Off Center Fed (OCF) Dipole Baluns

1072922501 - Off Center Fed (OCF) Dipole Baluns
+3

50:450 ohm (9:1) Balun or Unun Core Kit, .5-32 MHz, 1000 watts PEP, end fed/Ladder Line, T2FD antenna

BA-9-1000
$29.95
In stock
1
Product Details
MPN: BA-9-1000
Type: balun or unun
Input ohms/Output ohms: 50 in, 450 out
Frequency Range < 2:1 SWR (MHz): .5-32
PEP Power Rating (watts): 1000 Watts PEP
Antenna Compatability: Unun: End fed, Balun: Ladder line

Purpose. Model BA-9-1000 is a 9:1 balun/unun kit (assembly required from parts supplied) used to translate a 50 ohm input up to 450 ohms at RF power levels up to 1000 watts when used with a matched load. It provides conversion from unbalanced coax to balanced ladder line/antenna feed point and gives a 9:1 impedance step-up to reduce SWR on the coax. Place at the junction of the balanced line and the coax to convert from balanced line to unbalanced coax.It can also be wired as an UNUN with unbalanced coax input to unbalanced output such as an end fed antenna.

KIT Contents. The kit consists of a F240-61 ferrite toroidal core, three colors of insulated wire, a SO-239 UHF connector with stainless steel hardware, and an instruction manual.

Assembly time: About 1 hour

Radio Club idea:

Buy 10 for a club do it yourself construction project - you can learn something and also build an end fed antenna (just add wire).

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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