OCF Dipole - Palomar Engineering

[N1NTE]

Researching OCF dipoles I found the following...

Palomar Engineering's PAL-OCF8010:

http://palomar-engineers.com/tech-support/tech-topics/off-center-fed-ocf-antennas

This antenna seems to be reasonably priced. It also doesn't use a voltage balun for 15 meter coverage by using the coax as a radiator. A "resonance compensator" is used instead for 15 meters on the long side which I assume is a trap.

Does anyone have any experience with this model or other recommendations?

- Rob

[W3GMS]

Rob,

A local Ham to me just bought the version from Buckmaster and he is very pleased with it.  Saying that, its his first antenna so he does not really have anything to compare it to.  He works many stations and is happy! 

Here is a good article on this type of antenna:

http://www.w8ji.com/windom_off_center_fed.htm

Joe-W3GMS

[N2DTS]

Another good option at that power level is the Alpha Delta LB antenna's.
I had the LB plus, 160 to 10 in about 130 feet.
It worked very well above 160 and the RX on 160 was great, TX would likely have been poor.

It uses coils not traps, and if you run no more then 100 watts carrier it is ok.
At higher power levels the coils heat up and can melt and deform, not a problem on ssb or CW, or AM below about 150 watts carrier.
Without the 160 part the length is even less.

[N1NTE]

Update:

Purchased and installed the Palomar Engineers OCF dipole last weekend. It is at about 80 feet up in the clear. Sweeped the MFJ analyzer across the range and it was almost identical to the curves posted on their website. The top end of 75m is a little high but very useable.

Running some real world tests now but looks to be what is advertised. A low profile very satisfactory alternative to a "fan" type multiband dipole.

- Rob

[WD5JKO]

  Rob,

   I would like to hear any further updates once you get some time on this new antenna. I bet that the SWR curves would be skewed substantially if you installed this as an inverted V, or as a dipole at 30'.

   That reminds me, remember those W9INN antenna adds that were in the back of QST? The guy would tune his antennas after configuring the installation to match the end users layout. I think he became a SK about 10 years ago.

Jim
Wd5JKO

[N1NTE]

I would like to hear any further updates once you get some time on this new antenna. I bet that the SWR curves would be skewed substantially if you installed this as an inverted V, or as a dipole at 30'.

The curves on their website are for an antenna at 30 ft. I talked with one of their engineers about the impedance change at 80 feet and he felt it wouldn't be an issue which proved out with the MFJ. I was surprised to see it follow their curves so accurately.

As for inverted V, the website says "Angle of feed each side must be great than 45 degrees or 120 – 180 degrees total between each side preferred." So it looks like the V would need to be more on the wide side.

SWR is very high on 160m (expected) but it receives really well. So far, I am very please with it and will report back when I get some transmit stories to tell.

- Rob

[N2DTS]

I would not expect to be able to run very much power on AM.
Maybe 100 watts if the swr is not very high.

Any kind of balun or trap will not hold up if there is any swr and sometimes even with none those things fry.

I have never had anything hold up to any power except wire and coax.

[N1NTE]

Not running high power here. Installation at this location was not open line feeder friendly (feed had to be buried to the building) so coax was the only option. Otherwise I would have probably gone with a open wire multiband dipole and a tuner.

- Rob

[N2DTS]

My setup, coax fed.



Only 80 and 40 but no tuna, under 1.5 to 1 swr and no power limitations or things with loss in them.

I may take down the other 40 meter dipole and put a a 40 to 10 fan.

https://n2dts.smugmug.com/Ham-radio/i-Mm462d2/A

[W4EWH]

My setup, coax fed.

OM, you have the magic touch: I tried an OCF  set up almost exactly like yours.

My wife could hear me on every phone in the house.

Bill, KW4OC

[N2DTS]

Mine is center fed, I do trip the ground fault in the kitchen if I use the antenna that is right over the kitchen at high power.