The C31XR-JK (Tribander) has been re-designed, optimized & Improved from the very popular Force 12 Tribander of all times for contesters and Dx’ers.

3 Elements on 20M / 4 Elements on 15M / 6 Elements on 10M / 30 Foot

Here are the important changes/features from the classic design ….

1. The Boom has been shortened by a foot to make it a 30Ft boom yagi

2. The feed point for 20M, 15M & 10M are connected using a transmission line, the same way as the JK-MidTri & JK-BigTri.

3. The mast mount position is right at the center of the antenna at 180″ with a gap of 25″ on either side for a total gap of 50″, which enables unhindered mounting on ring-rotors or side-mounting on towers.

4. The total number of elements on 10M has been reduced by 1 (one) element while optimizing gain and swr.

5. The overall gain and swr on all bands is consistent & provides excellent performance. (click here)

Price : US$1,895.00 **

Approx wt. = 110 lbs

Wind Area = 12.4 Sq. Ft

Max Wind Speed = 100 Mph

Max Turning Radius = 24 Ft

Feedpoint = Direct 50-Ohm

Peak Gain is shown over a dipole in Freespace
Dipole in Freespace = 2.14dBi

FREESPACE PLOTS – Single Antenna

	10M	15M	20M
Number Elements	6	4	3
Active Boom Length	24 ft	24.5 ft	26.5 ft
Peak Gain*	8+ dBd/10+ dbi	7.5 dBd/ 9.5+ dbi	6 dBd/ 8.2+ dbi
Peak F/B	20+ dB	15 dB	18 dB
Peak F/R	20+ dB	15 dB	18 dB
2:1 SWR Bandwidth	850 KHz	Less than 1.6:1 across the band	Less than 1.5:1 across the band
1.5:1 SWR Bandwidth	650 KHz	450 KHz	350 KHz
Max Element Length	18 ft	24.25 ft	36.5 ft

C31XR-JK : NEC4 – Freespace Gain, SWR & F/B values

Freq	R	X	SWR	Gain	Azimuth Angle	F/B	F/R
14.000	55.38	-23.00	1.561	8.22	0	16.86	16.86
14.025	53.35	-20.02	1.478	8.23	0	17.34	17.34
14.050	51.44	-17.17	1.402	8.24	0	17.75	17.75
14.075	49.63	-14.45	1.335	8.25	0	18.07	18.07
14.100	47.92	-11.84	1.278	8.26	0	18.29	18.29
14.125	46.28	-9.33	1.232	8.27	0	18.40	18.40
14.150	44.73	-6.91	1.202	8.28	0	18.40	18.40
14.175	43.24	-4.58	1.192	8.29	0	18.29	18.29
14.200	41.81	-2.33	1.204	8.30	0	18.08	18.08
14.225	40.45	-0.15	1.236	8.31	0	17.81	17.81
14.250	39.13	1.97	1.283	8.32	0	17.47	17.47
14.275	37.87	4.03	1.340	8.33	0	17.09	17.09
14.300	36.65	6.04	1.406	8.35	0	16.69	16.69
14.325	35.48	8.00	1.479	8.36	0	16.26	16.26
14.350	34.35	9.91	1.558	8.37	0	15.83	15.83

Freq	R	X	SWR	Gain	Azimuth Angle	F/B	F/R
21.000	52.94	-25.35	1.634	9.50	0	15.66	15.66
21.025	54.09	-19.77	1.471	9.53	0	15.62	15.62
21.050	55.30	-14.68	1.344	9.55	0	15.58	15.58
21.075	56.53	-10.09	1.253	9.58	0	15.54	15.54
21.100	57.77	-6.01	1.200	9.60	0	15.49	15.49
21.125	58.96	-2.46	1.186	9.62	0	15.44	15.44
21.150	60.06	0.55	1.202	9.65	0	15.40	15.40
21.175	61.00	3.02	1.229	9.67	0	15.36	15.36
21.200	61.68	4.96	1.256	9.69	0	15.31	15.31
21.225	62.01	6.38	1.276	9.71	0	15.26	15.26
21.250	61.87	7.35	1.285	9.73	0	15.21	15.21
21.275	61.16	7.96	1.280	9.75	0	15.14	15.14
21.300	59.77	8.35	1.264	9.77	0	15.05	15.05
21.325	57.65	8.70	1.240	9.79	0	14.94	14.94
21.350	54.79	9.20	1.219	9.81	0	14.79	14.79
21.375	51.27	10.05	1.221	9.83	0	14.59	14.59
21.400	47.21	11.44	1.273	9.85	0	14.34	14.34
21.425	42.78	13.48	1.390	9.87	0	14.03	14.03
21.450	38.20	16.22	1.576	9.89	0	13.64	13.64

Freq	R	X	SWR	Gain	Azimuth Angle	F/B	F/R
28.000	44.58	-5.84	1.184	10.01	0	16.08	16.08
28.050	46.90	-3.48	1.101	10.05	0	16.50	16.50
28.100	49.15	-1.60	1.037	10.09	0	16.98	16.98
28.150	51.21	-0.22	1.025	10.13	0	17.52	17.52
28.200	52.95	0.70	1.061	10.17	0	18.17	18.17
28.250	54.22	1.24	1.088	10.23	0	18.95	18.95
28.300	54.93	1.56	1.104	10.28	0	19.88	19.88
28.350	55.07	1.86	1.108	10.33	0	21.01	21.01
28.400	54.69	2.31	1.105	10.38	0	22.31	22.31
28.450	53.97	3.05	1.101	10.42	0	23.64	23.64
28.500	53.13	4.12	1.106	10.44	0	24.51	24.51
28.550	52.44	5.40	1.123	10.46	0	24.22	24.22
28.600	52.11	6.56	1.145	10.46	0	22.73	22.73
28.650	52.19	7.01	1.155	10.43	0	20.76	20.76
28.700	52.17	5.88	1.130	10.37	0	18.86	18.86
28.750	50.46	2.44	1.051	10.28	0	17.25	17.25
28.800	44.21	-2.10	1.140	10.12	0	15.96	15.96

Review

TYT MD-2017 Dual Band DMR Digital Radio Unboxing

June 07, 2017 in: Review No comments

TYT MD-2017 Features 3000 Channels 400-480MHz UHF Frequencies 136-174MHz VHF Frequencies Built-in CTCSS/DCS (Analog Mode) 5W/1W Output Power Repeater Capable Uses Li-ion Rechargeable Battery Packs Rechargeable Li-ion Battery Pack Included I... Read more

Bridgecom Systems REVEALS the Skybridge Hotspot | EASY Pi-star Setup

September 22, 2020 No comments
Coax Cable Loss – Ham Radio Basics

September 12, 2016 No comments
Icom 7610 HDSDR CW Skimmer Narrow

September 20, 2018 No comments
Xiegu XPA125B Ham Radio Amplifier

July 10, 2020 No comments

VHF

FTM-6000E Dual-Band FM Mobile Transceiver – Hands-on Demo!

November 12, 2021 in: VHF No comments

The FTM-6000E delivers reliable and stable 50W transmit performance. The heavy-duty heat sink is equipped with FACC (Funnel Air-Convection Conductor). The speaker delivers 3W of clear and crisp receive audio which has been specifically tune... Read more