Off Center Fed (OCF) Dipole Baluns

FT240-3I, ID=1.4", AC/DC/Coax Noise Filter, RFI Range 1-300 MHz, Case of 100

F240-31-100
$795.00
In stock
1
Product Details
MPN: F240-31
Country/Region of Manufacture: China
RFI Range (MHz): 1-300 Mhz
ID-B (in/mm): 1.4/35.6
OD-A (in/mm): 2.4/61
Height-C (in/mm): .5/12.7
Weight (oz/gm): 188 grams
Initial permeability: 1500
Case/Box lot size: 100
: 100
: 7.50

Case of 100 ferrite ring cores - Very useful for AC/DC power, coax cable common mode current suppression. For highest choking resistance, wrap cable through center of ring as many turns as possible. DO NOT use for impedance transformers (2:1, 4:1, 9:1, etc.) - use Mix 43 or Mix 61 for high power.

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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