Off Center Fed (OCF) Dipole Baluns

1112255371 - Off Center Fed (OCF) Dipole Baluns
+3

MINI-CHOKER Coax Line Isolator, 500 Watts PEP, up to -38Db Common Mode Rejection, 1-61 MHz, 1:1 Unun

MC-1-500-50
$69.95
In stock
1
Product Details
Brand: Palomar Engineers
MPN: MC-1-500-50
Country/Region of Manufacture: United States
Effective Frequency Range (MHz): 1-60
PEP Power Rating (watts): 500 SSB (25% duty cycle), 250 Watts CW/FT8 (50% duty cycle)
Choking Impedance Range (ohms): 500-5000 (1-60 Mhz)
Common Mode Attenuation (db): 20-35db
Estimated Insertion Loss (db): .25 db
Input Connector Type: SO-239 female
Output Connector Connector Type: SO-239 female
Enclosure Size (LxWxH inches): 3" long, 2 in wide, 1.25" high

MINI-CHOKER(TM) Features:

- Uses proprietary Multi-Turn ferrite technology for maximum choking (up to -38 dB common mode noise rejection) and maximum bandwidth

- 500 Watts PEP, 50 ohm SO-239 connectors In/Out, 1-61 MHz (usable to 100 MHz) - AKA 1:1 UNUN

- Works for all coax fed antennas from 1.8-61 MHz (160-6 meters) - excellent for multi-band beams, verticals, dipoles, magnetic loops and highly unbalanced off center fed antennas.

- 2-5 times more common mode noise rejection, wider bandwidth and higher power then competing isolators

- Available standard with SO-239 in/out connectors or optional BNC or N in/out connectors

MINI-CHOKER feed line chokes are used to suppress common mode current carried on the outside of the coax braid which is often responsible for receiver noise and RFI in the receiver/transmitter. These chokes are very useful for suppressing RFI common mode current at the antenna feed point, at 1/2 wavelength intervals along the coax feed line and also at the entrance to the radio station.

This choke is available with a SO-239 input/output and ground/static bleeder stud (optional) for attachment to a ground rod. Use an isolator every 1/2 wavelength for the antenna operating frequency (include velocity factor in calculation). Use the ground lug option for long coax antenna feed lines (over 1/2 wavelength at the operating frequency of any antenna system in the near field of the coax).

For Higher Power needs use our MAXI-CHOKER 3KW version part# MC-1-3000 or 5KW version MC-1-5000.






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Testimonial

Hi Bob,

Radio: Flex-6700 running barefoot -10 to 100 Watts max.
Antenna: MFJ-1216 – 160/80 meter OCFD wire antenna with matching network.
Elevation: Over 60 feet AGL – fully extended.
Installed: Mid November 2013

I operate mainly on the digital modes running less than 50 Watts.  All of the sudden after a few days operating with this antenna, I start to have RFI and my radio was acting up; such as changing bands, SWR changing values, radio failures and turning off. However, when I used my Hy-Gain 18 HT vertical on the same band none of the abnormality occurred.
I contacted MFJ and confirm that what I was noticing was a failure of their “matching network” AKA balun.  They offered no solutions. Then I contacted Palomar Engineers and bought the 1:1 new toroid RF beads.  I called Palomar Engineers and I happened to talked to you directly; regarding the on going issue with the MFJ antenna. I found out that the 1:1 balun was not what I needed (I was miss-informed by MFJ that it was 1:1 matching network.)
You offered to make the required balun 4:1 and the rest is history.

Here are my findings:

  1. No more RFI displayed on the monitors.
  2. Radio not acting up or turning off.
  3. The SWR at 160/80 meter is 1.2:1
  4. No antenna tuner required.  (radio goes to Bypass automatically.)
  5. Worst SWR is on 10 meter with a 2:1 but still usable, with antenna tuner 1.5.
  6. One happy OCFD user!

Thanks to Palomar Engineers design and engineering for solving this issue.

73, Ernest – W4EG