Off Center Fed (OCF) Dipole Baluns

2465476302 - Off Center Fed (OCF) Dipole Baluns
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Elecraft KPA500 HF Linear Amplifier RFI Kit - 5 Filters for RF In/Out, AC Power, PA KEY, Computer Control/AUX/RS232

RFI-ELECRAFT-KPA500
$49.95
In stock
1
Product Details
MPN: RFI-ELECRAFT-KPA500
Type: New
Country/Region of Manufacture: United States
Filter Power Rating (PEP watts): coax cable limit
RFI Suppression Range (MHz): 1-300 MHz
# Ferrite Filters: 5
Typical Use:: AC power, RF In/out, I/O control cables

This is a generic linear amplifier RFI kit for DC powered amplifiers. Works on many popular amplifiers including:

Specially designed for the Elecraft KPA500 linear amplifier used with the KX3 and similar transceivers.

Included are the following chokes and installation guidelines:

Included are the following chokes and installation guidelines:

RF Input:F240 ring – 5-9 turns of RG-58 size through center

RF Output:FSB-1 (Big Clamp on) – 3 turns of RG-8 size cable

PA KEY Cable:FSB-1/2 – multiple turns through choke – ½” diameter hole

AC Power Line:F240 ring – 5-6 turns through center

Computer/RS232/AUX Cable:FSB-1/2 – multiple turns through choke – ½” diameter hole

Also make sure you connect a good RF ground to the amplifier ground post.

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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