPLIER FOR TRIMMING DETAILS

MIDBAND (Note : Add 5mm for RHM series Hand Held Radio)

FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH
	mm		mm		mm		mm		mm		mm
66	210	70	195	74	182	78	169	82	160	86	151
67	205	71	191	75	180	79	167	83	158	87	149
68	201	72	189	76	177	80	165	84	156	88	147
69	197	73	185	77	173	81	162	85	153

VHF (Note : Add 5mm for RHM series Hand Held Radio)

FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH	FREQ	LENGTH
	mm		mm		mm		mm		mm		mm
135	182	142	175	149	165	156	157	163	150	170	146
136	181	143	174	150	164	157	156	164	149	171	146
137	180	144	173	151	163	158	155	165	149	172	145
138	179	145	171	152	162	159	154	166	148	173	145
139	178	146	170	153	160	160	154	167	148	174	144
140	177	147	168	154	159	161	152	168	147	175	144
141	176	148	167	155	158	162	151	169	147

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