RF SYTEMS hf antenna

[hfdxer]

Is anybody using this antenna for hf????

The RF Systems DX-One Professional MkII is an omni directional active vertical receiving antenna covering 20 kHz to 60 MHz (10 kHz to 90 MHz with reduced specs). The multi-polarized DX-One Pro MkII addresses the issue of polarization fading found so often on shortwave. Another outstanding feature of the DX-One Pro is its excellent resistance to intermodulation problems. The rear panel has two isolated SO-239 outputs for two receivers. The user must supply coax between the antenna and the control box (PL-259 to PL-259). The control box unit features a step attenuator (+6 dB to -40 dB). It also has a switchable medium wave suppression feature which suppress signals from 540-1640 kHz by up to 40 dB.

 

[ka3jjz]

Nice to be able to spend that kind of money - damn, that's one expensive antenna.

If it were me and I had the space, I would run (not walk) to getting a PAR EF-SWL. Much less cost. If I had more than 45 foot of space, I'd replace the wire run with something longer. In some cases, at least, it would outperform your Alpha Delta sloper on the frequencies that it is NOT designed to cover. It would make a nice 2nd antenna, for sure. In fact, it might be an interesting experiment to mount the PAR as a sloper and make a side by side comparison. You would have to keep it very far apart though to avoid interaction between the 2 antennas.

73 Mike

[edit] Below is the link (which is really all that's necessary - no need to quote it verbatim) from Universal Radio. If you have a bad heart or are prone to strokes, do NOT look at the price. You have been warned...

http://www.universal-radio.com/catalog/sw_ant/1246.html

 

[hfdxer]

I have seen this antenna on top of government and many embassies. obviously it does not look like its cheap. must be a good antenna. The alpha delta dx ultra does a wonderful job at my qth. Probably only beaten by really expensive commercial rhombics, penants, etc. Wellbrook loop is probably a good contester. Par End not too sure about that one.

 

[RadioDaze]

Raving Mini-Review of the EF-SWL

If it were me and I had the space, I would run (not walk) to getting a PAR EF-SWL. Much less cost. If I had more than 45 foot of space, I'd replace the wire run with something longer.

I just got my EF-SWL a couple of days ago. Showed promising results semi-unfurled in the house.

Well, not actually a house. A 3rd floor condo, in a very restrictive community. Turns out, I really don't have nearly the full 45 ft. to stretch it out. Certainly not outside. I have a small balcony, and I would have to fold the wire several times.

So I had a thought, and I took off its very durable 45' wire, and ran a 16 gauge wire from the EF-SWL to an approximately 25 foot rain gutter that makes a straight run straight along my eave. It would have an unimpeded lobe pointing southwest over the blue Pacific, and pretty well blocked toward the northeast. EF-SWL is grounded to a cold water pipe.

My noise floor used to run 7 to 9, using a plain random wire, inside the house. With the EF-SWL I got it as low as 1 with some combination of grounding and the 45 foot wire scattered around inside, but with marginal reception that was at least easier on the ears if nothing else. Now, with the rain gutter, I have a noise floor of 1, with MANY, MANY ham stations at 80 meters coming in. And many SW broadcast stations coming in loud and clear.

I just literally finished setting this up and testing it about 20 minutes ago, so I don't have any detailed reports yet. I had to work in the dark of night so nobody would get suspicious. But this PAR antenna is working great in it's unusual configuration. I can quickly disconnect it from its current location and put the 45 footer back on if I want to travel with it.

 

[Turbo68]

Hi i use to have the Rf Sytems Dx-One Professional MkII the performance on hf was excellent mainly monitor aero/marine bought the Wellbrook-Ala1530 Active Loop and the perfromance is as good on hf i did a test a few weeks ago at my dads place stayed up late night to compare both antennas with excellent result on both noise floor of 1 radios we used where Aor-7030, Icom-R75,Icom-R9500,Nrd-545,Palstar-R30A,Ten Tec-Rx
340.

Regards Lino.

 

[prcguy]

The DX-One has some of the most impressive specs I've seen for a commercially made active VLF/HF antenna, a third order intercept of 52dBM is quite impressive and would be immune from most intermod problems.

However, you can build an antenna that will probably outperform it for about $75 with a 3rd order intercept of 53dBM and a little more gain. Check out the AMRAD active antenna:
http://www.arrl.org/tis/info/pdf/0109031.pdf

These are a semi kit where you get the circuit boards and then hunt for the parts and build the enclosure. The heart of the antenna is a special monster FET and it also has two independent outputs.

I built one and its a really nice antenna. It brings in some things like VLF beacons better than my G5RV at 30ft and is very quiet for an active antenna. There is a supplement to the original article that has an updated parts list and a Google search should find this.
prcguy

 

[zz0468]

I just read the article, and I'm tempted to build one. Current price for the CP666 jfet? $17.50! $25 in the surface mount version.